Resumo em Inglês:

ABSTRACT With the increasing demand for sustainable building materials, researchers have developed geopolymer-based tiles using bauxite residue (BR) and other industrial by-products. This approach supports the zero-waste concept by converting waste from alumina refineries, steel plants, and coal-fired power stations into value-added products. The primary constituents include BR, ground granulated blast furnace slag (GGBS), and fly ash (FA), while manufactured sand (MS) and quarry chips (QC) were used as fillers. A small I-Crete (IC) dosage was incorporated as an admixture to improve overall performance. BR exhibits moderate reactivity compared to conventional binders, and its influence was studied at different replacement levels. The optimum mix was 30% BR, 20% GGBS, and 50% FA, with a filler-to-binder ratio of 1:1.5 and 2% I-Crete (R30G20F50I02). Sodium silicate and sodium hydroxide with 4M concentration were alkaline activators. After 28 days of curing, the developed tiles showed excellent flatness (0.6 mm), perpendicularity (<1%), straightness (<0.8%), wet transverse strength of 6.285 N/mm2, wear resistance of 3.26 mm, and water absorption of 5.59%. All properties satisfied IS 13801-2013 standards, making the tiles suitable for outdoor flooring such as walkways, patios, warehouses, and factory surfaces.

Resumo em Inglês:

ABSTRACT Conventional calcium bentonite suffers from poor rheological properties and poor static stability.To address these challenges, this study developed a novel sodium-activated bentonite composite modified with natural citrus pectin (CP) through chemical intercalation, termed Na-BT-CP. Under optimized conditions (0.8 wt% CP), the composite demonstrated a synergistic enhancement in rheological properties at 80°C, with a 44% increase in apparent viscosity and a remarkable 175% surge in the yield point-to-plastic viscosity ratio (YP/PV). The material exhibited exceptional thermal stability, maintaining viscosity fluctuations below 1.3% within the 25–100°C range, and outstanding static stability with less than 2.6% performance attenuation after 24 hours. XRD and FT-IR analyses confirmed the successful intercalation of CP into the bentonite interlayers, forming a synergistic bonding network via Na+ bridging and hydrogen bonding. This work provides a new pathway for developing high-performance, environmentally friendly drilling fluid materials using renewable resources.

Resumo em Inglês:

ABSTRACT This study evaluates the fracture behavior of concrete produced with recycled coarse aggregate and reinforced with 1% by volume of fibers PET. The experimental program included three-point bending tests on notched beams, following the RILEM recommendations for determining fracture energy, critical stress intensity factor KIC, and critical crack tip opening displacement (CTODC). The adopted methodology allows a detailed analysis of the material response under cyclic loading. The results indicated a 36.67% increase in fractured energy, rising from 95.05 N/m in reference concrete to 129.91 N/m in fiber-reinforced concrete. In addition, KIC increased from 1.38 to 1.59 MPa · m1/2, corresponding to a 15.22% gain, while CTODC rose from 0.0055 to 0.0079 mm, equivalent to 43.64%. Although the reference beams exhibited higher peak load, fiber incorporation improved the post-cracking behavior, with greater energy dissipation and more controlled crack propagation. These findings show that recycled PET fibers enhance concrete toughness and ductility, even with recycled coarse aggregates. Practically, this improvement in post-cracking performance suggests longer service life and greater safety for structural elements. Thus, the proposed mixture is a technically viable and environmentally sustainable alternative for structural applications using recycled materials.

Resumo em Inglês:

ABSTRACT Advancements in the fundamental healthcare technology known as Wireless Body Area Networks transform wearables into a medium to monitor healthcare in real time. Advanced materials become essential for sensor fabrication within body-deployed systems that need to collect precise data and maintain low power requirements and extended lifecycles. Security issues persist in integrating these sensors into secure communication networks when health data needs protection. This paper investigates sensor materials used in WBANs, emphasizing their performance aspects such as energy efficiency, data protection, and security measures. A new security framework adopts both Merkle-Hellman encryption and transmission techniques that use compression to defend WBANs data transmission. Our approach brings together advanced sensor materials and lightweight encryption algorithms to improve WBAN reliability while ensuring security at an optimal performance level. This research presents a new way to enhance the security and performance of Wireless Body Area Networks (WBANs) by using improved sensor materials along with Merkle-Hellman encryption and compression methods. This new framework enhances energy economy, data security, and net-work resilience, making it a promising choice for future healthcare applications. Experimental tests prove that combining such materials with cryptographic methods enhances network efficiency and data security and energy management to offer a promising solution for healthcare applications of the future.

Resumo em Inglês:

ABSTRACT Natural fibers are gaining significant research attention due to their ecological, renewable, and environmentally friendly nature, making them attractive alternatives to synthetic reinforcements. This experimental study investigates the thermo-mechanical behavior of Peepal fiber (PF) reinforced epoxy composites modified with Ziziphus mauritiana seed powder (ZMSP). Hybrid composites were fabricated by maintaining a fixed fiber weight fraction of 40% PF, while varying the particle content at 3, 6, 9, and 12 wt%. Prior to incorporation, the particles were chemically treated with 5% NaOH and characterized using FTIR, XRD, and TGA analyses. The treatment increased crystallinity index, enhanced thermal stability, and promoted better interfacial adhesion with the matrix. Mechanical tests revealed that composites with 3 wt% filler displayed the highest impact strength, whereas 9 wt% filler exhibited optimum tensile, compressive, flexural, hardness, and fracture toughness properties. Thermogravimetric analysis confirmed enhanced thermal resistance, while water absorption and biodegradability increased with particle loading. SEM micrographs illustrated improved fiber–matrix interaction and reduced void formation at optimal filler content. The combined improvements in strength, toughness, and stability demonstrate that PF–ZMSP hybrid composites can serve as sustainable, cost-effective, and lightweight materials suitable for moderate load-bearing applications in automotive, structural, and industrial sectors.

Resumo em Inglês:

ABSTRACT In cold regions, hot recycled asphalt mixtures often suffer from low-temperature cracking. Basalt fiber, a widely recognized toughening material, offers promising potential to mitigate this issue. This study employs digital image correlation to monitor the fracture evolution during semi-circular bending tests, focusing on the reinforcing effect of basalt fibers and analyzing their contribution to improving the low-temperature fracture resistance of RHMA under different RAP contents. Fracture energy, fracture toughness, and crack tortuosity were utilized as key indicators of crack resistance. The correlations between crack tortuosity and both fracture energy and fracture toughness were analyzed, while strain fields and horizontal displacements at observation points were analyzed to characterize the cracking process. The results demonstrate that the incorporation of basalt fibers enhances fracture energy by 23%–39% and improves fracture toughness by 10%–21%. Moreover, basalt fibers significantly altered the crack propagation path, increasing crack tortuosity by 8.2%–12.8%. An increase in RAP content intensified the stress concentration on both sides of the crack, leading to pronounced local strain accumulation at the crack tip. The presence of basalt fibers effectively reduced strain concentration near the crack tip, dispersed high-strain zones, and delayed crack propagation, thereby enhancing the overall fracture resistance of the mixture.

Resumo em Inglês:

ABSTRACT This study explores the use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for the direct quantification of cadmium in human hair, addressing the demand for rapid, spatially resolved, and minimally destructive biomonitoring methods. Cadmium, a toxic heavy metal associated with renal and metabolic disorders, is typically measured using techniques that require extensive sample preparation, potentially compromising temporal and spatial exposure data. This work fills the gap in validated LA-ICP-MS hair analysis protocols by implementing matrix-matched calibration and validating the method against solution nebulization ICP-MS. The aim was to develop a robust, high-resolution technique capable of accurately quantifying cadmium across a broad concentration range. Calibration curves were prepared using certified reference materials, and method performance was evaluated through precision, accuracy, reproducibility, and depth-profile analysis. The method showed excellent linearity (R2 > 0.999), with cadmium levels in environmentally exposed individuals exceeding EPA thresholds by up to 1100%, indicating elevated renal toxicity risk. Spatial mapping revealed distinct cadmium peaks linked to occupational and environmental exposure events, while zinc and sulfur served as stable internal standards, enhancing reliability. These results position LA-ICP-MS as a powerful alternative to conventional methods, with future work focusing on population studies, and isotopic tracing for source attribution.

Resumo em Inglês:

ABSTRACT This study aims to evaluate the potential of date palm seed (DPS) particles—an abundant agro-waste byproduct—as a sustainable filler for enhancing the performance of epoxy-based composites. Epoxy composites were fabricated with DPS loadings ranging from 10 to 50 vol%, and their mechanical (compressive strength, impact resistance, hardness), thermal (conductivity), and chemical (FTIR spectroscopy) properties were systematically investigated. The results demonstrated that a DPS content of 30 vol% yielded optimal mechanical performance, with compressive strength reaching approximately 64.5 MPa, alongside notable increases in hardness and impact resistance. Conversely, thermal conductivity decreased progressively with filler content, attaining a minimum of 0.136 W/m·°C at 50 vol% DPS. FTIR analysis confirmed the presence of physical interactions—particularly hydrogen bonding—between the epoxy matrix and DPS particles, while spectra post-impact suggested structural stability with minimal chemical degradation. These findings indicate that DPS is a promising eco-friendly reinforcement for multifunctional epoxy composites, offering improved mechanical resilience and enhanced thermal insulation.

Resumo em Inglês:

ABSTRACT Ecological river slope protection techniques have received considerable attention for sustainable development. This study focuses on a newly developed material called cast-in-situ vegetation concrete (CVC), which incorporates vegetation and punched holes. A series of anti-scouring tests were conducted to optimize its construction parameters. Wave scouring tests on bare slopes and rainfall scouring tests on vegetated slopes were carried out to evaluate the effects of flow velocity, rainfall intensity, slope gradient, punched hole parameters, and construction thickness on underlying soil erosion. Additionally, high-flow scouring tests were conducted to examine the overall survival status of vegetation after scouring under different construction thicknesses and perforation parameters. The results indicate that flow velocity, rainfall intensity, and slope gradient are positively correlated with soil erosion. Among these, Perforation Group A (4.5 cm in depth, 2.5 cm in diameter, 2.8 cm in spacing) demonstrated superior performance to Perforation Group B (4.0 cm in depth, 1.0 cm in diameter, 3.5 cm in spacing), exhibiting lower erosion volume and better vegetation-reinforced slope protection effects. In terms of promoting stable vegetation survival, construction thicknesses of 6 cm or 10 cm were found to be preferable to 15 cm. Therefore, the parameters of Perforation Group A with a thickness of 6 cm or 10 cm are recommended. These findings offer practical guidance for the application of Cast-in-place Vegetation Concrete (CVC) technology in ecological slope protection.

Resumo em Inglês:

ABSTRACT Increasing the demand for efficient energy usage in buildings has urged the use of Building Information Modeling (BIM)-oriented simulation methods to streamline energy optimization. Conventional assessment approaches suffer from low accuracy caused by static nature and less capability of predictive estimations. The present work intends to propose an enhanced BIM-based energy performance simulation process supported by ensemble learning for boosting predictability toward effective retrofitting of aging buildings to be more sustainable. Creating a successful predictive model that combines numerous machine learning methods is the primary objective of this study to enhance the accuracy of energy consumption forecasting. The approach employs a hybrid ensemble model that improves prediction accuracy by fusing Extreme Gradient Boosting (XGBoost) and Random Forest (RF). The BDG2 dataset with hourly energy consumption records and metadata of different building types is employed for model testing and training. Python machine learning libraries like Scikit-Learn and XGBoost are used in deployment. Leveraging the respective strengths of the two models, the introduced ensemble approach is capable of well identifying nonlinear patterns in energy use, reducing overfitting, and enhancing generalizability for different building types. Experimental outcomes show that the developed ensemble model performs 94.1% accuracy, 93.5% precision, 92.8% recall, and 93.1% F1-score. Results show an outstanding improvement over standalone models with consistent predictions for enhanced building energy efficiency. Results confirm the success of combining BIM with machine learning-based energy performance analysis as a scalable effective means of sustainable retrofitting.

Resumo em Inglês:

ABSTRACT Currently, it is crucial to develop innovative materials for treating various diseases. Thus, this research produces innovative hydrogels incorporating a natural extract from Morinda citrifolia leaves from the semiarid region of Brazil, demonstrating antibacterial and antifungal activity. These hydrogels were characterized by spectroscopic analysis (Raman, UV–VIS), Zeta potential, and Dynamic Light Scattering (DLS). Additionally, the kinetic release of the extract was performed. Moreover, antibacterial and antifungal activities were performed against Escherichia coli and Candida albicans, respectively. The results showed that nanoencapsulation of the colloidal extract modified the physicochemical properties of the hydrogels. In addition, the nano-encapsulation was homogeneously dispersed within the hydrogel. Moreover, the kinetic release of the natural extract demonstrated effective release kinetics due to the different molecules released over time. Furthermore, the antibacterial and antifungal activity showed great results after 24 hours. These results confirm the potential of using these hydrogels as therapeutic biomaterials for “Antibiotic-free” and “Antifungal-free’ health problems.

Resumo em Inglês:

ABSTRACT This research aims to explore the mechanical and durability properties of geopolymer concrete (GPC) with varying content of fly ash, Ground Granulated Blast Furnace Slag (GGBS), biochar, and nano-cellulose fibres under different curing conditions. GPC, compared to traditional concrete, showed superior strength properties, particularly in mixture containing optimized GGBS and biochar. The maximum 28 day compressive strength of 61.12 MPa was recorded in the mixture containing 22% fly ash, 72% GGBS, 6% biochar, and 0.6% nano-cellulose fibres. The mixture also exhibited good workability and enhanced tensile and flexural strengths. Tests of durability such as Rapid Chloride Permeability Test (RCPT), acid and sulphate resistance, and carbonation depth indicated that additions of biochar and nano-fibres greatly alleviated permeability and strength loss. Nano-cellulose fibres have also improved matrix compaction, minimizing carbonation depth and enhancing durability in aggressive exposures. ANOVA has ensured that there were significant workability and compressive strength differences, whereas RCPT differences were statistically insignificant, indicating time-dependent variability in chloride resistance. In general, the incorporation of biochar and nano-cellulose fibres into GGBS rich GPC enhances mechanical strength and durability, justifying its viability as a green replacement for ordinary Portland cement (OPC) for long-term infrastructure construction under extreme environmental conditions.

Resumo em Inglês:

ABSTRACT This study investigates the limitations of biomineralization for the surface treatment of cracks in cement pastes. The proposed strategy involves the application of Pythium aphanidermatum spores on pre-carbonated cement matrices with induced cracks. The pastes were reinforced with polypropylene fibers, cracked via diametral compression, and subsequently subjected to a controlled carbonation process. Three treatment conditions were evaluated: water (Ref) and two biological solutions (T1 and T2) containing calcium acetate, Potato Dextrose Broth (PDB), and Pythium spores; T2 also included urea as an additional nutrient source. Treatment performance was assessed through load recovery and crack width closure. Additionally, SEM analysis was performed to detect microbial colonization along crack surfaces. The results showed limited mechanical improvement, with slightly better performance in T1 and T2. However, no measurable crack width healing (CWH ≈ 0%) was detected, and no microbial growth was observed, likely due to high alkalinity, low surface porosity, and poor nutrient retention in the treated zone. Despite the modest outcomes, the study introduces an innovative approach that combines accelerated carbonation and surface biomineralization using a non-bacterial microorganism. For future studies, it is recommended to investigate multiple treatment applications, encapsulation systems for spore delivery, surface modification to enhance microbial adhesion, and local pH monitoring to ensure optimal conditions for microbial growth and activity.

Resumo em Inglês:

ABSTRACT The validation stage is fundamental for implementation process of any project. Regarding the validation of automotive headlamps and rearlamps, most components must be obtained by thermoplastic injection, which becomes costly due to the necessity of acquire the tooling, requiring time and high costs to adjust the manufacturing injection molds. In the pursuit of maximizing the product validation process, attention is drawn to additive manufacturing (AM), focusing on the thermoplastic parts printing process by Fused Deposition Modeling (FDM) and Stereolithography (SLA). With this, it would be possible to obtain critical components for the project, integrating them into the product assembly, and performing the necessary tests. This work evaluates the results of mechanical tests performed on specimens obtained by SLA and FDM when compared with the results obtained from injected specimens. Therefore, it was possible to observe a good retention of mechanical properties from AM processing methods, when subject to tensile tests the FDM specimens present a reduction of around 1.61% and 5.33% in relation to yield strength and modulus of elasticity, with less deformation than the plastic injected specimens, and the SLA specimens present more significant reductions in these same proprieties (13.12% and 22.96%), but with a better ductile behavior.

Resumo em Inglês:

ABSTRACT Since the mid-1970s, geopolymer mortars and concretes have been produced through the alkaline activation of mixtures containing natural raw materials or wastes rich in silica (SiO2) and alumina (Al2O3), using a two-part processing method. In general, these inorganic polymers exhibit good mechanical performance, thermal resistance, and tribochemical properties. The literature has demonstrated that mining tailings (dust) from slate dams rich in aluminosilicates can be reused to obtain geopolymer composites through alkaline activation with potassium hydroxide (KOH) or sodium hydroxide (NaOH), or even with other basic aqueous solutions such as sodium silicates. Currently, there is an attempt in the literature to improve the synthesis of geopolymer compounds by acid activation, called silicoaluminophosphates, among the various aqueous phosphate solutions and others described in the literature. Therefore, food-grade phosphoric acid (H3PO4) at a concentration of 85% was selected for this exploratory study. The scope of this research was to evaluate the potential use of slate mining residue as a raw material in the synthesis of geopolymer composites using the two-part method for civil construction applications, such as mortars for the manufacture of auxiliary lightweight paving structures, masonry enclosures, and auxiliary urban elements. The raw material was optimized by grinding in a ball mill for periods of 15 minutes, 2 hours, and 7 hours, until reaching the desired particle size for geopolymerization. The materials were subjected to laser particle size analysis and physicochemical characterization by XRF, XRD, and SEM of both the raw material and the geopolymer specimens (PCs). During the processing of the PCs, the setting time was analyzed, and then their mechanical behavior was evaluated by compression tests at 28 days. The results of the mechanical compressive strength were satisfactory, showing increases in the alkaline mixture mixes (1 and 2), with corresponding values of 100% and 47.33%, respectively. In the acidic mixture, in mixes (1 and 3), strength reached increases of 91% and 93%, indicating potential for application in non-structural masonry. It was concluded that slate residue can be applied in infrastructure, urban sanitation, paving of public roads, and auxiliary paving structures, using geopolymerization techniques.

Resumo em Português:

RESUMO A tecnologia de manufatura aditiva utilizada na fabricação de moldes e machos de areia para produzir peças fundidas em ligas metálicas está em fase inicial de implantação no Brasil. Entre suas vantagens estão a flexibilidade e as capacidades de design complexo, além da ampla gama de combinações de areia e ligantes já disponíveis comercialmente. Essa tecnologia pode ser aplicada em áreas específicas do molde, enquanto outras áreas, mais externas, podem ser fabricadas com processos convencionais de moldagem. Este estudo apresenta o efeito das condições de ambiente controlado (AC) e não controlado (ANC) de temperatura e umidade na estocagem de amostras produzidas por manufatura aditiva com areia e resina furânica, nas propriedades de tração, flexão e permeabilidade. As amostras foram produzidas por manufatura aditiva em camadas de 280 μm de espessura, utilizando areia sílica recoberta com ativador ácido p-toluenossulfônico (máx. 5,0% H2SO4) e resina furânica FB001 da marca ExOne, aplicada na forma de jato nas regiões determinadas pelo projeto que define a forma geométrica das amostras. Os resultados mostraram que a resistência à tração e à flexão aumentaram ao longo do tempo de estocagem, indicando que a resina continua seu processo de polimerização. Na condição de estocagem AC, apresentou melhor resistência à tração e à flexão em comparação à condição ANC, indicando que a umidade interferiu negativamente nos resultados de tração e flexão. Por outro lado, a permeabilidade não apresentou variação significativa entre as duas condições de estocagem das amostras. Observou-se também anisotropia de resistência à tração nas direções XY em relação à direção Z.

Resumo em Inglês:

ABSTRACT Additive manufacturing technology for the production of sand molds and cores used in casting metallic alloy components is in the early stages of implementation in Brazil. Among its advantages are design flexibility, the ability to produce complex geometries, and a wide range of commercially available sand and binder combinations. This technology can be ap-plied to specific areas of the mold, while other, more external regions may be manufactured using conventional molding processes. This study investigates the effect of controlled (AC) and uncontrolled (ANC) environmental conditions specifically temperature and humidity on the storage of samples produced by additive manufacturing using silica sand and furan resin, focusing on tensile strength, flexural strength, and permeability properties. The sam-ples were produced via additive manufacturing in 280 μm-thick layers, using silica sand coated with p-toluenesulfonic acid activator (max. 5.0% H2SO4) and ExOne FB001 furan resin, applied by jetting in regions defined by the geometric design of the samples. The re-sults showed that tensile and flexural strength increased over the storage period, indicating that the resin continues its polymerization process over time. Samples stored under AC conditions exhibited higher tensile and flexural strength compared to those stored under ANC conditions, suggesting that humidity negatively affected the mechanical properties. On the other hand, permeability did not show significant variation between the two storage conditions. Anisotropy in tensile strength was also observed between the XY and Z directions.

Resumo em Inglês:

ABSTRACT This study examines the mechanical recycling of expired Portland cement through fine grinding at four different fineness levels: 390, 450, 550, and 650 m2/kg. To evaluate performance recovery, experimental tests such as compressive strength, calorimetric analysis, and setting time were carried out. The findings indicated that mechanical characteristics and reactivity were improved by increasing fineness. Cumulative heat release increased from 135 to 290 J/g, and compressive strength increased from 15 MPa (REC 390) to 36 MPa (REC 650). Higher fineness did, however, also result in a greater need for energy. REC 550 was determined to be the best formulation by applying the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) decision-making approach with equal weighting, which provides a good balance between energy efficiency and performance. The results support the possibility of recovering expired cement to create useful binders, which would help with waste minimization and environmentally friendly building.

Resumo em Inglês:

ABSTRACT Recycling solid waste is crucial for achieving sustainable development, as it enhances economic efficiency while preserving environmental stability. However, many solid waste image modalities are susceptible to noise and uncertainty, which can compromise the performance of automated waste classification systems. Neutrosophic sets (NS) provide a robust framework for managing such uncertainty by decomposing images into three components: truth (T), indeterminacy (I), and falsity (F). Unlike traditional representations, the NS framework explicitly models ambiguity and vagueness inherent in visual waste data. This study investigates the effectiveness of deep learning (DL) models integrated with the NS framework for solid waste classification using the TrashNet dataset. The original images are transformed into the neutrosophic domain, enabling their representation through these three distinct components. Four DL architectures—DenseNet121, DenseNet169, InceptionV3, and MobileNetV2 are trained on images processed within the neutrosophic environment. The performance of these models is evaluated and compared across both the NS and fuzzy set (FS) domains using key metrics such as accuracy, precision, recall, and F1-score. The experimental outcomes demonstrate that the NS framework outperforms the FS approach, with the neutrosophic falsity component achieving a maximum accuracy of 97.64% using InceptionV3, highlighting its potential for more reliable waste classification in real-world applications. Overall, the proposed neutrosophic–deep learning framework offers a robust and scalable solution for intelligent solid waste management, supporting sustainable smart-city initiatives.

Resumo em Inglês:

ABSTRACT Hybrid Cellular Automata (HCA) are robust computational tools that extend the classical Cellular Automata (CA) framework by integrating both discrete and continuous modeling principles. This hybrid nature enables more accurate, flexible, and efficient simulations of complex microstructural phenomena. In this work, a three-dimensional HCA approach is employed to simulate the recrystallization of metallic materials with anisotropic spheroidal grains, specifically, prolate and oblate morphologies. The proposed model introduces geometric and mathematical formulations that enable control over grain shape and spatial orientation during growth, thus extending previous models limited to spherical symmetry. The implementation is entirely computational, developed in Python, and structured for modularity and efficiency. Several simulations were conducted under varying conditions, including single and multiple nuclei, different grid sizes, and controlled anisotropic orientations. These simulations demonstrate the model’s capacity to generate realistic and heterogeneous microstructures, with adjustable morphological and directional features. Quantitative analyses of grain volumes and growth patterns further validate the model’s precision and consistency. Additionally, the work explores spatial rotation techniques to simulate heterogeneous anisotropic textures within a single matrix, enabling the modeling of complex structures. The flexibility, ease of implementation, and qualitative accuracy of this HCA model establish it as a powerful tool for predictive analysis in computational materials science.

Resumo em Português:

RESUMO Um edifício histórico integra diferentes tipos de alvenaria, texturas e características. Tais características possuem dependência de vários fatores. Por guardar valores culturais, históricos e científicos, os restauros de argamassas históricas não podem ser realizados sem uma minuciosa análise. Portanto, se faz necessário uma caracterização detalhada levando em conta a estrutura da argamassa histórica. O objetivo deste trabalho é a caracterização química e mineralógica de exemplares de argamassas históricas coletados no Convento franciscano localizado na cidade de Ipojuca, estado de Pernambuco, Brasil. Os resultados contribuirão para a reconstituição do traço da argamassa original. Para tanto, foi realizada análise química por via úmida, empregando-se técnicas de gravimetria e titulometria de acordo com o Método IPT, além de ensaios de termogravimetria (TGA). Os resultados apontam para uma argamassa tendo a cal como ligante e agregado silicoso. A análise química sugere que as amostras internas se tratam de argamassas à base de cal hidráulica com traços 1:8,1 e 1:7,5, enquanto as amostras externas argamassas à base de cal magnesiana com traço 1:3, 1:3,2 e 1:5,8. Os resultados podem oferecer uma contribuição significativa para na confecção de uma argamassa de restauro compatível, evitando-se retrabalhos ou manifestações patológicas que descaracterizem o monumento.

Resumo em Inglês:

ABSTRACT Historic buildings integrate diverse masonry types, textures, and characteristics, which depend on various factors. A historical-scientific study is necessary, and its results should inform the formulation of a restoration mortar that avoids negative interactions with pre-existing materials. This study aims is chemical and mineralogical characterization of historic mortar samples collected from the Franciscan Convent in Ipojuca, Pernambuco, Brazil. The results will contribute to the reconstruction of the original binder:aggregate ratio. Chemical analysis was performed using wet chemistry methods, employing gravimetry and titrimetry techniques according to the IPT Method, in addition to thermogravimetric analysis (TGA). The results indicate a mortar with lime as the binder and siliceous aggregate. Chemical analysis suggests that internal samples are hydraulic lime-based mortars with 1:8.1 and 1:7.5 binder:aggregate ratio, while external samples are magnesian lime-based mortars with 1:3, 1:3.2, and 1:5.8 binder:aggregate ratio. The results can provide significant contributions to the development of a compatible restoration mortar, avoiding rework or pathological manifestations that could compromise the monument's integrity.

Resumo em Português:

RESUMO A gestão inadequada de Resíduos Biomédicos Incinerados (RBI) representa um desafio ambiental e de saúde pública global. Paralelamente, a crescente demanda por recursos naturais na construção civil exige alternativas sustentáveis. Especificamente no contexto de Alagoas, Brasil, onde a geração de resíduos de serviços de saúde tem aumentado e a destinação final exige aterros licenciados, a busca por alternativas se torna um desafio urgente. Este estudo investigou a viabilidade tecnológica e ambiental da incorporação de cinzas de RBI em matrizes de concreto, substituindo parcialmente a areia de rio, visando uma solução mútua para a valorização de resíduos e a conservação de agregados naturais. As cinzas, provenientes de uma incineradora de Alagoas que trata diversos tipos de resíduos de serviços de saúde (exceto o grupo C), foram submetidas a caracterizações detalhadas de granulometria, Fluorescência de Raios X (FRX), Difração de Raios X (DRX) e Termogravimetria (TGA). Para a avaliação de desempenho, foram moldados corpos de prova de concreto com substituição de areia por RBI em composições de 0% (referência), 5%, 10%, 15% e 20% em massa. Os resultados revelaram que as cinzas de RBI possuem granulometria predominantemente na faixa de areia média, com partículas menores otimizando os pontos de contato na matriz cimentícia. A análise química por FRX indicou alta proporção de Cálcio (53,232%) e Ferro (19,658%), e um teor limitado de Silício (5,408%), sugerindo baixa atividade pozolânica. A técnica de DRX confirmou a natureza cristalina com a presença de Calcita e Silicatos de Cálcio. Em termos de desempenho mecânico, o concreto com 5% de substituição de areia por RBI manteve a resistência à compressão significativamente próxima ao traço de referência (15,55 MPa vs. 16,89 MPa aos 28 dias). Contudo, o aumento da proporção de RBI (acima de 5%) resultou em uma redução progressiva da resistência e um aumento da porosidade. Isto foi evidenciado pelos ensaios de absorção de água, que mostraram maior absorção em maiores teores de cinzas. A Microscopia Eletrônica de Varredura (MEV) complementou as análises, confirmando a morfologia e distribuição das partículas. Conclui-se que a incorporação de RBI em baixas proporções é tecnicamente promissora para aplicações não estruturais, fornecendo uma rota viável para a gestão sustentável de resíduos perigosos e a inovação em materiais de construção.

Resumo em Inglês:

ABSTRACT Inadequate management of Incinerated Biomedical Waste Ash (IBWA) poses a major challenge for the environment and public health. Simultaneously, the increasing demand for natural resources in civil construction calls for sustainable alternatives. Specifically in the context of Alagoas, Brazil, where healthcare waste production has increased, and where final disposal requires licensed landfills, the search for alternatives becomes pressing. This study investigated the technological and environmental feasibility of incorporating IBWA into concrete matrices, partially replacing river sand. The objective was a dual-benefit solution: hazardous waste valorization and natural aggregate conservation. The IBWA, sourced from an incinerator in Alagoas that treats various types of healthcare waste (with the exception of group C), were subjected to detailed characterization by particle size distribution, X-ray Fluorescence (XRF), X-ray Diffraction (XRD), and Thermogravimetric Analysis (TGA). For performance evaluation, concrete specimens were molded with sand replaced by IBWA at 0% (control), 5%, 10%, 15%, and 20% by mass. The results showed that the IBWA predominantly exhibited particle sizes similar to medium sand, with smaller particles acting to optimize contact points within the cement matrix, serving as a filler. The XRF chemical analysis indicated a high proportion of Calcium (53.232%) and Iron (19.658%), and a limited Silica content (5.408%), suggesting low pozzolanic activity. XRD confirmed the crystalline nature with the presence of Calcite and Calcium Silicates. In terms of mechanical performance, concrete with a 5% replacement of sand with IBWA maintained compressive strength significantly close to the control mix (15.55 MPa vs. 16.89 MPa at 28 days). However, increasing IBWA proportion (above 5%) resulted in a progressive reduction in compressive strength and increased porosity. As a result, water absorption tests indicated higher absorption at greater ash contents. Scanning Electron Microscopy (SEM) complemented the analyses, confirming particle morphology and distribution. The study concluded that the incorporation of IBWA in low proportions is technically promising for non-structural applications. This provides a viable route for sustainable hazardous waste management and innovation in construction materials.

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ABSTRACT SLM AlSi10Mg alloy has good corrosion resistance, oxidation resistance and fatigue resistance, and it is an important material for automobile, aerospace and other industrial fields. In this paper, the mechanical and fatigue properties of SLM AlSi10Mg alloy under different annealing temperatures are investigated by means of MTS fatigue tester, microhardness tester and digital image correlation (DIC) method. The results show that: the fatigue damage evolution laws of DIC characterization and hardness characterization are the same, both of which are composed of stable development stage and rapid damage stage, and the critical inflection point of the damage evolution curve in the DIC strain field from the stable development stage to the rapid damage stage is later than that of the hardness damage evolution curve. The higher the annealing temperature is, the later the damage deformation enters the rapid damage stage, the larger the critical damage factor is, and the stronger the ability of SLM AlSi10Mg alloys to resist fatigue breakage is.

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ABSTRACT The growing demand for sustainable, durable, and crack-resistant construction materials has accelerated research into hybrid Fibre Reinforced Concrete (FRC) systems incorporating Polyvinyl Alcohol (PVA), polyethylene (PE), and steel fibres. Challenges persist in achieving early crack detection and designing optimal FRC mixtures with balanced mechanical and durability properties. This study introduces an Explainable AI-Driven Ant Lion Optimization (ALO) framework that integrates deep learning–based crack detection with intelligent FRC mix design optimization. In the first stage, a Deep Convolutional Neural Network (DCNN) combined with Augmented Gradient-weighted Class Activation Mapping (AugX-Grad-CAM) is employed for precise crack localization and interpretability, achieving an average detection accuracy of 92.4%, with a 28% improvement in detection reliability compared to existing CNN models. In the second stage, the ALO algorithm optimizes the proportions of PVA, PE, and steel fibres to enhance tensile strength (+22%), flexural toughness (+25%), and crack resistance (+27%) relative to standard FRC formulations. The optimized FRC microstructure, analyzed through Scanning Electron Microscopy (SEM), confirms improved fibre–matrix bonding and reduced micro­crack propagation. The proposed framework establishes a closed-loop AI–materials integration, linking real-time crack diagnostics with adaptive material optimization. This synergy between explainable AI and nature-inspired optimization presents a scalable pathway toward intelligent, self-improving, and resilient concrete.

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ABSTRACT This study investigates the combined influence of silica fume and discrete fibers on the mechanical and durability performance of concrete under acidic environments. Experimental data were obtained from 24 cylindrical specimens prepared in the laboratory, incorporating 10% silica fume as a cement replacement and 1.0% total fiber volume of glass, surface-treated jute, and hemp. Data were collected at 7, 14, and 28 days for each mix to evaluate strength development over time. Specimens were exposed to acidic solutions of pH 3 and pH 5 for 28 days to simulate aggressive service conditions. Statistical analysis, including mean, standard deviation, ANOVA, and PBIAS error assessment, was conducted to validate data consistency and model accuracy. The glass fiber–silica fume mix showed the best performance, achieving 54.7 MPa compressive strength and 5.12 MPa tensile strength, representing increases of 26.4% and 28.1% compared with control concrete. PBIAS values of −2.83% (compressive) and −3.12% (tensile) indicated excellent predictive agreement. UPV exceeded 4.6 km·s−1, and sorptivity decreased by 18.5%, confirming a dense and durable microstructure. Overall, the integration of 10% silica fume and glass fiber significantly enhanced acid resistance and strength, making it suitable for wastewater and chemical infrastructure applications.

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ABSTRACT The cutting force, surface roughness, tool life, materials removal rate are generally evaluated by the efficiency of the cutting methods used in the industry. The machining process selected to machine a workpiece providing minimum surface roughness, maximum material removal rate, minimum cutting force, are considered to be highly efficient. However, in an industry, in specific the machining condition, the objective function gives contradictory requirements. In these cases, Multi Criteria Decision Making process is adopted to ensure equal importance for all the objective functions. In this paper, multi-criteria decision making study is presented for machining of steel using milling machine. The weights of the criteria are determined by four different methods, namely; equal weight, Rank Order Centroid (ROC) method, Rank Sum (RS) weighing method and Entropy weight. The Measurement Alternative and Ranking according to COmpromise Solution (MARCOS) method is applied for multi-criteria decision making. The best alternative is evaluated and the effects of ordering the criteria on decision making have been discovered.

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ABSTRACT Dye sensitized solar cells (DSSC) are a third-generation solar cell, composed of dye, photoanode, a counter electrode and a redox electrolyte. The sensitized dye affects the overall efficiency of the cell by the amount of excited dye inside the cell. This work investigated the effect that different time’s absorption of N719 dye causes on a TiO2/ZnO based DSSC. The longer dye sensitized time helped to increase the short-circuit current density and the efficiency of the cell, with optimum time of six hours, for current and four hours for efficiency.

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ABSTRACT Alternatives are needed because conventional reinforcement methods cannot meet modern structural and durability standards. Nonlinear finite element modeling will evaluate the flexural performance of glass fiber reinforced concrete (GFRC), full-scale beams reinforced with steel, FRP, or a hybrid. Billing stress distribution, crack propagation, plastic strain contours of the materials, energy dissipation, and deflections for each reinforcing type assessed the full-scale beams' flexural response and shear performance. The results showed that hybrid beams had the maximum capacity load of 28.1 kN, elongation capacity, and fracture control. Due to localized stress and yield loss, FRP reinforced beams failed catastrophically, while steel reinforced beams failed ductilely and moderately cracked throughout loading. Flexural and shear failure showed that hybrid reinforcement increased energy dissipation and delayed failure in all three trial beams that were analyzed for plastic strain profiles. The von-mises stress analysis showed that stress was lowered and cracking propagated with stress, although hybrid beams showed uniform distribution through composites. This research suggests that fiber reinforced polymer reinforcement with steel reinforcement is a rational, competitive, and beneficial reinforcement for GFRC beams because it distributes stress uniformly throughout the member and extends mechanical performance and life in shear and flexure.

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ABSTRACT This study investigates the use of Recycled Coarse Aggregates (RCA) as a partial or full replacement for Natural Aggregates (NA) in structural concrete, addressing the rising Construction and Demolition (C&D) waste in India. Although environmentally beneficial, RCA use in structural applications is limited due to concerns over strength and durability. To assess its feasibility, bond strength between RCA concrete and steel reinforcement was tested using the RILEM pull-out method and simulated in ANSYS Workbench. Non-Destructive Testing (NDT), particularly Ultrasonic Pulse Velocity (UPV), was used to evaluate compressive strength, dynamic elastic modulus, and durability indicators. Results showed that M30 concrete with 25% RCA outperformed conventional concrete in strength. A 2.3% reduction in bond strength was observed with 16 mm bars, while 100% RCA with 20 mm bars showed a 1.25% improvement. In M50 concrete, up to 50% RCA retained adequate strength, with bond performance influenced by bar diameter. The dynamic elastic modulus was 48% higher than the static value. Acid exposure caused visible surface deterioration, indicating possible durability concerns. Overall, RCA can be effectively used in structural concrete with proper design and quality control. The study also emphasizes the relevance of NDT methods in assessing the performance of RCA concrete.

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ABSTRACT The Measurement Alternative and Ranking according to COmpromise Solution (MARCOS) method is applied for multi-criteria decision making for the selection of optimal process parameters during turning of Al 6063. In this work, turning of 6063 Aluminium is done using a lubricant mixed with Titanium carbide additives. Turning of Aluminium 6063 is carried out as per the design of experiments and L27 orthogonal array is selected according to the Taguchi technique. The input process parameters considered are cutting speed, feed rate, depth of cut and percentage of titanium carbide as additive in the lubricant. The minimization of surface roughness, cutting force and maximization of material removal rate are the objective functions of this research. Different weighting methods are used to determine the weights for the criteria in MARCOS method and ranking of the alternatives and ordering the criteria on decision making have been performed. The results addresses the objective of this research by determining the optimal machining conditions balancing among the conflicting performance measures. Taguchi – MARCOS approach provides a reliable and robust decision making tool for machining parameter optimization and thereby demonstrating the practical applicability of the proposed optimization process.

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ABSTRACT The search for sustainability has led to the increased use of natural fibers, such as sisal. This study aimed to analyze the physical, mechanical, and thermal properties of sisal fibers from Brazil’s semi-arid region, enhancing their use as reinforcement in biocomposites. Tests were performed on density, diameter, moisture content, water absorption, tensile strength, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The fibers had an average density of 1.15 g/cm3, a maximum tensile strength of 242 MPa, a modulus of elasticity of 5,399 MPa, and a maximum deformation of 0.08 mm/mm. Thermogravimetric analysis (TGA/DTG) indicated good thermal stability of the fibers up to approximately 230ºC. The high-water absorption of the fibers highlighted the need for surface treatments to optimize fiber-matrix adhesion. The findings were essential for understanding the properties of sisal grown in northeastern Brazil, highlighting its potential as a reinforcement in biocomposites for developing new biodegradable, environmentally friendly, and high-performance products.

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ABSTRACT Dissimilar AISI 316/AISI 304 stainless steel joints were produced by MIG welding using 308L filler metal to investigate the influence of three controlled heat input levels (0.36, 0.43, and 0.54 kJ/mm) on microstructural evolution and mechanical performances. Heat input was controlled by varying welding current (70–90 A), arc voltage (16–20 V), and argon shielding gas flow rate (8–12 L/min) using high-purity argon (99% Ar). Solidification mode analysis using the Schaeffler-Espy diagram confirmed ferritic-austenitic (FA) solidification with approximately 10 wt.% δ-ferrite in the weld metal. Optical microscopy revealed that increasing heat input from 0.36 to 0.54 kJ/mm promoted dendrite coarsening in the fusion zone (FZ) and significant grain growth in the heat-affected zone (HAZ) of AISI 316, reducing local hardness from approximately 170 HV to 165 HV in the HAZ. Vickers microhardness measurements showed higher values in AISI 304 regions (190–195 HV) compared to AISI 316 (165–170 HV base metal), with peak fusion zone hardness of 180–190 HV at intermediate heat input. Tensile tests demonstrated the highest performance at the lowest heat input (Level 1: 672.5 MPa UTS, 380.9 MPa YS, 62.28% elongation), while the highest heat input (Level 3) resulted in reduced properties (628.4 MPa UTS, 334.9 MPa YS, 56.92% elongation). SEM fractographic analysis of tensile-tested specimens revealed ductile fracture characteristics at low and medium heat inputs, with deep, uniformly distributed dimples. As the heat input increased, the dimple depth decreased, indicating a transition from ductile to mixed-mode fracture. At 0.36 and 0.43 kJ/mm, fracture occurred within the AISI 316 base metal, while at the highest heat input (0.84 kJ/mm) it shifted to the grain-coarsened HAZ of the 316 side, exhibiting shallower dimples and partially brittle features.

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ABSTRACT The development of stable and thermally effective phase change materials (PCMs) is important for upgrading the energy conservation technologies. The minimal thermal conductivity of organic PCMs, like stearic acid, limits their thermal efficiency. This study utilized a novel nano-encapsulated phase change material (NEPCM) containing stearic acid integrated with nanofillers-multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO)- which was encapsulated by polymethyl methacrylate using the mini-emulsion polymerization method. The pivotal aim of the study is to optimize the thermal conductivity of MWCNT-GO hybrid nanomaterials integrated with stearic acid PCM by using Response Surface Methodology (RSM)-Central Composite Design. The optimized values were assessed by experimental designing, quadratic regression model construction, parameter interactions analyzing using ANOVA, and developing response surface plots utilizing the Minitab software. The developed quadratic model resolved the optimum parameters, which were found to be 368.18 nm, 86.82°C, and 3.85 wt% for shell thickness, synthesis temperature, and MWCNT-GO, respectively. By employing the optimal parameters, the thermal conductivity of NEPCM was enhanced 2.9 times than stearic acid. The obtained results indicated that the NEPCM can significantly improve the thermal efficiency of PCMs and demonstrates RSM as an approach for designing highly efficient NEPCMs, which is specific for green building applications.

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ABSTRACT This study compared the fatigue performance of one unmodified and two Brazilian commercial modified binders – SBS copolymer (AC+SBS) and recycled tire rubber (AC+rubber) – with their corresponding dense-graded asphalt mixtures. Linear Amplitude Sweep (LAS) tests at 19°C were conducted in the binders, while Indirect Tension (IDT) tests at 25°C were performed in the mixtures. The fatigue lives of binders (Nf) and mixtures (N) were determined in the LAS and IDT tests, and power correlations were fitted to the data. The AC+rubber showed the highest fatigue lives in both asphalt and mixture scales, and at least good correlations (R2 > 0.83) between N and Nf were found. With respect to the parameter A35 from LAS, it showed reasonable to excellent correlations (R2 values from around 0.70 to 0.96) with the fatigue lives of mixtures. Overall, these findings give support to the use of LAS as an indicator of the fatigue resistance in the laboratory. In addition, the promising outcomes of IDT contribute to its use in the Brazilian mechanistic-empirical pavement design method (MEDINA). Further investigations with field test sections and other modification types of the binder may give new insights and allow comparisons between field and laboratory data.

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VISUAL ABSTRACT

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ABSTRACT This study explores the impact of elevated temperatures on the strengths of concrete samples, including standard mixes and various fiber-wrapped configurations (basalt, aramid, and combinations). Ambient temperature compressive strengths ranged from 21.01 MPa to 21.97 MPa, with minimal differences between standard and fiber-wrapped samples. Exposure to 250°C and 500°C caused significant reductions in compressive strength, with values dropping notably after 3 hours at 500°C. Split tensile strength at ambient temperature varied between 2.77 MPa and 4.04 MPa. Exposure to elevated temperatures resulted in substantial decreases, especially at 500°C after 3 hours, where strengths fell to 0.57–1.6 MPa. Tensile strength of prisms at ambient temperature ranged from 4.55 MPa to 5.37 MPa, decreasing notably after exposure to 500°C, with values dropping to 1.45–2.67 MPa after 3 hours. Fiber wrapping in cubes, cylinders, and prisms particularly with a combination of basalt and aramid strips helped in maintaining relatively higher tensile strengths, although strength reductions were still observed. The adopted mechanical properties were selected as governing parameters for evaluating the integrity of reinforced concrete members under thermal loading. The scope of this study is therefore to establish the potential of a hybrid basalt–aramid FRP wraps as a strengthening strategy for fire-prone concrete structures, providing a pathway towards field-scale applications and code-oriented design guidelines.

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ABSTRACT The practice of disposing of incinerated bottom ash (IBA) in landfills impose serious risk over the environment. Perhaps, the lack of fine aggregates in the building sector emphasize the use of appropriate substitutes made from industrial wastes. The potential use of treated IBA as a fine aggregate alternative in concrete is examined in this study. By varying the IBA replacement ratios and at constant w/c ratio, the impact of IBA was examined. The concrete mixes were made at 0.45 w/c ratio, and the fine aggregate was replaced with 0% to 100% IBA at 30% intervals. The physical and chemical tests of the IBA verified the presence of heavy metals and found that the concentrations were within acceptable constraints. The workability of the concrete mixes containing IBA was assessed, and the concrete properties were measured using water absorption at 7, 28, 56, and 90 days as well as compressive, flexural, and elastic modulus strength at 7, 14, 28, and 56 days. The findings show that substitution of higher proportions of IBA have an impact on workability and show decreased strength with increased water absorption properties. On the other hand, concrete characteristics at all replacement levels tend to improve with increased curing. The TGA investigation reveals the incidence of fewer Ca(OH)2 peaks due to the incomplete dilution of cement matrix, whereas SEM microstructural studies show dense structure with fine aggregates and porous structure with IBA.

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ABSTRACT In this paper, a study has been made to understand the strength and behavior of fabricated Ferro cement elements under four-point bending. The size of the element adopted in this study is 800 mm × 150 mm × 50 mm. A mortar mix 1:1.1 by weight with w/c ratio 0.36 was adopted. Variables of the study include the number of layers of wire mesh. The number of mesh layers varied is 0, 3, 4, 5 and 6. From the test results it was observed that both first crack and ultimate moments were increased with the increase in volume fraction of reinforcement. It was also observed that the crack width is efficiently controlled by the higher volume fraction of mesh reinforcement. The ultimate moment capacity of the Ferro cement elements are calculated by two methods. The first method is based on the concept of conventional reinforced concrete theory and second method is based on the concept of plastic analysis. A comparison of the ultimate moments predicted from elastic and plastic analysis theories with experimental data shows good agreement.

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ABSTRACT The primary objective of incorporating fibers into concrete is to enhance its load-bearing capacity subsequent to cracking, thereby demonstrating its augmented toughness. Additionally, the incorporation of fibers into concrete has been demonstrated to enhance safety, utility, service life, performance, and durability of concrete structures, particularly in terms of crack control. Non-destructive testing are important tools for inspection and monitoring the integrity and service life of reinforced concrete structures. This research evaluated the mechanical performance, electrical resistivity (surface and bulk) and ultrasonic pulse velocity of concrete reinforced with polymeric fibers. Three different volumes (Vf) of copolymer-based fibers (0.5%, 1.0% and 1.5%) were considered. The type of concrete with polyethylene/polypropylene-based fibers was also considered with a Vf of 1.0%. Tests were conducted to determine the material’s compressive strength, modulus of elasticity, and flexural tensile strength, as well as surface electrical resistivity, bulk resistivity, and ultrasonic pulse velocity. A detailed discussion of the results was conducted, with particular reference to statistical analyses, micro-mechanisms and correlated data. Consequently, an increase in Vf had a negative effect on the compressive strength and modulus of elasticity. As expected, there was a significant increase in the residual flexural tensile strength. An increase in Vf tends to reduce resistivity, particularly surface electrical resistivity, while the ultrasonic pulse velocity remains essentially unchanged. The optimum Vf of copolymer-based concrete of this study was determined to be 1%, and the performance of the three types of fibers studied (copolymer-based and polyethylene/polypropylene-based) was found to be “equivalent”. A comprehensive evaluation of the properties revealed that FRC (Fiber-Reinforced Concrete) exhibited distinct advantages, particularly with regard to its residual flexural tensile - strengths.

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ABSTRACT This study investigates the use of defective Vigna radiata (Vr) powder derived from discolored, broken, or expired mung beans unsuitable for consumption as a natural filler to improve the properties of polylactic acid (PLA) for 3D-printing filaments. As an agricultural byproduct, Vr provides a biodegradable and sustainable alternative to synthetic fillers, aiming to enhance the mechanical and functional performance of PLA composites. Eco-friendly PLA/Vr filaments were developed for Fused Deposition Modeling (FDM). Vr powder was prepared by drying, grinding, and sieving, and incorporated into PLA at 1%, 2%, and 3% weight fractions using single screw melt extrusion. The extruded filaments were 3D-printed using FDM on an Ender 3 V2 with optimized settings (nozzle ~200°C, bed 60–70°C) to fabricate test specimens. Mechanical properties such as tensile, flexural, and compressive strength, hardness, and impact resistance were evaluated, while morphological and structural characteristics were analyzed using SEM, XRD, and FTIR. At 1% Vr loading, tensile strength increased by 8.14%, flexural strength by 9.75%, and compressive strength by 7.64% compared to neat PLA. SEM confirmed uniform filler dispersion, while XRD and FTIR indicated enhanced crystallinity. Overall, Vr-reinforced PLA composites demonstrate improved performance making them promising for biomedical and eco-friendly consumer applications.

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ABSTRACT Biodegradable polymers reinforced with natural fillers are increasingly explored as sustainable alternatives to petroleum-based plastics for packaging applications. In this study, banana leaf powder (BLP), an abundant agricultural waste, was used as a reinforcement for polylactic acid (PLA) to fabricate biocomposite films via a solvent casting technique. BLP was incorporated at 0, 5, 10, 15, and 20 wt.%, and the resulting films were characterized for their mechanical, thermal, morphological, and water absorption properties. Fourier transform infrared spectroscopy (FTIR) revealed enhanced hydrogen bonding between the hydroxyl groups of BLP and the ester groups of PLA. Tensile testing (n = 5) showed that the 15 wt.% BLP/PLA composite achieved the highest tensile strength (71.5 ± 1.8 MPa) and elongation at break (8.1 ± 0.4%), representing an improvement of approximately 22% and 224%, respectively, compared to neat PLA. Thermogravimetric analysis indicated improved thermal stability, with the onset degradation temperature increasing from 290 °C for neat PLA to 325 °C for the 15 wt.% BLP composite. SEM analysis confirmed uniform filler dispersion at moderate BLP loadings, while higher contents led to particle agglomeration. Water absorption increased with BLP content due to the hydrophilic nature of the filler. Overall, the results demonstrate that BLP is an effective, low-cost, and sustainable reinforcement for PLA, with 15 wt.% BLP providing an optimal balance between mechanical performance and thermal stability for sustainable packaging applications.

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ABSTRACT The research explores M20 grade concrete performance upgrades through combination methods of cement replacement with ground granulated blast furnace slag (GGBFS) and internal curing usage of superabsorbent polymer (SAP). A combined mix of GGBFS replacing 10% cement content and SAP added at 0.1% and 0.2% and 0.3% weights of cement was used in this research. The research evaluation included testing compressive strength together with flexural strength and Rapid Chloride Penetration Test (RCPT) and carbonation resistance tests. When GGBFS was combined with 10% replacement rate and SAP content set at 0.3% the concrete mixture showed 9% stronger compressive strength and 11% better flexural strength than the standard concrete mix ratio. Internal curing properties of SAP showed effectiveness in minimizing shrinkage behaviour and restricting microcracks thus suggesting potential benefits for improving crack resistance through crack arrest. The addition of GGBFS in concrete mixtures reduced hydration heat thus reducing the potential for thermal cracks when used for mass concrete applications. By using GGBFS the construction process achieved two sustainability goals: it lowered cement usage and produced reduced CO2 emissions. The combined usage of GGBFS with plastic bags optimizes concrete structure retention while maximising its long-term durability so it can withstand harsh environmental conditions.

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ABSTRACT The demand for high-performance composite materials with improved mechanical properties and durability has led to considerable research into the reinforcement of conventional materials with nanoparticles. In this work, the influence of TiO2 nanoparticles on the mechanical properties of Kevlar fiber-reinforced epoxy composites was studied. The main goal was to enhance the tensile strength, fatigue resistance, hardness, and water absorption of the composite material for advanced engineering applications. The composites were prepared using the hand layup technique, in which chopped Kevlar fibers with a length of 5 cm were reinforced in an epoxy matrix containing preheated TiO2; nanoparticles. The nanoparticles were incorporated at three different weight fractions (1%, 3%, and 5%) to investigate the effect of TiO2 loading on the mechanical and durability properties of the composite material. Mechanical characterization was carried out through tensile, fatigue, and hardness tests, while the microstructural features were examined using Scanning Electron Microscopy (SEM). The results confirmed a significant improvement in the mechanical performance of the composites, with the 5 wt.% TiO2-reinforced composite exhibiting the highest tensile strength of 350 MPa. Notably, this composite also demonstrated superior fatigue performance, sustaining up to 100,000 cycles without failure. These enhanced properties indicate that the developed composites have strong potential for aerospace, automotive, and defense applications.

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ABSTRACT High reclaimed asphalt pavement (RAP) contents in recycled hot-mix asphalt (RHMA) provide economic and environmental benefits but face performance and compaction challenges. This study compared refined decomposition (RD) and roll crushing (RC) for 0%, 30%, 50%, and 70% RAP mixtures. Mix design, gyratory-compaction indices, and performance tests were conducted. Results show that, Compared with RC-RAP, RD-RAP mixtures showed higher Marshall stability, lower air voids, and higher voids filled with asphalt (VFA). At equal RAP contents, optimum asphalt content (OAC) decreased by 0.1%–0.3%, and the compaction energy index (CEI) fell by 13.95%–31.58%, with greater reduction at higher RAP. In terms of road performance, RD-RAP exhibited slightly lower rutting resistance but higher moisture and cracking resistance: TSR increased by 6.37%–10.41%, fracture energy by 11.59%–18.14%. RD-RAP at 70% outperformed RC-RAP at 50%. The dynamic modulus of RD-RAP increased monotonically with RAP, while RC-RAP peaked at 50%. Overall, refined decomposition alleviates compaction and cracking limitations, enabling RAP content up to 70% and offering technical guidance for high-RAP application.

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ABSTRACT Graphite-phase carbon nitride (gC₃N₄) is a two dimensional semiconductor material known for its tunable surface acidity/basicity, structural stability, low cost, and facile synthesis. The quaternary composite catalyst covers a broader visible light spectrum, significantly enhancing light utilization efficiency. This leads to more efficient generation of photo generated electron–hole pairs, thereby supplying abundant active species for degradation reactions.” By preparing g-C3N4/BiOI as a precursor and then fabricating the Ag/Ag3PO4-g-C3N4/BiOI quaternary photocatalyst, the photocatalytic performance was evaluated by degrading two typical water pollutants—rhodamine B (RhB) and ciprofloxacin (CIP)—under visible light. The structure and properties of the samples were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), and elemental distribution analysis, and the possible catalytic degradation mechanism was further analyzed. Among the gC₃N₄/BiOI precursors, CB3 showed the best degradation performance, achieving efficiencies of 93.3% for RhB (20 mg/L) and 83.3% for CIP (10 mg/L). Subsequently, Ag3PO4 was composited onto the CB3 precursor via the sedimentation method, and the quaternary composite was treated with photoreduction. When the photoreduction time was 20 min, the resulting 20 min Ag/Ag3PO4-CB3 showed the best catalytic activity: its degradation efficiencies for 20 mg/L RhB and 10 mg/L CIP were further enhanced to 97.0% and 90.2%, respectively. Cyclic degradation experiments further confirmed the excellent stability of the catalysts. The enhanced performance of the quaternary photocatalyst is attributed to the formation of heterojunctions (p-n junction between g-C3N4/BiOI and Z-scheme heterojunction between Ag3PO4 and g-C3N4) and the localized surface plasmon resonance (LSPR) effect of AgO. These structures efficiently promote the separation of photogenerated electron-hole pairs, extend the lifetime of photogenerated carriers, and reduce photocorrosion, thereby significantly improving the visible-light photocatalytic activity and stability.

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ABSTRACT The present study aims to compare the characteristic values of shear strength parallel to grain obtained through different test methods described in Documents 3 [1] and 4 [2] of ABNT NBR 7190:2022. Compression and shear parallel to grain tests were carried out on specimens from five Brazilian wood species, in order to classify the batches according to their compression strength, to compare the test methods for determining shear strength parallel to grain, as established in the referred documents and evaluating the relationships between shear and compression strengths parallel to grain proposed by the Brazilian standard. The experimental program used batches composed of thirty-six specimens, twelve of which were assigned to compression parallel to grain tests and determination of apparent density, and the remaining twenty-four to shear parallel to grain tests, with twelve used for each test method. Strength characteristic values were determined, statistical equivalence between the methodologies was evaluated, and the existence of a correlation between compression and shear was verified. The results show that the methodology of Document 3 [1] provides significantly higher strength values than those obtained with the methodology described in Document 4 [2], and that there is no statistical equivalence between the two test methods.

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ABSTRACT Cerium oxide nanoparticles (CeNPs) are one of the most promising metal oxide nanoparticles, with a wide range of applications in the fields of environment, energy, industry, agriculture and biomedical sciences. Cerium oxide nanoparticles (CeNPs) also called as nanoceria was synthesized by precipitation method using two different precursors and characterized by X-ray diffraction (XRD) analysis, FTIR, SEM/EDX and DRS-UV-Visible spectroscopy for the structural, compositional, surface morphological and optical property studies. X-ray diffraction studies revealed that the crystallite structure of the ceria nanoparticles was cubic fluorite like with the crystallite size calculated (using the Debye-sherrer formula) was 5.1 nm for pure ceria nanoparticles and 2.8 nm for surfactant CTAB (cetyltrimethylammonium bromide) assisted CeNPs. As per the results of the EDX compositional analysis, the weight percent content of Ce and O in the formed cerium oxide nanoparticles was 78.7% and 21.3% (pure CeO2) and 79.3% and 20.7% (surfactant CTAB assisted nanoCeO2), respectively. SEM analysis confirmed the uniform distribution of CeNPs and the nanocube-like shape of CeNPs formed by the precipitation method. DRS-UV-Visible spectral studies shows that, pure ceria and surfactant assisted ceria exhibit UV-Visible absorption in the range of 320 nm to 346 nm and band gap energy values ranging from 2.4 to 2.6 eV. Surfactant assisted nanoceria shows absorption shifts to the visible region, and the band gap energy values decrease when compared to bulk ceria (Eg = 3.19 eV). The effect of surfactant CTAB on crystallite size and agglomeration, as well as increasing CeO2 product formation, has been observed.

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ABSTRACT This research investigates the influence of quartz sand and alccofine on the mechanical and durability performance of concrete. Quartz sand was used to replace natural fine aggregate in various percentages (0%, 25%, 50%, 75%, and 100%), while alccofine was added as a replacement to cement by 10%. The experimental plan consisted of testing for compressive, split tensile, and flexural strength and durability tests under hydrochloric acid and sulfuric acid exposure. The test results indicated that mix AQ25, consisting of 25% quartz sand and 10% alccofine, was the best performing mix, with a 28-day compressive strength of 61.27 MPa, which is an increase of 38% over conventional concrete. Mix AQ25 also resulted in higher values of split tensile (3.52 MPa) and flexural strength (6.3 MPa), reflecting improved characteristics of ITZ. Tests for acid resistance also demonstrated a higher residual strength and less deterioration for quartz sand-based mixes, with AQ25 maintaining strengths of 59.55 MPa after 1% HCl and 53.25 MPa after 1% H2SO4 attack. SEM observations also showed improved microstructural density, superior formation of C-S-H gel, and reduced porosity for optimized mixes. In general, the blending of alccofine with 25% quartz sand increases the strength and durability of concrete considerably.

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ABSTRACT Austenite reversion, α'-martensite → γR-austenite reverted phase transformation, in AISI 304 steel was investigated. All the specimens had been subjected to a one-hour austenitizing heat treatment at 1050 °C in vacuum and with air cooling. Then, they were laminated at –70 °C, with a resulting total reduction of 63%. Finally, the samples thus generated were individually subjected to thermal annealing treatments for 1 hour, with increasing temperatures between 300 °C and 950 °C. In addition to microstructural changes and Vickers microhardness, the reversal process was studied through magnetic measurements: magnetic saturation and magnetic Barkhausen Noise (MBN). These measurements were carried out at room temperature. A temporal analysis of the MBN signals was done and their RMS (Root Mean Square) values were calculated. A similar trend was observed for the RMS of the MBN and the α' martensite contents, beyond the intrinsic differences in the techniques used to perform the measurements. Both techniques allow observing the evolution of the content of α' martensite or ferromagnetic phase as the temperature of the thermal reversion treatment increases.

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ABSTRACT To elucidate the multiscale mechanisms governing performance formation in high–reclaimed asphalt pavement (RAP) mixtures, this study integrates macro-, meso-, and microscale analyses into a unified framework. Based on large-sample statistical analysis, the concept of RAP “inherent gradation” is proposed, demonstrating consistent convergence toward the upper limit of the AC-13 gradation. A quantitative clustering degree index (C, average ≈44%) is introduced, identifying clustering as the key structural origin of systematic gradation coarsening and void-structure destabilization. An internal-porosity–based discriminant model, combined with a water-to-asphalt film-thickness conversion (ha = 1.77hw), enables accurate prediction of the optimum asphalt content (OAC), with deviations within ±5%. Microscale chemical and morphological analyses indicate that aging-induced increases in interfacial tension act as a dominant barrier to binder compatibility, whereas moderate incorporation of Trinidad Lake Asphalt (TLA, ~40%) effectively reduces interfacial energy and improves wetting behavior. Building on these findings, a “Structure–Void–Interface–Performance” multiscale interaction model is established and experimentally validated, revealing a dual-control mechanism: high-temperature performance can be enhanced through meso–micro synergistic regulation, while low-temperature and fatigue performance remain constrained by aged-binder rheology. The results provide a theoretical basis and practical guidance for refined high-RAP mixture design.

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ABSTRACT Artificial Neural Networks (ANNs) offer a compelling alternative, yet they rely significantly on varied and high-quality datasets. The scarcity of experimental data, particularly for fibre-reinforced High-Strength Concrete (HSC), limits the generalization and dependability of models. Therefore, the key challenge lies in creating resilient ANN architectures capable of accurately predicting various mechanical properties of HSC. This study develops an ANN model in MATLAB to predict the mechanical properties of HSC using input parameters such as cement, aggregates, mineral admixtures, chemical admixtures, steel fibres, glass fibres, and water. Seventy-two experimental results were employed for training and testing, and the model’s predictions were validated against experimental data. The ANN demonstrated high accuracy in estimating compressive strength, split tensile strength, and flexural strength of HSC with varying fibre contents and water–cement ratios. Strong agreement was observed between predicted and experimental values, with coefficients of determination (R2) of 0.98 for compressive strength, 0.93 for split tensile strength, and 0.93 for flexural strength. These findings highlight the potential of ANN-based approaches as reliable tools for modelling and predicting the mechanical performance of high-strength concrete.

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ABSTRACT Unidirectional carbon/epoxy laminates form the basis of weight-sensitive structures, yet tensile allowables depend on strain metrology and fiber-orientation traceability. A locked tensile workflow that removes compliance bias and enforces channel synchronization for orientation-resolved property extraction has not been previously reported. This study develops a compliance-aware, time-synchronized tensile evaluation for 0°, 45°, and 90° coupons taken from a single 16 panel. A 16-ply laminate with fiber volume fraction near 55% was fabricated. Coupons were tabbed and tested quasi-statically with extensometry, crosshead records were corrected by rigid-coupon calibration, and strength scatter was modeled using two-parameter Weibull statistics with bootstrap uncertainty for energy metrics. Anisotropy is large: the 0° modulus was 66.6–66.7 GPa and strength was ~800 MPa, the 45° modulus was ~15.0 GPa with ~150 MPa strength and ~3.0% failure strain, and the 90° modulus was 3.3–3.36 GPa with ~50 MPa strength. Energy absorption is orientation dependent; strain-energy density to failure was 4.59 MJ m−3 at 0°, 3.50 MJ m−3 at 45°, and 0.36 MJ m−3 at 90°. The processing chain yields design-ready properties and reliability descriptors suitable for lamina-level modeling and combined-stress assessment. Future work targets hygrothermal conditioning, full-field strain mapping, and strain-rate coverage from 10−5 to 10−1 s−1.

Resumo em Inglês:

ABSTRACT Aluminum–boron carbide (Al–B4C) composites have shown promise as lightweight, wear-resistant materials; however, weak particle–matrix bonding, melt-stage clustering, and unstable friction have limited reliability. Addressing these linked defects is essential for high-strength components. Prior work did not vary the interface design, dispersion, and solid lubrication simultaneously within a single process history, leaving the synergy untested. This study aimed to determine whether engineered interphases produced by ultrasonic dispersion and trace 2D lubricants increased the tensile strength and stabilised sliding wear. A balanced factorial crossed interphase route (electroless Ni–P, sol-gel TiO2→TiC, in situ Ti/B), ultrasonication on/off, and graphene or hBN at 0–1.0 wt. %; XRD/EDS, interphase-thickness and dispersion statistics, and quantitative masks for pull-out and tribofilms supported the analysis. Tensile and pin-on-disk tests yielded wear, friction, and UTS. Graphene-bearing hybrids with Ni–P or in-situ Ti/B maintained UTS ≥330 MPa and reduced wear to ≤0.2 mm3·m−1 with steady friction near 0.20; transfer films reached 65–80% coverage and 95–105 nm median thickness. Ultrasonics sharpened the TiC interfacial coherence and reduced particle pull-out. The results indicated that metallurgical or ceramic interphases paired with graphene produced a low-wear, high energy efficiency on the strength–wear map and surpassed states.

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ABSTRACT The chalcogenide phase-change material Ge2Sb2Te5 (GST) is paramount for developing next-generation reconfigurable photonic devices, yet its performance is critically dependent on thin-film quality. This work presents a systematic investigation into the influence of radio-frequency (RF) magnetron sputtering parameters—specifically argon (Ar) working pressure and substrate temperature—on the structural, chemical, optical, and kinetic properties of GST thin films. Films were deposited on SiO2/Si substrates under varying Ar pressures (0.4–3.0 Pa) and substrate temperatures (Room Temperature–160 °C). Comprehensive material characterization was performed using a suite of advanced analytical techniques. Results indicate that increasing Ar pressure leads to the formation of films with lower density and higher porosity, as confirmed by scanning electron microscopy analysis. This porous microstructure facilitates a lower crystallization temperature and faster crystallization dynamics, with switching times on the order of tens of picoseconds observed via time-resolved pump-probe reflectivity. However, this enhancement in switching speed is accompanied by a significant reduction in the optical contrast, a key figure of merit for photonic applications. Conversely, elevating the substrate temperature to an optimal 80 °C during deposition produces dense, pore-free amorphous films with a density of 6.16 g/cm3, only 1.5% lower than the crystalline phase. These films exhibit superior thermal stability and a maximized refractive index contrast (Δn) at telecommunication wavelengths. X-ray photoelectron spectroscopy confirmed that a protective capping layer is essential to prevent the rapid surface oxidation of Ge. These findings establish a clear process-structure-property-performance relationship, providing a crucial framework for tuning GST film properties to meet the divergent demands of high-speed, low-power optical memories versus high-performance, low-loss tunable photonic components.

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ABSTRACT To improve the monitoring of structural health and efficiency zoning in building structures, the research proposes a hybrid nano-engineered structure for Functionally Graded Concrete (FNGC) coupled with Multi-Zone Failure Analysis (MZFA). Existing concrete structures face limitations in longevity, fracture durability, and targeted stress resistance often resulting in early structural failures and costly repairs. The proposed technique incorporates nano-engineered materials, such as nanotechnology-based additives, graphene and hybrid fillers within functionally graded layers. This enhances strength distribution, electrical conductivity and fracture propagation control across different architectural zones. The systemic MZFA framework provides a reliable zoning system for maintenance planning by analysing stress–strain behaviours and signal responses to detect and classify localized failure points. The primary goal is to establish a robust, self-sensing material technology capable of early defect detection and extended service life. Findings demonstrate that the proposed hybrid FNGC outperforms existing composites in terms of generalization, stress durability, and overall strength in crack detection. This approach paves the way for the development of smart, sustainable, and autonomous concrete components for next-generation structures.

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ABSTRACT This research examines the compressive strength performance of environmentally friendly geopolymer concrete prepared with fly ash, ground granulated blast furnace slag (GGBS), biochar, and nano, cellulose fibers, facilitated by a machine, learning, based strength prediction. 28 geopolymer mixes were prepared with fixed activators parameters and tested under both heat, curing and ambient, curing conditions at 7, 14, and 28 days. The experimental results augment that slag, rich mixes (>72% GGBS) in combination with moderate biochar content (46%) and nano, cellulose fibers (0.6–1.0%) reached compressive strengths of 60–61 MPa under ambient curing, which are equal to those of heat, cured systems. To facilitate rational mix optimization, machine learning models like Artificial Neural Networks (ANN), XGBoost, Random Forest, and Linear Regression were created using binder composition as input variables. Of these, ANN had the highest predictive accuracy (R = 0.87, MAE = 4.91 MPa), followed by XGBoost (R = 0.85). Residual analysis and ANOVA were used for statistical validation of the nonlinear models’ robustness. The results demonstrate that the use of bio, based additives in combination with ML, assisted prediction can produce high, strength ambient, cured geopolymer concrete, thus, providing a feasible solution for low, carbon and resource, efficient construction.

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ABSTRACT The transition toward a circular economy has encouraged the construction sector to adopt more sustainable material solutions. In this context, the reuse of industrial polymeric waste in cementitious mortars represents a promising approach that combines environmental and economic benefits by reducing waste incineration and preserving virgin raw materials. This study investigated the feasibility of partially replacing fine aggregates with white water sludge, a byproduct obtained after flocculation and filtration through a filter press during the washing of polymer resin reactors. The polymeric waste was dehydrated, granulated, and characterized to reproduce the particle size distribution of a reference medium sand. High-strength mortars were produced with volumetric sand replacement levels of 5, 10, 15, and 20 vol.%. Consistency and setting time (Vicat) tests were performed in the fresh state. After 28 days of curing, the specimens were evaluated in terms of microstructure using scanning electron microscopy, density, water absorption, compressive strength, and thermoacoustic behavior. The incorporation of polymeric waste caused a gradual reduction in density, indicating potential for lightweight composites. Although compressive strength decreased with increasing replacement, values remained suitable for non-structural applications, including cladding panels and sealing blocks. Functionally, waste addition improved sound attenuation and thermal insulation. This confirms practical feasibility.

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ABSTRACT This study investigates the development of a novel iron carbonate binder, utilizing red mud, an industrial byproduct of aluminum production, as a replacement for traditional components such as fly ash. This study compares the performance of binders made with raw, unsintered red mud (USRM) with those made with red mud that has been thermally activated by sintering at 750°C (SRM). The results demonstrate that sintering pre-treatment is a critical and transformative step. The SRM binder achieved a 28-day compressive strength of 24.12 MPa, a 72.5% improvement over the 13.98 MPa strength of the USRM binder. Furthermore, the SRM binder exhibited excellent long-term stability, maintaining its strength for 90 days, whereas the USRM binder showed lower strength than the SRM samples, indicating potential durability issues. Microstructural analysis via scanning electron microscopy (SEM) revealed that sintering enabled the formation of a dense, robust, and composite binder matrix, characterized by the presence of stable and cohesive calcium carbonate. In contrast, the USRM binder forms a porous, weakly consolidated structure. X-ray diffraction (XRD) analysis confirmed that sintering activated the red mud’s mineralogy, creating reactive cementitious phases essential for superior performance. Thermogravimetric analysis (TGA) indicated higher mass loss in unsintered red mud due to the presence of thermally unstable hydrated phases. In contrast, sintered red mud exhibited reduced mass loss and improved thermal stability, confirming phase transformation during sintering.

Resumo em Português:

RESUMO A busca por materiais sustentáveis na construção civil tem incentivado o desenvolvimento de soluções baseadas no aproveitamento de resíduos lignocelulósicos. Neste estudo foram produzidos e caracterizados painéis de partículas fabricados a partir de resíduos de madeira de Pinus sp. tratados com CCB e adesivo poliuretano à base de óleo de mamona. Avaliou-se a influência da espessura (10 mm e 20 mm) e da pressão de prensagem (2,5 MPa e 4 MPa) sobre propriedades termoacústicas, térmicas, morfológicas e mecânicas, comparando-as a requisitos normativos. Os painéis apresentaram desempenho adequado em absorção sonora e condutividade térmica, destacando-se aqueles de maior espessura nas baixas frequências. As análises térmicas e porosimétrica confirmaram a influência da pressão de prensagem na porosidade e na estabilidade térmica. As propriedades mecânicas atenderam aos limites normativos para painéis de baixa densidade. Entre os tratamentos avaliados, destacaram-se Tr4 (20 mm; 4 MPa) e Tr1 (10 mm; 2,5 MPa) pelas melhores combinações de desempenho termoacústico e térmico. Os resultados indicam que os painéis produzidos apresentam potencial para aplicação como elementos isolantes em sistemas construtivos leves, reforçando o aproveitamento de resíduos tratados com CCB e o uso de adesivo renovável como estratégia de sustentabilidade.

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Abstract The growing demand for sustainable construction materials has driven the development of solutions that valorize lignocellulosic waste. In this study, particleboards were produced and characterized using residues of Pinus sp. wood treated with CCB and bonded with castor-oil-based polyurethane. The influence of thickness (10 mm and 20 mm) and pressing pressure (2.5 MPa and 4 MPa) on thermoacoustic, thermal, morphological, and mechanical properties was evaluated and compared with technical standards. The panels showed suitable performance in terms of sound absorption and thermal conductivity, with the thicker boards showing superior absorption at low frequencies. Thermal and porosimetric analyses confirmed the influence of pressing pressure on porosity and thermal stability. The mechanical properties met the minimum requirements for low-density particleboards. Among the treatments evaluated, Tr4 (20 mm; 4 MPa) and Tr1 (10 mm; 2.5 MPa) presented the best combinations of thermoacoustic and thermal performance. The results indicate that the developed panels have potential for use as insulating elements in lightweight construction systems, reinforcing the valorization of CCB-treated wood residues and the use of renewable adhesive sources as a sustainability strategy.

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ABSTRACT The use of nuclear technologies has increased worldwide, leading to a continuous rise in radioactive waste generation. In Brazil, the National Nuclear Energy Commission (CNEN) faces growing challenges related to the safe management and disposal of radioactive waste from energy production, industrial, medical, security, and research activities. Because some waste remains hazardous for thousands of years, developing disposal solutions that protect both the environment and human health is essential. Current efforts focus on designing facilities suitable for disused sealed radioactive sources, which are not fully covered by the Brazilian near-surface repository project for low- and intermediate-level waste, Centro Tecnológico Nuclear e Ambiental (CENTENA). Although CENTENA does not include deep borehole disposal, this study examines this concept as a technically feasible complementary solution for the long-term isolation of disused sealed sources. To support container material selection for such disposal systems, a comparative electrochemical evaluation of stainless steels 316L, 2304, and 2205 was conducted in saline medium, assessing their corrosion resistance under conditions relevant to deep borehole environments. The results contribute to identifying suitable materials for long-term containment applications.

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ABSTRACT This study investigates the mechanical and flexural performance of reinforced concrete beams incorporating copper slag (CS), cupola slag (CPS), and metakaolin (MK) as partial replacements for fine aggregate and cement, respectively. Six concrete mixtures were prepared and tested, including a conventional control mix (T1) and five modified mixtures with varying replacement levels. The optimized mixture (T6) incorporated 10% CS, 10% CPS, and 10% MK. Experimental results revealed that increased slag content progressively reduced workability, with slump values declining from 133 mm in T1 to 111 mm in T6. Despite reduced workability, mechanical performance testing demonstrated that T6 exhibited superior properties, achieving a 28-day compressive strength of 56.85 MPa—approximately 22.9% higher than conventional concrete. This enhancement is attributed to the synergistic effects of metakaolin’s pozzolanic reactivity, improved particle packing density, and the angular morphology of slag particles, which collectively refined the microstructure. These microstructural improvements were manifested in enhanced flexural behavior, with T6 demonstrating higher first-crack load, ultimate load capacity, ductility index, and energy absorption capacity compared to the control specimen. Finite element analysis (FEA) validated the experimental observations, showing good agreement with the measured load-deflection response. The findings demonstrate that industrial by-products can simultaneously enhance structural performance.

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ABSTRACT Enhancing the freeze–thaw durability of cementitious materials is a key challenge for sustainable construction, particularly in cold-climate applications. Within the broader research field of fiber-reinforced cementitious composites, this study contributes to the ongoing shift toward eco-friendly reinforcement strategies by comparatively evaluating natural plant-based fibers and conventional synthetic fibers. The influence of date palm, dis, alfa, hemp, and polypropylene fibers on the freeze–thaw resistance of metakaolin-based mortars was systematically investigated. Six mortar formulations were tested, each containing fibers at 0.1% by total volume. Compressive and flexural strengths, porosity, dynamic elastic modulus, and thermal conductivity were evaluated before and after freeze-thaw cycles. Results showed polypropylene fibers provided high initial compressive strength (~62 MPa), though significant stiffness reduction (~16%) occurred after cycling. Hemp fibers initially delivered superior flexural strength (~7.5 MPa) but exhibited substantial degradation (~32% loss) after 120 cycles. Alfa and date palm fibers presented intermediate performance with moderate mechanical deterioration, whereas dis fibers maintained relatively stable compressive strength (~45 MPa). Natural fibers generally increased porosity post-cycling but showed reduced thermal conductivity, reflecting structural damage. Overall, the study confirms that fiber incorporation significantly influences the freeze-thaw durability of mortars, with polypropylene fibers offering enhanced long-term stability compared to natural alternatives.

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Abstract This preliminary study investigated the effects of the multiple recycling process (up to three recycling cycles) on the performance characteristics of recycled asphalt mixture containing reclaimed asphalt pavement (RAP), both at the binder and mixture levels. This research built on prior studies from Finland and utilized lab experiments to thoroughly examine these effects. Firstly, loose asphalt mixtures were artificially aged to produce RAP aged once, twice, and three times. Subsequently, a series of Stone Matrix Asphalt (SMA) 16 mixtures were prepared using 50% artificially aged RAP, 70/100 binder, and cellulose fiber, experiencing various levels of recycling cycle. The asphalt mixtures were evaluated for moisture susceptibility, cracking resistance in the low temperatures, and resistance to abrasion due to studded tires. Additionally, dynamic rheological behavior and chemical property changes were tested on asphalt binders, both fresh and aged, through three cycles, which were extracted from their respective mixtures. Results indicated that as recycling iterations progressed, the asphalt mixtures showed improved moisture susceptibility and enhanced resistance to abrasion from studded tires. Although one cycle of recycling had a minimal impact on the low-temperature fracture performance of asphalt mixtures, the fracture energy decreased after three cycles. Regarding asphalt binders, the escalation in recycling iterations improved the high-temperature performance but detrimentally affected fatigue properties. These results support multiple recycling of RAP for Nordic cold-climate surface layers, especially where studded-tire abrasion is critical. Recycling beyond two cycles may increase the risk of low-temperature cracking and require mitigation.

Resumo em Inglês:

ABSTRACT The construction sector demands materials that combine mechanical performance and sustainability. This study evaluates the tensile behavior of polymer composites reinforced with glass fibers (200 GSM) and jute fibers (245 GSM) across six configurations: GGG, JJJ, GGJ, GJG, JJG, JGJ. Unlike research focused on structural components, this study advances by characterizing the composite material in isolation. Tensile tests, conducted according to ASTM D3039 standards, indicated that pure glass (GGG) and jute (JJJ) composites exhibited tensile strengths of 283.37 MPa and 24.46 MPa, with elastic moduli of 6.64 GPa and 1.01 GPa, respectively. Among the hybrids, the GGJ configuration demonstrated the optimal balance between performance and sustainability, achieving a tensile strength of 113.22 MPa and an elastic modulus of 2.53 GPa. This represents a reduction of approximately 60% in strength compared to GGG, yet an increase of over 250% relative to JJJ. Fracture analysis revealed fiber rupture and limited interfacial adhesion between the reinforcements. The GGJ composite is suitable for applications such as cladding panels, partitions, and street furniture. By proposing the partial replacement of synthetic materials in civil construction, this research contributes to SDGs 9 (Industry, Innovation, and Infrastructure), 11 (Sustainable Cities and Communities), and 12 (Responsible Consumption and Production).

Resumo em Inglês:

ABSTRACT The shear key is a connection commonly used in structures built with precast concrete elements. Its use is based on the assumption that adding grout and interlocking the beam-column interface through surface roughness (shear key) can increase the maximum load capacity of the structure, as it relieves part of the load from the corbel. However, the extent of this enhancement remains unclear due to the limited number of systematic studies addressing the structural behavior of such connections. This research evaluated the influence of shear key rib width, beam-column spacing, and beam dimensions on increasing the maximum load. This objective was achieved through a parametric study developed with 35 numerical simulations. The results showed that the presence of the shear key significantly increased the maximum strength. It was found that rib width and beam-column spacing did not significantly impact strength. On the other hand, the beam length proved to be a relevant variable, with its reduction increasing the maximum load. In this context, the beam with the best performance was the 3.80 m beam, for which the presence of the shear key resulted in a 36.70% increase in maximum load compared to the model without it.

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Abstract This study is focused on optimization of the biogas upgradation process by using ionic liquid–embedded polyethersulfone (PES) membranes. Process optimization using response surface methodology (RSM) via central composite design (CCD) was conducted to model and optimize the synthesis and separation performance of these membranes. The membranes were synthesized with varying loadings of [emim][Tf2N] ionic liquid by the solution casting technique. Feed pressure and ionic liquid loading were taken as the independent variables, whereas CO2 permeability, CH4 permeability, and CO2/CH4 selectivity were chosen as the process responses. At optimum IL concentration (20%) and feed pressure (5 bar), CO2 permeability of PES/[emim][Tf2N] membrane was found to be 119.45 barrer with CO2/CH4 selectivity of 31.07 and overall desirability of 0.52. From SEM analysis, a dense and defect-free structure of PES/[emim][Tf2N] was observed, which confirmed successful incorporation of the ionic liquid within the polymer matrix. Similarly, uniform distribution of [emim][Tf2N] ionic liquid in PES matrix was confirmed by EDX analysis. These results confirm that PES/[emim][Tf2N] membranes have a huge potential to upgrade biogas and enrich biomethane for circular bioeconomy and renewable energy goals.

Resumo em Inglês:

ABSTRACT Prefabricated concrete construction demands precise dimensional accuracy at structural joints for safety and performance; therefore, reliable as-built verification is required for construction quality assurance. A joint-level BIM-aligned ground-truth-validated framework was developed to quantitatively compare terrestrial LiDAR and UAV-based photogrammetry for structural joint verification in prefabricated concrete assemblies. A full-scale prefabricated concrete mock-up was surveyed using both sensing modalities, and point clouds were registered to a BIM reference model. Deviation heatmaps, node-level errors, local point density metrics, longitudinal deviation profiles, and acquisition-plus-processing time requirements were derived. LiDAR was shown to provide highly accurate mapping, with over 85% of surface points within ±1 mm of BIM geometry and joint mean deviations of 1.8–3.2 mm, whereas photogrammetry exhibited joint mean deviations of 2.5–6.7 mm, with some local peaks up to +5 mm. Using independently validated accuracy bounds and effort trade-offs that support method selection for prefabricated construction projects, this framework was shown to advance QA/QC practice by enabling tolerance-focused scan-to-BIM verification in connection-critical regions.

Resumo em Inglês:

ABSTRACT Determining the weights of criteria is an essential task when ranking alternative options, especially in contexts where multiple criteria are used to characterize each alternative. The LOgarithmic DEcomposition of Criteria Importance (LODECI) is a weighting methodology known for its advantage of analyzing criterion importance based on the intensity of contrast among all alternatives with respect to each criterion. Nevertheless, the existing data normalization technique utilized within the original LODECI method-specifically, the Linear normalization method, becomes infeasible in certain scenarios. This limitation effectively prevents the use of the LODECI method for criteria weight calculation in those specific cases. To broaden the applicability of this methodology, the present research was undertaken to identify suitable alternative data normalization techniques that can be successfully integrated with LODECI, replacing the standard Linear method. Three normalization methods were considered for combination with LODECI: the Vector normalization method, the Weitendorf method, and the Enhanced accuracy method. The investigation into which of these three normalization methods could replace the Linear method for integration with LODECI was carried out using four distinct examples. The results unequivocally verified that the Vector normalization method is a viable substitute for the Linear method when coupled with LODECI.

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ABSTRACT This study compiles and analyzes 376 UHPC mixtures comprising cement, fine and coarse aggregates, silica fume, fly ash, water, superplasticizer, and steel fiber to develop reliable, data-driven compressive strength (CS) predictors with reduced environmental footprint. Six ensemble models— CatBoost, Extra Trees (ETR), XGBoost, Gradient Boosting (GB), Histogram Gradient Boosting (HistGB), and Random Forest (RF) were trained and evaluated using coefficient of correlation (R2), RMSE, MAE, and mean absolute percentage error (MAPE) on stratified train/test splits. Model behavior was further examined with Taylor diagrams and radar plots, while Shapley Additive Explanations (SHAP) and partial-dependence plots (PDPs) were used to interpret variable effects and interactions. CatBoost delivered the best overall performance, attaining the highest test R2 (0.863) and the lowest test RMSE. Extra Trees ranked second with competitive accuracy (test R2 = 0.854) and the lowest MAPE in training/testing. XGBoost was close behind (test R2 = 0.836), while GB, RF and HistGB showed comparatively larger errors. SHAP revealed superplasticizer and cement as the most influential features, followed by silica fume and coarse aggregate; fly ash and fine aggregate had smaller, context-dependent effects. This study highlights the potential of supervised ML-based prediction for sustainable manufacturing of concrete with optimized performance.

Resumo em Inglês:

ABSTRACT To systematically optimize the surface quality of prismatic parts fabricated via material extrusion, specifically fused deposition modeling (FDM) process, this study first conducted twelve sets of Plackett-Burman (PB) experiments. Measurements were performed on both the top and side surfaces of each specimen. Data analysis revealed that the side surfaces consistently exhibited superior straightness and lower roughness compared to the top surfaces, indicating greater potential for process enhancement. Consequently, the subsequent investigation focused on improving side surface quality. Analysis of the PB data identified three key process parameters that exerted the most significant influence on side surface accuracy: infill density (E), layer height (G), and extrusion width (H). Building on this, a Response Surface Methodology (RSM) model was developed for the side surface using a Box-Behnken Design (BBD). Grey Relational Analysis (GRA) was then employed to integrate the two competing objectives—minimizing straightness error and minimizing surface roughness (Ra)—into a single comprehensive performance metric known as the Grey Relational Grade (GRG). Solving the derived nonlinear regression model yielded the theoretically optimal parameter combination: 10% infill density, 0.08 mm layer height, and 0.6 mm extrusion width, corresponding to a predicted maximum GRG of 0.9056. Experimental validation confirmed that components manufactured with these optimal parameters achieved a side surface straightness error of 0.036 mm and an average surface roughness (Ra) of 2.1 μm. Compared to other parameter sets within the BBD design space that yielded comparable straightness, this optimal combination reduced surface roughness by approximately 10%, thereby robustly validating the predictive capability and effectiveness of the developed model. This study provides an experimental, data-driven rationale for selecting the side surface as the primary optimization target, elucidates the influence mechanisms of the critical process parameters, and proposes a coherent PB-BBD-GRA framework. This integrated methodology offers a systematic solution—encompassing initial factor screening, empirical modeling, and multi-objective decision-making—for the precision manufacturing of functional surfaces on FDM-fabricated prismatic components.

Resumo em Português:

RESUMO De maneira cada vez mais fundamental está a busca pela conservação do patrimônio cultural e histórico, procurando analisar e compreender os materiais e métodos utilizados durante o período de sua construção, para realizar um restauro mais harmônico e eficiente, com materiais semelhantes aos originais. Nesse contexto, este trabalho teve como objetivo caracterizar e estudar as argamassas de revestimento das ruínas da Igreja de Santa Rita de Cássia, em Pedro Velho/RN – Brasil. Para tal, foram realizadas visitas in loco para observações visuais e registros fotográficos das ruínas, bem como a coleta de amostras de argamassas de todas as paredes, para posterior caracterização físico-química por meio de análise visual, tátil e técnicas analíticas de FRX, DRX, teor de argamassa (aglomerante:agregado) por ataque ácido e análise granulométrica. A partir disso constatou-se que as argamassas analisadas são ricas em cal, com aglomerante de natureza calcítica e areia de origem silicosa, como agregado, apresentando relações de aglomerante:agregado diferentes em quase todas as argamassas, variando traços de 1:3 a 1:13, comprovando a sua produção sem qualquer controle tecnológico. Portanto, para o caso de possível futuro restauro, devem ser realizadas com argamassas de cal e areia com traços diferentes, compatíveis com o local de assentamento.

Resumo em Inglês:

ABSTRACT In an increasingly fundamental way is the search for the conservation of cultural and historical heritage, seeking to analyze and understand the materials and methods used during the period of its construction, to carry out a more harmonious and efficient restoration, with materials similar to the originals. In this context, this work aimed to characterize and study the mortar covering the ruins of the Church of Santa Rita de Cássia, in Pedro Velho/RN – Brazil. To this end, on-site visits were carried out for visual observations and photographic records of the ruins, as well as the collection of mortar samples from all walls, for subsequent physical-chemical characterization through visual, tactile analysis and XRF analytical techniques, DRX, mortar content (binder:aggregate) by acid attack and granulometric analysis. From this, it was found that the mortars analyzed are rich in lime, with a binder of a calcitic nature and sand of siliceous origin, as aggregate, presenting different binder:aggregate ratios in almost all mortars, ranging from 1:3 to 1:13, proving its production without any technological control. Therefore, in the case of possible future restoration, they must be carried out with mortars made of lime and sand with different traits, compatible with the installation location.

Resumo em Inglês:

VISUAL ABSTRACT

Resumo em Inglês:

ABSTRACT Steel–concrete hybrid composites reinforced with Carbon Fibre Reinforced Polymer (CFRP) are widely used for structural retrofitting and seismic strengthening due to their superior load-carrying capacity, stiffness, and durability. However, accurately modelling the nonlinear and time-dependent behaviour of these multi-material systems remains challenging because of the complex interaction between steel, concrete, and CFRP under varying loading conditions. This study proposes a machine-learning–based predictive framework, termed Hybrid Deep Regression Network with Physics-Informed Feature Embedding (HDRN–PIFE), to estimate the structural response of CFRP-wrapped steel–concrete hybrid members. The framework integrates a one-dimensional convolutional neural network (1D-CNN) for feature extraction with a bidirectional long short-term memory (Bi-LSTM) network for temporal sequence learning. Physics-informed descriptors, such as the confinement ratio and the stiffness degradation index, are embedded in the learning process to enhance interpretability and physical consistency. The model was trained and validated using an extensive experimental database comprising axial, flexural, and cyclic loading tests. Comparative analyses demonstrated that the proposed framework outperformed traditional finite element (FE) and empirical models. Prediction errors in axial load capacity were reduced by 35–48%, ductility prediction accuracy improved by 52%, and estimation of ultimate displacement and energy dissipation improved by 41%. Sensitivity analysis identified confinement effectiveness, CFRP stiffness, and steel yield strength as dominant parameters influencing structural performance. The results confirm that the HDRN–PIFE framework provides a reliable, data-driven tool for performance prediction and design optimization of CFRP-strengthened hybrid composite systems.

Resumo em Português:

RESUMO A madeira permanece como insumo relevante na construção civil devido à origem renovável, ao baixo consumo energético no processamento e ao potencial de estocagem de carbono. Mesmo com redução do seu uso, o material ainda exerce funções estruturais e não estruturais. A aplicação envolve benefícios ambientais e desempenho físico satisfatório, embora existam limitações relacionadas à propagação do fogo e propriedades físico-mecânicas dependentes da umidade. O conhecimento das propriedades da madeira é fundamental para explorar seu potencial em aplicações estruturais, energéticas e estéticas. A caracterização das madeiras auxilia na correlação entre suas propriedades químicas, térmicas e mecânicas, fornecendo subsídios para a definição de aplicações mais eficientes e seguras. O objetivo do trabalho é avaliar as propriedades químicas, térmicas e físico-mecânicas de três espécies de madeira, sendo elas garapeira (Apuleia leiocarpa), cumarú (Dipteryx odorata) e itaúba (Mezilaurus itauba) por ensaios de FTIR, TGA, teor de umidade, densidade aparente, compressão e tração paralelas às fibras. As análises identificaram grupos funcionais, etapas de degradação térmica e diferenças de resistência e estabilidade dimensional. O Cumarú apresentou resistência à tração em U12% de 96,24 MPa, seguido pela Itaúba com 88,13 MPa, enquanto a Garapeira apresentou menor resistência à compressão de 36,41 MPa, e as três espécies demonstraram comportamento térmico semelhante, concluindo-se que a densidade e a composição estrutural influenciam o desempenho mecânico. Dessa forma destaca-se a importância de aprofundar estudos com análises integradas, como FTIR e TGA, para ampliar a correlação entre estrutura química, estabilidade térmica e resistência mecânica das madeiras.

Resumo em Inglês:

ABSTRACT Wood remains a relevant input in civil construction due to its renewable origin, low energy consumption in processing, and carbon storage potential. Even with reduced use, the material still performs structural and non-structural functions. Its application involves environmental benefits and satisfactory physical performance, although limitations exist related to fire propagation and moisture-dependent physical-mechanical properties. Knowledge of wood properties is fundamental to exploring its potential in structural, energy, and aesthetic applications. Characterizing wood helps correlate its chemical, thermal, and mechanical properties, providing support for defining more efficient and safe applications. The objective of this work is to evaluate the chemical, thermal, and physical-mechanical properties of three wood species: garapeira (Apuleia leiocarpa), cumaru (Dipteryx odorata), and itauba (Mezilaurus itauba), using FTIR, TGA, moisture content, apparent density, compression, and tensile strength parallel to the fibers. The analyses identified functional groups, stages of thermal degradation, and differences in strength and dimensional stability. Cumaru showed a tensile strength in U12% of 96.24 MPa, followed by Itauba with 88.13 MPa, while Garapeira showed the lowest compressive strength of 36.41 MPa. All three species demonstrated similar thermal behavior, concluding that density and structural composition influence mechanical performance. This highlights the importance of further studies using integrated analyses, such as FTIR and TGA, to broaden the correlation between chemical structure, thermal stability, and mechanical strength of wood.

Resumo em Inglês:

ABSTRACT Developing environmentally benign volatile switches for high-density memory arrays requires eliminating toxic arsenic and selenium without compromising thermal or electrical reliability. This study implements an interpretable machine learning framework to guide the compositional optimization of ternary chalcogenide systems. By leveraging SHAP feature analysis, we identified that a specific atomic balance is required to optimize network connectivity while maintaining high polarizability. Experimental validation of the ML-designed candidates revealed that a symmetric modifier ratio of Si10Ge10Te80 yields the most robust amorphous network, achieving a crystallization temperature of 235 °C and an optical bandgap of 1.05 eV. Electrical characterization of crossbar devices utilizing this composition demonstrates excellent volatile switching behaviors, characterized by a sharp threshold voltage of 1.25 V and an extremely low off-state leakage current of 5.3 × 10-8 A. Furthermore, the optimized device exhibits superior dynamic performance, featuring a fast switching speed of approximately 12 ns and high endurance exceeding 108 cycles, significantly outperforming silicon-rich variants which failed near 105 cycles due to devitrification. The findings confirm that controlling the average valence electron concentration around 5.1 allows for the suppression of leakage pathways while ensuring sufficient thermal stability, proving that data-driven material selection can effectively engineer high-performance, eco-friendly components for next-generation storage class memory.

Resumo em Inglês:

ABSTRACT An experimental investigation was performed for improving impact toughness and tensile strength of AZ80A Mg alloy plates during FSW, by formulating empirical statistical models via response surface methodology. An inclusive multi–objective optimization strategy incorporating graphical and statistical techniques was also employed for determining important process parameters. A Central Composite Design consisting of 15 experimental runs was employed to systematically evaluate effects of traverse speed, shoulder diameter and rotational speed, on mechanical performance of joints. Experimental inferences revealed that tool’s traverse speed played a dominant role in impacting impact toughness and tensile strength, followed by tool’s shoulder diameter and rotational speed. Interaction amidst traverse and rotational speed had impacted tensile strength, whereas traverse speed and shoulder diameter’s interaction had played a vital role in ascertaining impact toughness. 1.246 mm/sec traverse speed, 12.868 mm shoulder diameter, 1021 rpm was identified as optimized parameters and flaw free joints fabricated at this combination exhibited 170.48 MPa tensile strength and 23.41 J impact toughness. Perfect accuracy of the formulated statistical model was confirmed by validation experimental results, exhibiting negligible discrepancy amidst anticipated and actual runs. SEM analysis of the fractured specimen of the flaw free joints exhibited a ductile failure, demonstrating superior plastic deformation capability.

Resumo em Inglês:

ABSTRACT To explore the effects of various factors on the recycling rate of reclaimed asphalt in reclaimed asphalt mixtures and optimize their production processes and mix design, the optimal type and content of rejuvenator through performance tests on the reclaimed asphalt were first determined. Subsequently, an evaluation method for measuring the recycling rate of reclaimed asphalt was proposed based on the performance indicators obtained from a dynamic shear rheometer (DSR). Finally, the effects of reclaimed asphalt content, heating temperature, and mixture mixing time on the recycling rate were analyzed using orthogonal experimental design. The results indicate that an appropriate rejuvenator content can effectively improve the performance of reclaimed asphalt, while excessive content adversely affects its high-temperature performance; consequently, the optimal content of Rejuvenator A is determined to be 10.1% for the evaluation of the recycling rate; the content of reclaimed asphalt has a significant inverse effect on the recycling rate, where a higher content leads to a lower rate; in addition, heating temperature is identified as the second most influential factor, with the recycling rate increasing progressively as the temperature rises. Furthermore, sufficient mixing time significantly enhances the recycling rate, whereas excessive mixing time reduces it.

Resumo em Inglês:

ABSTRACT Traditional Shanxi dwellings constructed with grey brick masonry and elm–pine timber frames represent a significant corpus of northern Chinese vernacular architecture, yet progressive material degradation threatens their structural integrity. This study develops and validates the Digital Heritage Characterization and Analysis Framework (DHCAF), an integrated workflow combining high-resolution terrestrial laser scanning, Structure-from-Motion photogrammetry, Infrared Thermography (IRT), and Material Microstructure Mapping (MMM) for non-invasive material diagnostics. Application to 36 georeferenced case-study houses (1680–1912 CE) enabled sub-centimeter geometric reconstruction (98.6%-dimensional accuracy; 7.2 mm MAE) and high-precision material segmentation (96.4% classification accuracy), representing measurable improvements over single-modality pipelines. Multi-modal analysis identified statistically significant correlations between façade orientation and moisture concentration (north-facing timber elements exhibiting 18–24% higher surface moisture indices) and between masonry composition and salt crystallization intensity, with lime-rich brick joints showing a 31% higher efflorescence incidence than stone assemblies. Spatially integrated BIM-linked datasets further quantified wall thickness variation (480 ± 95 mm) and timber cross-sectional dimensions (210 × 210 mm mean), enabling comparative structural assessment across typologies. The study demonstrates that DHCAF delivers reproducible, quantitatively validated material diagnostics and establishes a scalable digital methodology for evidence-based conservation planning of traditional masonry–timber heritage architecture.

Resumo em Inglês:

ABSTRACT The modernization of aging hydropower infrastructure is critical for enhancing energy efficiency and extending the operational lifespan of existing stations. Against this background, the objective of this study was to optimize the geometric design of the adjustable guide vanes in the retrofit scheme of Huilong Hydropower Station by employing computational fluid dynamics (CFD) analysis of the flow passage. The aim was to reduce flow resistance and energy loss, thereby improving the hydraulic efficiency and operational stability of the turbine unit. Based on rated operating conditions, CFD simulations were carried out to compare the flow fields of the original unit and the modified unit after runner replacement. The simulation results indicate that adopting the optimized guide vanes increases the hydraulic efficiency by 0.3% (from 92.2% to 92.5%) and the power output by 206 kW (from 38,660 kW to 38,866 kW). These quantitative comparisons verify that the retrofit exerts a positive but limited influence on performance, confirming that the original guide vane design remains highly compatible with the replaced runner. This study not only refines the retrofit scheme of Huilong Hydropower Station but also provides valuable theoretical guidance and engineering references for the upgrading and optimization of similar turbine units.

Resumo em Inglês:

ABSTRACT The primary treatment for cancer is chemotherapy; however, it causes side effects, which motivates research focused on the development of delivery systems for antineoplastic agents. One example is the hydroxyapatite (HAp) carrier, as it is a biocompatible and non-toxic biomaterial that can acquire antibacterial properties with the addition of zinc oxide (ZnO) nanoparticles, preventing possible infections during surgical procedures. Furthermore, functionalization with folic acid (FA) enables active targeting of tumor cells, while curcumin (Cur) exhibits antitumor activity. The objective of this study was to develop a carrier with antibacterial properties using FA-functionalized HAp@ZnO for curcumin delivery. HAp synthesized by the hydrothermal method was evaluated through in vitro bioactivity assays. Subsequently, ZnO nanoparticles were incorporated into HAp, and antibacterial activity was assessed against Staphylococcus aureus and Escherichia coli. The material was then functionalized with FA, curcumin was incorporated, and hemolysis and cytotoxicity assays were performed. Characterization techniques included Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, and Ultraviolet–Visible (UV–Vis) absorption spectroscopy. The synthesized HAp exhibited a crystalline, bioactive material with high surface area. HAp@ZnO showed well-defined inhibition halos for both bacteria, except for the HAp@20%ZnO sample against E. coli. The amount of curcumin adsorbed was 54.79 ± 3.52% for HAp@10%ZnO.AF.Cur and 45.49 ± 3.79% for HAp@20%ZnO.AF.Cur. HAp effectively modulated the toxicity of the active components, significantly reducing the hemolytic effects of ZnO and curcumin. The results indicate biocompatibility in non-tumor cells and suggested differential cytotoxic response in tumor cells. Therefore, a promising carrier for targeted antitumor therapy was developed, combining antibacterial activity, active targeting, controlled release, and biocompatibility.

Resumo em Inglês:

Abstract The study explores the possibilities of using calcinated waste coffee husk ash (WCA) as a natural alkaline activator in one-part geopolymer concrete. WCA was calcinated at 1000 °C for 2–14 hours at 2-hour intervals, and physicochemical characteristics were determined, including pH, water solubility, and Loss on Ignition (LOI). The effect of calcination period on the reactivity of WCA and its impact on the mechanical performance of geopolymer concrete was evaluated by replacing part of GGBS with WCA. These findings suggest that the 12-hour calcination of WCA shows better performance with a maximum pH (13.98), water solubility (54.5%), and calcination efficiency (LOI = 23.15%). Concrete mixes that used 15 percent replacement with 12-hour calcinated WCA (C12H15) noted the highest mechanical performance, which has 16 percent increased compressive strength at 28 days, relative to 10-hour calcinated WCA mixes. The optimized mixes were further proved to be superior in terms of fresh and mechanical performance, as confirmed by workability, compressive strength, and split tensile strength tests. The research confirms that properly calcinated WCA has the potential to replace traditional chemical activators, which would be a green, cost-effective, and environmentally friendly option in a massive building. This also solves the environmental issue of waste disposal of coffee husks, which would ensure sustainable construction without affecting the structural performance. Based on reported literature, one-part geopolymer systems can reduce carbon emissions by about 30–40% compared to conventional OPC concrete.

Resumo em Inglês:

ABSTRACT The escalating issue of nitrite (NO2−) contamination in aquatic environments necessitates the development of highly sensitive and selective detection methods. In this study, a series of porous Co3O4/N-doped carbon (Co3O4/NC) nanocomposites were successfully synthesized through a facile one-step pyrolysis of a zeolitic imidazolate framework-67 (ZIF-67) precursor at varying temperatures (500, 600, 700, and 800 °C). The effect of pyrolysis temperature on the physicochemical properties and electrochemical sensing performance of the resulting materials was systematically investigated. The optimized nanocomposite, Co3O4/NC-700, obtained at 700 °C, exhibited a well-defined porous dodecahedral morphology with uniformly dispersed Co3O4 nanoparticles embedded within a highly conductive N-doped carbon matrix. This unique architecture provided a large electroactive surface area, abundant active sites, and rapid electron transfer pathways. When employed as an electrode modifying material for electrochemical nitrite sensing, the Co3O4/NC-700 based sensor demonstrated outstanding performance, including a wide linear range from 0.1 µM to 1500 µM, a high sensitivity of 850.3 µA mM−1 cm−2, and an ultralow detection limit of 0.03 µM (S/N = 3). Furthermore, the sensor exhibited good repeatability (RSD = 2.8%, n = 7), electrode-to-electrode reproducibility (RSD = 3.9%, n = 5), and retained 94.5% of its initial response after 30 days. In tap water and river water, recoveries obtained by the standard addition method ranged from 98.6% to 103.2%, confirming the reliability of the proposed sensor for real-sample analysis. This work presents a simple and effective strategy for designing advanced MOF-derived nanocomposites for high-performance environmental monitoring applications.

Resumo em Inglês:

ABSTRACT The development of concrete with superior mechanical performance and enhanced durability remains a major challenge in structural engineering. This study proposes and experimentally validates a cross-scale enhancement strategy based on the combined action of hierarchical pore refinement and synergistic hydration, achieved through XYPEX crystalline admixture and nano-calcium carbonate (nano-CaCO3). By densifying pores from the nano- to micro-scale, the composite system significantly improves both mechanical properties and durability. With 1% XYPEX and 0.5% nano-CaCO3, the 28-day compressive strength reached 48.5 MPa, representing a 31.8% increase over the reference mix. A Synergistic Efficiency (SE) analysis confirmed that this enhancement exceeds the sum of the individual contributions (SE > 1.0). For durability, the mixture with 2% XYPEX and 1% nano-CaCO3 achieved the lowest water penetration depth of 17 mm, and the combination of 3% XYPEX and 1.5% nano-CaCO3 provided the best frost resistance, retaining 55.9% of relative dynamic elastic modulus after 100 freeze–thaw cycles. This enhancement is attributed to a physico-chemical synergy where nano-CaCO3 acts as a nucleation promoter accelerating hydration, while XYPEX consumes available Ca(OH)2 to form pore-blocking micro-crystals. This “cross-scale hierarchical collaboration” offers a promising paradigm for high-performance concrete design.

Resumo em Inglês:

ABSTRACT Industrial wastewater treatment systems often experience difficulties in regulating pH, as the neutralization process is highly nonlinear and time-varying. Conventional controllers such as PI and PID struggle to perform reliably under such variable conditions. To alleviate the limitations of overshoot, slow response, and instability of the response surface models, an ANFIS-based adaptive control strategy optimized using Chicken Swarm Optimization (CSO) is employed. The uniqueness of this study lies in the tuning of ANFIS parameters and fuzzy membership functions using CSO. This enables the adaptive controller to self-tune in response to process variations and disturbances in real time. The CSO-ANFIS hybrid approach combines neural network (NN) learning capability with fuzzy logic interpretability, which is further enhanced by CSO’s global search efficiency. The simulation results show that the proposed CSO-ANFIS controller reduces the percentage overshoot to 0.4712% compared with 4.9163% in the PI controller and achieves a faster settling time of 20.7680 s under disturbance conditions. These improvements demonstrate enhanced stability, tracking accuracy, and robustness for industrial wastewater pH control.

Resumo em Inglês:

ABSTRACT The complex demands on contemporary engineering components have led to the development of advanced materials, such as functionally graded materials. A functionally graded material, P91 and 304 stainless steels (SS), were developed by WAAM and afterwards, post-processing method of thermomechanical processing is adopted. The primary objective of this approach is to enhance interfacial bonding and microstructural control between distinct base metals. The thermomechanical processing encompassed isothermal compression testing at varying deformation temperatures (800, 900, and 1000°C) and strain rates (1 and 10 s–1). The corrosion performance of the as-built bimetallic component was compared with that of the base metals, P91 and 304 SS, by evaluating their electrochemical behaviour in a 3.5 wt% NaCl solution. Hardness results after deformation confirmed microstructural refinement, as evidenced by increasing hardness due to thermomechanical processing parameters. The corrosion results indicated that the thermomechanical processing parameters improved corrosion resistance due to the refined microstructure in the bimetallic component. Uniform corrosion dominated in the as-built condition of the bimetallic component, while pitting corrosion dominated under deformation conditions.

Resumo em Inglês:

ABSTRACT This study examines the effects of incorporating nano-silica (NS) and silica fume (SF) on the performance of lightweight concrete containing Lightweight Expanded Clay Aggregate (LECA) as a partial or full replacement for coarse aggregate. Concrete mixtures were designed with LECA replacement ratios of 25%, 50%, 75%, and 100%, along with 2% NS and 5% SF by weight of cement. The results demonstrated that increasing LECA content significantly reduced concrete density and compressive strength, with the latter decreasing by 50% at full replacement. However, the incorporation of NS and SF improved performance, increasing compressive strength by 22.9% at 50% LECA replacement and splitting tensile strength by up to 7.6%, while reducing water absorption by 19.5%, thereby enhancing concrete durability. Additionally, NS and SF contributed to better particle packing and microstructural densification, mitigating the negative effects of LECA’s high porosity. Despite the reduction in compressive strength, the study indicates that up to 75% LECA replacement, combined with NS and SF, produces lightweight concrete with mechanical properties suitable for structural applications, meeting the criteria of ACI 213R-87. These findings demonstrate that integrating LECA, NS, and SF offers a promising approach for developing lightweight concrete with enhanced durability and optimized mechanical properties.

Resumo em Inglês:

ABSTRACT This study evaluates the incorporation of ornamental stone processing waste into adhesive mortars as a partial substitute for natural fine aggregate. Mortar formulations were produced with 0%, 10%, 20%, and 30% replacement levels, using a standard 1:2 cement-to-aggregate mass ratio. Comprehensive fresh-state (air content, density, water retention, slip) and hardened-state (open time, tensile adhesion strength under varied curing regimes) characterizations were performed. Results showed significant reductions in entrained air and improved density with increasing waste content. A 30% replacement yielded the highest tensile adhesion strength (0.97 MPa) under normal curing, surpassing the 0.5 MPa thresholds defined by Brazilian standards for AC I and AC II mortars. The findings support the sustainable reuse of siliceous-rich residues, aligning material performance with environmental benefits. This work contributes to the circular economy and enhances structure-property correlations in eco-efficient cementitious systems.

Resumo em Inglês:

ABSTRACT Dry sliding in precision finishing generates frictional heat that degrades surface integrity and dimensional stability. TiN coatings are used to suppress adhesion and ploughing in steel contacts, yet comparison of their thermal endurance with uncoated steels remains limited. Quantitative links among frictional energy, wear rate, and threshold-based thermal endurance across coated and uncoated steels under identical conditions remained incomplete. This study evaluates energy dissipation, wear rate, and thermal-threshold endurance for TiN-coated steel relative to hardened steel and AISI 304 stainless steel under dry sliding. Alumina ball-on-disk tests were conducted at 5–15 N and 0.2–0.8 m s−1 over 100 m. Friction, temperature, and wear volume were measured, and response surface methodology was used for optimisation. At 10 N and 0.5 m s−1, friction coefficients of 0.66, 0.58, and 0.49 and specific wear rates of 2.70 × 10−4, 1.10 × 10−4, and 0.30 × 10−4 mm3(N·m)−1 were obtained for stainless steel, hardened steel, and TiN-coated steel. Peak temperatures of 78, 62, and 49 °C were recorded, and TiN-coated steel remained below 70 °C for 100 m across the matrix, which establishes thermal endurance. This work defines a low-damage operating window for coolant-limited finishing, and future work should extend the framework to sustainable and elevated sliding speeds.

Resumo em Inglês:

ABSTRACT The production of ordinary Portland cement (OPC) is a major contributor to global CO2 emissions, prompting the development of geopolymer concrete as a sustainable alternative. However, the dependence of geopolymer technology on commercially produced sodium silicate poses environmental and economic challenges due to its energy-intensive manufacturing process. This study investigates the synthesis of sodium silicate from agro-waste ashes, rice husk ash (RHA), sugarcane bagasse ash (SCBA), and palm oil fuel ash (POFA), and evaluates their effectiveness as alkaline activators in geopolymer concrete. Mixes were prepared with activator molarities ranging from 6M to 18M and assessed for fresh, mechanical, and durability properties. The results revealed that performance improved with increasing molarity up to 13M, beyond which strength and workability declined due to excess alkalinity, causing microcracking. RHA-based sodium silicate demonstrated the highest compressive strength (45 MPa), comparable to the control mix using commercial sodium silicate, followed by SCBA (43 MPa) and POFA (41.5 MPa). Durability assessments indicated superior acid resistance and lower water absorption in RHA- and SCBA-based mixes. The findings confirm that agro-waste-derived sodium silicate can effectively replace conventional activators, promoting sustainable geopolymer concrete production and significantly reducing environmental impacts.

Resumo em Inglês:

ABSTRACT This study evaluates the influence of polyvinyl alcohol (PVA) fibers on the mechanical behavior and high-temperature performance of concrete beams reinforced with glass fiber-reinforced polymer (GFRP) bars. The experimental variables included fiber addition levels (0.00%, 0.10% and 0.15% by volume) and exposure to thermal cycling at 300°C, 500°C, or no heating. For unheated specimens, fiber addition reduced void ratio, water absorption, bulk density, ultrasonic pulse velocity, dynamic modulus of elasticity, and compressive strength, while enhancing flexural strength with increasing fiber content. For beams exposed to thermal cycling, the 0.10% fiber content showed least loss in flexural strength after heating, with an increase of 2.72% and a decrease of 15.68% in strength at 300 °C and 500 °C, respectively. Exposure to 500 °C significantly reduced flexural strength for all mixtures, with a maximum reduction of 41.71% for the 0.15% fiber content. Nevertheless, fiber-reinforced beams consistently exhibited higher ultimate loads than reference beams. No clear improvement in ductility was observed at elevated temperatures. Engineering analysis demonstrates that fiber effectiveness is non-linear, with 0.10% identified as optimal content for maximizing thermal-mechanical performance. These findings highlight importance of dosage control in GFRP-reinforced beams as a practical strategy to enhance structural resilience and safety under high-temperature conditions.

Resumo em Inglês:

ABSTRACT The environmental impact of water contamination has driven the search for sustainable materials for wastewater treatment, especially in the textile industry. The production of carbonaceous materials from biomass stands out as a low-cost and accessible alternative, promoting sustainable development and environmental preservation. This study aimed to produce biochar from leucaena (Leucaena leucocephala) pods and seeds impregnated with Black Liquor and evaluate its performance in removing methylene blue as a model cationic dye. The materials (original and carbonized) were characterized using several techniques, including thermogravimetry, infrared spectroscopy, X-ray diffraction, scanning electron microscopy, ammonia desorption, specific surface area analysis, point of zero charge determination, and Raman spectroscopy, and tested as adsorbents for methylene blue removal. The original materials exhibited a residual mass of 25–54% after pyrolysis up to 600 °C and maintained thermal stability in the range of 400 and 1000 °C. Regarding the total acidity, the results of ammonia desorption at programmed temperature showed that the samples obtained from the leucaena and liquor mixture exhibited higher acidity. The leucaena-black liquor mixture materials efficiently removed methylene blue at alkaline pH (>7.0–9.0), achieving removal efficiencies of 94.08% (pod) and 87.17% (seed). The adsorption kinetics followed a pseudo-second order model, with adsorption capacities of 3.64 mg.g–1 (seed-liquor) and 4.40 mg·g–1 (pod-liquor).

Resumo em Português:

RESUMO Este trabalho avaliou o desempenho elétrico de uma Stack Fuel Cell PEM, alimentada por hidrogênio, utilizada como gerador para cargas em sistemas isolados. A análise foi realizada por meio do acoplamento direto da Stack à conexão de entrada de painéis fotovoltaicos de um inversor solar híbrido comercial, verificando sua viabilidade como fonte auxiliar. Foi realizada a caracterização da Stack em corrente contínua (CC) e alternada (CA) alimentando uma carga resistiva de 5 kW via inversor. Em CA, examinou-se o desempenho do sistema com foco na resposta do rastreamento do ponto de máxima potência (MPPT) frente à alimentação proveniente da célula a combustível, bem como na atuação de um sistema de armazenamento por baterias também conectado ao inversor, utilizado para suporte e estabilização da energia pelo gerador principal. O sistema mostrou capacidade de alimentar cargas, mas o MPPT, otimizado para fontes fotovoltaicas, limitou a potência extraída da célula exigindo suporte do banco de baterias sob cargas elevadas. Apesar disso, as curvas de polarização em CA e CC foram similares, indicando que a Stack manteve desempenho adequado sob modulações lentas. Concluiu-se que o acoplamento direto é viável, porém há necessidade de inversores otimizados para células a combustível.

Resumo em Inglês:

ABSTRACT This study evaluated the electrical performance of a PEM Fuel Cell Stack, powered by hydrogen, used as generator for loads in isolated systems. The analysis was conducted through the direct coupling of the Stack to the input connection of photovoltaic panels in a commercial hybrid solar inverter, assessing its feasibility as auxiliary power source. The Stack was characterized under both direct (DC) and alternating (AC) current conditions while supplying a 5 kW resistive load via the inverter. In AC mode, the system’s performance was examined with a focus on the response of the maximum power point tracking (MPPT) system when powered by the fuel cell, as well as the operation of a battery storage system also connected to the inverter, used for support and stabilization of energy delivery by the main generator. The system demonstrated the capability to supply loads, but the MPPT—optimized for photovoltaic sources—limited the power extracted from the fuel cell, requiring support from the battery bank under high-load conditions. Nevertheless, the polarization curves under both AC and DC were similar, indicating that the Stack maintained adequate performance under slow modulations. It was concluded that direct coupling is feasible; however, inverters optimized for fuel cells are necessary.

Resumo em Português:

RESUMO Este estudo caracterizou a linha adesiva e a penetração do adesivo em vigas de madeira lamelada colada (MLC) de Lyptus não tratado coladas com poliuretano monocomponente Jowapur 686.60. As vigas foram fabricadas conforme o fabricante; de cada viga, duas lâminas foram seccionadas e preparadas em corpos de prova específicos para microscopia óptica com luz polarizada (MOLP), microscopia óptica de fluorescência (MOF), microscopia confocal de fluorescência (MCF), microscopia eletrônica de varredura (MEV) e microtomografia de raios X (micro-CT). Após a cura, observaram-se bolhas de ar na linha de cola, cristais e indícios de tensões residuais, possivelmente associados ao desempenho em cisalhamento. A penetração ocorreu em vasos, lúmens de traqueídes e ao longo dos raios, com distribuição influenciada pela densidade da madeira. As técnicas foram complementares: a MOLP evidenciou tensões, cristais e bolhas; a MOF distinguiu fases, porém com menor resolução e necessidade de sonda; a MCF forneceu alta resolução, com sombras em regiões irregulares; a MEV permitiu medir a espessura da linha de cola; e a micro-CT viabilizou análise 3D, indicando a necessidade de contraste em madeiras densas. Conclui-se que a combinação de técnicas é crítica para avaliar a qualidade das ligações adesivas em MLC.

Resumo em Inglês:

ABSTRACT This study characterized the bondline and adhesive penetration in glued laminated timber (glulam) beams manufactured with untreated Lyptus® wood and the one-component polyurethane adhesive Jowapur® 686.60. The beams were produced according to the manufacturer’s specifications; from each beam, two lamellae were sectioned and prepared into specimens tailored to polarized light optical microscopy (PLOM), fluorescence optical microscopy (FOM), confocal fluorescence microscopy (CFM), scanning electron microscopy (SEM), and X-ray microtomography (micro-CT). After curing, air bubbles were observed in the bondline, along with crystals and evidence of residual stresses, which may be related to shear performance. Adhesive penetration occurred in vessels, tracheid lumina, and along rays, with its distribution influenced by wood density. The techniques proved complementary: PLOM highlighted residual stresses, crystals, and bubbles; FOM enabled phase identification but had lower resolution and required a fluorescent probe; CFM provided high-resolution imaging but showed shadowing in irregular regions; SEM was effective for measuring bondline thickness; and micro-CT enabled three-dimensional assessment of penetration, indicating the need for contrast in dense woods. The study underscores the importance of combining these techniques to assess bonding quality in glulam.

Resumo em Inglês:

ABSTRACT Due to the increasing demand for ready-made clothing, wastewater treatment facilities are producing large amounts of textile effluent sludge (TES), which is often dumped as backfill and contributes to groundwater and land contamination. Compressive strength (CS), a vital property of concrete, is usually measured through experimental tests that are both costly and time-consuming. To promote eco-friendly construction, this study investigates the mechanical, microstructural, environmental, and machine learning (ML) characteristics of concrete containing various TES percentages. The significance of this research lies in integrating TES as a partial cement and aggregate replacement with ML-based compressive strength prediction, providing a rapid cost cost-effective alternative to traditional experimental testing. Random forest (RF), linear regression (LR), extreme gradient boosting (XGB), and support vector regression (SVR) models were developed using 253 datasets from previous studies, with the RF model achieving superior performance with R² values of 0.927 for training and 0.915 for testing. Analysis revealed that 15% TES replacement reduced compressive strength by 25.21% after 28 days while decreasing the environmental footprint by 13.90%, indicating an optimal balance between sustainability and performance. SEM observations confirmed increased porosity and ettringite formation in TES-modified concrete, correlating with the slight reduction in strength. Overall, this study presents an innovative, eco-friendly concrete solution that transforms hazardous TES into a valuable construction material while enabling reliable ML-based property prediction.

Resumo em Inglês:

ABSTRACT This study investigates the synergistic effect of magnesium hydroxide (MH) and calcium hydroxide (CH) nanoparticles on the mechanical, thermal, and flame-retardant performance of polyester / flax composites. Composites with 45 wt.% flax fabric and varying nanoparticle loadings (1–3 wt.%) were fabricated using the hand lay-up method. FTIR (Fourier transform infrared) spectroscopy confirmed strong chemical interactions between the nanoparticles and the polyester matrix, while SEM (Scanning electron microscope) revealed uniform nanoparticle dispersion and improved interfacial bonding. The optimized 2 wt.% hybrid composite exhibited notable improvements, including 37.7% higher tensile strength, over 320 % increase in flexural strength, enhanced impact resistance, and superior thermal stability with a 4.3 % rise in onset degradation temperature. Flame-retardant tests demonstrated significant improvements, with composites achieving LOI (Limited Oxygen Index) values above 24.4%, UL-94 V-0 rating, and HB classification, indicating excellent self-extinguishing behavior and reduced burning rates (<45 mm/min). The combined action of MH and CH nanoparticles promoted char formation, reduced heat release, and improved ignition resistance, surpassing the performance of single-filler systems. These results highlight the potential of dual nanoparticle reinforcement for developing lightweight, sustainable composites with balanced mechanical, thermal, and fire - safe properties, suitable for safety-critical applications in automotive, aerospace, and construction sectors.

Resumo em Inglês:

ABSTRACT Recent global assessments indicate that more than 80% of wastewater is discharged untreated, contributing significantly to environmental pollution and ecosystem degradation. In this study, an eco-friendly approach was employed to synthesise silver nanoparticles (AgNPs) using plant extracts as natural reducing and stabilising agents. The synthesised nanoparticles were immobilised onto suitable support matrices to develop reusable nanocatalysts for wastewater treatment. The developed nanocatalyst exhibited high catalytic efficiency, achieving >92% degradation of methylene blue within 45 min, following pseudo-first-order kinetics (k = 0.064 min−1). Comparable degradation performance was observed for phenol and Cr(VI), confirming the applicability to multiple pollutants. The catalyst demonstrated excellent stability, retaining 83% efficiency after 10 cycles, indicating strong structural integrity and reusability. The characterization using UV–Vis, FTIR, XRD, SEM/TEM, and TGA verified the creation of stable, crystalline, and evenly dispersed nanoparticles averaging 20 nm in size. Environmental assessment indicated negligible toxicity and minimal Ag+ leaching (<3%), attributed to phytochemical capping. These findings demonstrate that plant-derived AgNP-based nanocatalysts offer a sustainable, cost-effective, and scalable solution for wastewater remediation, aligning with green chemistry and circular economy principles.

Resumo em Português:

RESUMO A crescente demanda por eficiência energética na construção civil tem motivado o desenvolvimento de argamassas leves para revestimentos em envoltórias de edificações, produzidas com agregados porosos ou incorporadores de ar, como a hidroxipropilmetilcelulose (HPMC). Este estudo avalia, em condições laboratoriais controladas, o efeito da substituição parcial da areia natural por pó de poliestireno expandido (EPS), associada à adição de HPMC, sobre o desempenho mecânico e térmico de argamassas leves. Adotou-se uma argamassa de referência 1:3 (cimento:areia, em volume), sendo a areia substituída por EPS nos teores de 10%, 20%, 30%, 40% e 50%, com adição de 0,2% de HPMC em relação à massa de cimento. Os resultados são apresentados de forma comparativa em relação à argamassa de referência e indicam que a formulação com 50% de EPS e HPMC, observaram-se reduções de 64,4% na resistência à compressão, de 62,22% na absorção de água por capilaridade e de 48,43% na condutividade térmica, bem como aumento de 81,82% na resistência de aderência à tração e de 113,35% no índice de isolamento térmico. Os resultados indicam ganhos no desempenho térmico e na aderência, acompanhados de expressiva redução da resistência à compressão, caracterizando um trade-off entre propriedades mecânicas e térmicas nas condições experimentais estudadas.

Resumo em Inglês:

ABSTRACT The growing demand for energy efficiency in the construction sector has motivated the development of lightweight mortars for building envelope coatings, produced with porous aggregates or air-entraining agents, such as hydroxypropyl methylcellulose (HPMC). This study evaluates, under controlled laboratory conditions, the effect of partially replacing natural sand with expanded polystyrene (EPS) powder, combined with the addition of HPMC, on the mechanical and thermal performance of lightweight mortars. A reference mortar with a 1:3 mix proportion (cement:sand, by volume) was adopted, in which sand was replaced with EPS at levels of 10%, 20%, 30%, 40% and 5%, and 0.2% HPMC was added relative to the cement mass. The results are presented in comparison with the reference mortar and indicate that, for the mixture containing 50% EPS and HPMC, reductions of 64.41% in compressive strength, 62.22% in capillary water absorption and 48.43% in thermal conductivity were observed, as well as increases of 81.82% in tensile bond strength and 113.35% in the thermal insulation index. The results indicate improvements in thermal performance and adhesion, accompanied by a marked reduction in compressive strength, characterizing a trade-off between mechanical and thermal properties under the experimental conditions investigated.

Resumo em Inglês:

ABSTRACT The use of natural aggregates, particularly natural fine aggregate (NFA), in construction has been extensively studied; however, there remains a need for accurate and comprehensive characterization to understand the limits of their use in engineering materials fully. Our study examined numerous natural fine aggregate sites in desert areas and their use in concrete. The problem lies in identifying the types and varieties of fine aggregate over an area of more than 800 kilometers. The goal is to identify them by their physical, chemical, and mechanical properties. Based on extensive testing, the results showed that all of the natural aggregates studied were classified as very fine and clean aggregates. Chemical results then showed that these fine aggregates (FA) have a siliceous composition. The silica content reaches 98%. This confirms its potential for use as a construction aggregate. In addition, the grain distribution is asymmetrical, using the “fractal dimension” property. This encourages us to study this fine aggregate closely for use in concrete mixes and to work on using other types to correct it in terms of coarse grains. The preliminary results of natural fine aggregate (NFA) corrected with crushed fine aggregate (CFA) are very acceptable compared to using crushed fine aggregate alone.

Resumo em Português:

RESUMO A indústria da construção civil consome percentual considerável de recursos naturais para atender o crescimento populacional. Por outro lado, a extração de recursos naturais para agregar ao setor da construção civil gera impactos ambientais seja na emissão de CO2 ou na geração de resíduos sólidos. Para viabilizar a construção civil, a utilização do concreto armado se faz necessária na maioria dos casos. As operações da construção civil e principalmente a produção do concreto e do aço, demandam de setores que extraem uma quantidade substancial de materiais inertes para a produção do concreto e do aço. Diante dessas questões ambientais, buscando minimizar a extração de recursos naturais e dar destino a um resíduo de mineração, este estudo propõe analisar o desempenho no estado fresco e endurecido de concretos que incorporam agregados miúdos residuais provenientes da atividade de mineração. Com base nas curvas de distribuição granulométrica resultantes da combinação de agregados naturais e residuais, foram elaboradas diferentes misturas de concreto com diferentes teores de incorporação de agregado miúdo residual em substituição do agregado miúdo natural. Após a determinação das dosagens, foram realizados ensaios de densidade e abatimento de tronco de cone para avaliar a trabalhabilidade das misturas de concreto em estado fresco e a moldagem de corpos de prova para análise subsequente da resistência à compressão aos 7 e 28 dias de cura, absorção de água por imersão, microscopia eletrônica de varredura e câmara de envelhecimento. Ao final do estudo, constatou-se a possibilidade de utilização do agregado miúdo residual em razão dos resultados obtidos para as composições onde a incorporação de 30% de agregado miúdo residual atingiu resultados próximos aos resultados do material referência, produzido sem a incorporação de agregado miúdo residual.

Resumo em Inglês:

ABSTRACT The construction industry consumes a considerable percentage of natural resources to meet population growth. On the other hand, the extraction of natural resources for the construction sector generates environmental impacts, whether through CO2 emissions or solid waste generation. To make civil construction viable, the use of reinforced concrete is necessary in most cases. Civil construction operations, and especially concrete and steel production, require sectors that extract a substantial amount of inert materials for concrete and steel production. Given these environmental issues, seeking to minimize the extraction of natural resources and dispose of mining waste, this study aims to analyze the performance, in fresh and hardened states, of concrete incorporating residual fine aggregates from mining activities. Based on the particle size distribution curves resulting from the combination of natural and residual aggregates, different concrete mixes were developed with varying levels of residual fine aggregate incorporation to replace natural fine aggregate. After determining the dosages, density and slump tests were performed to evaluate the workability of the fresh concrete mixes. Specimens were molded for subsequent analysis of compressive strength at 7 and 28 days of curing, water absorption by immersion, scanning electron microscopy, and aging chamber. At the end of the study, the possibility of using residual fine aggregate was confirmed due to the results obtained for the compositions where the incorporation of 30% residual fine aggregate achieved results close to those of the reference material produced without the incorporation of residual fine aggregate.

Resumo em Português:

RESUMO O crescente interesse por materiais sustentáveis tem impulsionado pesquisas em compósitos poliméricos reforçados com fibras naturais, que surgem como alternativas ecológicas aos compósitos convencionais. Entre esses materiais, destaca-se o aproveitamento de resíduos lignocelulósicos, como o endocarpo do Cocos nucifera Linn. (coco seco), abundante no Brasil e ainda pouco explorado tecnologicamente. As fibras naturais apresentam diversas vantagens em relação às sintéticas, como renovabilidade, biodegradabilidade, menor abrasividade e baixo consumo energético durante sua produção, características que favorecem sua aplicação em setores como construção civil, indústria automotiva e fabricação de embalagens. Embora o uso de fibras de coco em matrizes poliméricas já tenha sido investigado com resultados promissores, o endocarpo permanece como uma fração do fruto subaproveitada, apesar de seu elevado potencial. Nesse contexto, o presente trabalho propõe a fabricação e caracterização de um compósito sustentável utilizando o endocarpo do coco, na faixa granulométrica de 0,212 mm a 0,5 mm, como material de reforço em uma matriz de poliamida 6 (PA6). Inicialmente, os materiais foram submetidos à secagem em estufa de ar circulante (60°C) e em estufa a vácuo (80°C) para eliminar a umidade. Posteriormente, utilizou-se a técnica de extrusão em uma extrusora dupla-rosca co-rotacional e, na sequência, o processo de injeção a 230°C. Essa temperatura, superior à de transição vítrea da lignina, foi escolhida para que o polímero natural auxiliasse na adesão do particulado à matriz, reduzindo problemas de interface. Para a caracterização do material compósito (10 wt.% e 20 wt.%), realizaram-se ensaios de densidade, absorção de água, tração e flexão, além de microscopia eletrônica de varredura (MEV) para a análise da fratura. A partir dos resultados, observou-se uma redução na resistência à tração dos compósitos quando comparados à PA6 pura; contudo, houve um aumento na resistência à flexão e no módulo de elasticidade. Na análise por MEV, constatou-se maior presença de vazios na amostra de 10 wt.% em relação à de 20 wt.%. Essa proposta visa agregar valor a resíduos agrícolas, reduzir a dependência de termoplásticos convencionais de longa degradação e estimular o desenvolvimento de materiais com menor impacto ambiental, contribuindo para a inclusão socioeconômica ao promover inovação tecnológica associada à sustentabilidade.

Resumo em Inglês:

ABSTRACT The growing interest in sustainable materials has driven research into natural fiber-reinforced polymer composites, which emerge as ecological alternatives to conventional composites. Among these materials, the utilization of lignocellulosic residues stands out, such as the endocarp of Cocos nucifera Linn. (dry coconut), which is abundant in Brazil and remains technologically under-explored. Natural fibers offer several advantages over synthetic ones, such as renewability, biodegradability, lower abrasiveness, and low energy consumption during production, characteristics that favor their application in sectors such as civil construction, the automotive industry, and packaging manufacturing. Although the use of coconut fibers in polymer matrices has been investigated with promising results, the endocarp remains an underutilized fraction of the fruit, despite its high potential. In this context, the present study proposes the fabrication and characterization of a sustainable composite using coconut endocarp, in the particle size range of 0.212 mm to 0.5 mm, as a reinforcing material in a polyamide 6 (PA6) matrix. Initially, the materials were dried in a circulating air oven (60°C) and a vacuum oven (80°C) to eliminate moisture. Subsequently, a co-rotating twin-screw extruder was employed, followed by an injection molding process at 230°C. This temperature, which is above the glass transition temperature of lignin (the endocarp’s natural resin), was selected to allow the natural polymer to assist in the adhesion of the particulates to the matrix, thereby reducing interface problems. To characterize the composite materials (10 wt.% and 20 wt.%), density, water absorption, tensile, and flexural tests were performed, along with scanning electron microscopy (SEM) for fracture analysis. The results indicated a reduction in the tensile strength of the composites compared to pure polyamide 6; however, there was an increase in flexural strength and modulus of elasticity. SEM analysis revealed a higher presence of voids in the 10 wt.% sample compared to the 20 wt.% sample. This proposal aims to add value to agricultural residues, reduce dependence on conventional thermoplastics with long environmental degradation periods, and stimulate the development of materials with lower environmental impact, contributing to socioeconomic inclusion by promoting technological innovation associated with sustainability.

Resumo em Inglês:

ABSTRACT The present work examines the synergistic action of Graphene Oxide (GO) and Nano-Silica (NS) in cementitious composites to study the influence of these nanocomposites on mechanical and durability performance. NS was added to concrete mixes to ensure a range of proportions was mixed uniformly (0.5%, 1.0%, and 1.5% by weight of cement). A range of GO proportions was also tested (0.03%, 0.06%, and 0.09%). Extensive testing, including compressive strength, split tensile strength, water absorption, and rapid chloride penetration tests, was conducted at the beginning of 7, 28, and 90 days of curing. Examination of results indicated that the best NS 1.0NS-GO 0.06GO blend enhanced compressive strength and lowered permeability of the chloride ion by 21.3% and 38.7%, respectively, when compared with control specimens. The advancement is attributed to increased matrix density, the effects of the fillers, and interfacial bonding initiated by the nanocomposites. SEM and FTIR studies supported improved microstructural integrity and hydration kinetics.

Resumo em Inglês:

ABSTRACT Natural fiber–reinforced composites are gaining increasing attention as sustainable alternatives to synthetic fiber composites due to their biodegradability, low density, and environmental compatibility. In this study, hybrid biocomposites reinforced with Ipomoea carnea fiber (ICF) and Tecoma stans fiber (TSF) were fabricated using a bio-phenolic resin (BPR) matrix through hand lay-up followed by compression molding. The structural, mechanical, thermal, and environmental performances of the composites were evaluated using FTIR, XRD, TGA, DMA, SEM, and GC–MS analyses. Five composite formulations were prepared with varying fiber ratios, and their properties were compared with neat BPR. Among them, the hybrid composite S4 (30 wt% ICF, 10 wt% TSF, 60 wt% BPR) exhibited superior overall performance, achieving a TS of 50.64 MPa, FS of 55.06 MPa, storage modulus of 3000 MPa, and thermal stability up to 470.6 °C. Impact strength improved significantly compared with the neat BPR matrix, indicating enhanced energy absorption due to improved fiber–matrix interfacial bonding. SEM analysis confirmed reduced voids and effective stress transfer in the hybrid composites. The optimized S4 composite also demonstrated moderate biodegradability (9.65% weight loss after 60 days) and controlled water absorption (3.95% after 168 h). GC–MS analysis revealed the presence of non-toxic bio-based compounds, indicating potential suitability for eco-friendly packaging applications.

Resumo em Inglês:

ABSTRACT The infrastructure layers of the highways must meet expectations both technically and economically. These layers that are not constructed properly cause deformations on the road surface. Steel slag should be preferred to reduce these deformations, increase the use of recycled materials worldwide, and create a sustainable system. For this purpose, the vertical deformation response of the flexible superstructure utilizing steel slag under dynamic wheel loads was analyzed numerically using the 3D FEM approach, in this study. Axle loads were applied considering the heavy vehicle tire layout plan and subjected to cyclic loading. The effect on the vertical settlement of the road was evaluated for four different sections defined using steel slag in the base and subbase layers. The axle load was applied to the determined wheel loading areas in loading steps throughout the cycle time, which was determined depending on the speed of the heavy vehicle and the tire dimensions. According to the results of the numerical analysis, the engineering performance of the sections with steel slag was better. Thus, innovative and sustainable approaches such as using steel slag aggregates instead of natural aggregates in the base and subbase layers of the highway were proposed.

Resumo em Inglês:

ABSTRACT Cold forward microextrusion is highly sensitive to frictional effects due to the large surface-to-volume ratio involved at the microscale, making lubrication a critical factor in process performance. This study investigates the influence of different lubricants on extrusion force, tribological response, material flow, and strain-hardening behaviour during cold forward microextrusion of Al6063 aluminium alloy. A segmented die microextrusion setup was employed to evaluate three lubricants—Servo 68 mineral oil, castor oil, and groundnut oil—along with dry conditions. Tribological performance was assessed indirectly through extrusion force–displacement behaviour, micro-pin length, and microhardness measurements. The results show that Servo 68 oil provides the most effective lubrication, achieving a 23.1% reduction in extrusion force compared with dry conditions and producing the longest micro-pins (average length ≈ 6.5 mm). Groundnut oil exhibited moderate performance, while castor oil showed comparatively lower lubrication efficiency. Microhardness increased significantly under lubricated conditions, reaching a maximum value of 59.86 HV with Servo 68 oil due to uniform strain hardening. The study establishes a direct correlation between lubrication efficiency, friction reduction, and mechanical strengthening in microscale extrusion. The findings are relevant to precision manufacturing of micro-pins, electrical connectors, electronic components, and other miniature mechanical assemblies.

Resumo em Inglês:

ABSTRACT The manufacturing sector is increasingly focusing on Fused Deposition Modeling (FDM) methods. However, existing parameter optimization for thermoplastic polyurethane (TPU) in FDM lacks systematic screening, quantitative interaction analysis, and rigorous stability verification. To address these deficiencies, this study proposes a systematic optimization method addressing these three core gaps. It investigates the effects of four FDM parameters—printing speed (A), printing temperature (B), infill rate (C), and layer height (D)—on TPU flexibility, which is characterized by elastic modulus , where lower values indicate superior fexibility. The methodologies employed include single-factor ANOVA, Duncan’s test, SPSS-analyzed orthogonal experiments, and verification tests. All parameters significantly affect the elastic modulus (p < 0.01), with the significance order of B > A > A × B (p < 0.05). The optimal parameters identified are 55 mm/s printing speed and 200 ℃ printing temperature, with a coefficient of variation of 0.40% (indicating stable performance). This study provides support for TPU flexibility optimization and FDM forming stability enhancement.

Resumo em Inglês:

ABSTRACT This research investigates the flexural behaviour of Reinforced Concrete (RC) beams that utilize diatomaceous earth powder as a partial substitute for cement, along with the addition of E-waste. Four beam specimens with consistent dimensions (150 mm × 180 mm × 1500 mm) were designed according to IS 456:2000 and subjected to testing under a 50-ton loading frame. The experimental findings indicated that the fibre-reinforced beams showed improved load-carrying capacity, ductility, and energy absorption when compared to the control beam. Among the fibre-reinforced specimens, RCC-FL30-F0.8-D20 exhibited the highest ultimate load capacity and energy absorption, suggesting an optimal balance in fibre dosage. Analysis of the failure modes revealed that the control beam failed due to compression crushing. In contrast, the fibre-reinforced beams experienced a combination of flexural and shear failures, with an excessive addition of E-waste fibre leading to a predominant shift in the failure mode towards shear. Evaluations of stiffness and ductility confirmed that moderate incorporation of fibres enhanced deformation capacity without sacrificing rigidity. A comparison between experimental results and analytical studies using finite element modelling showed excellent correlation, with mean ratios close to unity and minimal standard deviation, thereby validating the reliability of the numerical model. In summary, the results emphasise that the controlled addition of E-waste fibres and diatomaceous earth can significantly enhance the flexural performance and sustainability of RC beams. At the same time, finite element modelling serves as a dependable predictive tool for assessing structural behaviour.

Resumo em Inglês:

ABSTRACT Greenhouse gases, namely carbon dioxide emissions, cause variations in global temperature and relative humidity (RH), which some projections show that there will be a reduction in RH in certain areas as CO2 level increases. These fluctuations in CO2, temperature and RH significantly impact on carbonation depth in current systems. However, models for forecasting carbonation depth as a function of time in concrete components are limited to the extent of implementing important factors associated with the effects of climate change. Various concrete mixes containing 10 to 30% fly ash (FA), 3% nano silica particles (NSP) with a constant water to cement (w/c) ratio of 0.34 were used to test the durability and mechanical characteristics of nano fly ash concrete (NFC). After exposing these specimens for up to 28 days, the depth of carbonation (2% (vol.) CO2, 20°C, 65% RH) were investigated. Carbonation results show that NSP incorporated concrete mixes reduce carbonation depth by approximately 73% when compared to the control specimens.

Resumo em Inglês:

ABSTRACT Reliable monitoring of ground-level ozone is critical due to its severe impact on human health and ecosystems. This work presents a systematic investigation into the synthesis of nitrogen-doped graphene/TiO₂ (NGT) nanocomposites via a one-step hydrothermal strategy, specifically tailored for ultra-sensitive ozone detection. Advanced characterization techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), confirmed the successful anchoring of anatase TiO₂ nanoparticles (~13 nm) onto nitrogen-doped reduced graphene oxide sheets, resulting in a hierarchical porous structure with a significantly increased specific surface area of 165.3 m²/g. Gas sensing experiments revealed that the optimal NGT-3 composite delivers exceptional performance, exhibiting a high response of 25.8 toward 100 ppb ozone at a relatively low operating temperature of 100 °C. This represents a twelve-fold enhancement compared to the response of 2.1 observed for pure TiO₂. The sensor demonstrated rapid dynamic kinetics with response and recovery times of 18 s and 45 s, respectively, and achieved an ultra-low theoretical detection limit of 1.2 ppb. Additionally, the device showed a dominant response to 100 ppb O₃ over representative interfering gases, including NO₂ and CO, as confirmed by a dedicated selectivity bar chart; only limited cross-sensitivity to NO₂ was observed at comparable ppb levels, while the responses to CO and other tested gases remained much smaller. The superior sensing capabilities are elucidated through the synergistic coupling of p-n heterojunctions at the oxide-carbon interface and the introduction of electron-rich pyridinic nitrogen defects, which significantly lower the activation energy for surface redox reactions.

Resumo em Inglês:

ABSTRACT A Inconel 625 transition layer was deposited on the damaged surface of 65Mn steel laser cladding, followed by cladding of a Inconel 625-WC-TiC composite alloy as the working layer. The effects of reinforcement content on the microstructure, elemental distribution, phase constitution, microhardness, and tribological behavior of the composite coatings were investigated. The results indicate that the Inconel 625 transition layer forms sound metallurgical bonding with both the 65Mn substrate and the working layer. The coatings are mainly composed of (Ti,W)C, an (Fe,Ni) solid solution, and carbide phases. The microstructure exhibits a distinct gradient evolution, transitioning from columnar grains near the bottom of the transition layer to a dendrite–eutectic mixed structure in the working layer. The working layer with 30wt.% WC and 10wt.% TiC achieves an average hardness of 480 HV0.2, more than twice that of the substrate, along with a 21.29% reduction in friction coefficient and the minimum wear-scar depth of 0.8μm. Abrasive wear is identified as the dominant wear mechanism. In contrast, the working layer with 40wt.%WC and 0wt.%TiC fails due to through-thickness cracking induced by coefficient of thermal expansion (CTE) mismatch.

Resumo em Inglês:

ABSTRACT Glass fiber–reinforced epoxy composites are used in lightweight structural and sliding components, yet dry-contact damage can shorten service life and generate wear debris. Filler engineering offers a practical route to strengthen the matrix-rich surface while controlling friction and material loss. A coordinated comparison of lubricating, ceramic, and lamellar fillers within a single glass fiber–epoxy platform is still needed. This study aims to assess the mechanical, tribological, and waste-control response of graphite-, SiC-, and MoS₂-filled glass fiber–epoxy laminates. Laminates containing 0, 2, 3, and 5 wt.% filler were fabricated by hand lay-up and compression molding, then tested by tensile, flexural, Shore D hardness, notched Izod impact, ASTM G99 pin-on-disc wear, profilometry, SEM, and response surface modelling. S5 recorded 328 MPa tensile strength, 438 MPa flexural strength, 90 Shore D hardness, and 1.70 × 10⁻⁴ mm³ N-1 m-1 specific wear rate, representing 13.1%, 15.3%, 9.8%, and 39.5% gains over C1. M3 recorded 65 kJ m⁻² impact strength, 0.374 coefficient of friction, and 1.510 µm roughness, giving 12.1%, 40.4%, and 19.8% gains. The results support application-specific filler selection: SiC is suitable for load-bearing wear components, while MoS₂ is suitable for low-friction sliding interfaces. Future innovation should extend validation to high loads, ageing, filler mapping, and multi-criteria ranking.

Resumo em Inglês:

ABSTRACT This study investigates hybrid composite laminates made of onyx and Kevlar fibres for high-strength applications in aerospace and defence. Specimens were fabricated with fibre orientations of 0°, 45°, and 90° and thickness combinations of [10 + 12 + 10], [11 + 10 + 11], and [12 + 8 + 12] mm. This study systematically evaluates the combined effects of fibre orientation and laminate thickness in 3D-printed Onyx–Kevlar hybrid composites to determine the optimal structural configuration for improved flexural performance. Flexural behaviour was evaluated using a three-point bending test, and specimens with 0° fibre orientation exhibited the highest load-bearing capacity and minimum deflection, while specimens with 45° and 90° fibre orientations showed reduced performance. In addition to these general observations, this study establishes a clear structure–property relationship and identifies the most effective laminate configuration among the investigated combinations. Laminates with thicker Kevlar cores demonstrated improved flexural strength due to increased fibre volume fraction. A key achievement of this work is the identification of the 10 + 12 + 10 mm laminate with 0° fibre orientation as the optimal configuration. The maximum flexural strength obtained was 60.9 MPa. This provides a practical design framework for optimizing hybrid composite laminates in additive manufacturing applications.

Resumo em Inglês:

ABSTRACT This study aims to synthesize CaO based inorganic oxide nanoparticles from Aceh bovine bone for transesterification of RBDPO to biodiesel. The synthesis carried out through a sol gel method using different precipitating agents of NaOH and NH4OH, calcined at 700 °C for 4 h. The XRD diffractogram shown the cristalline phases of inorganic oxide nanoparticles resulted from the Aceh bovine bone contained three main compound phases which consisting of hydroxyapatite (Ca10(PO4)6(OH)2), calcium carbonate (CaCO3), and calcium oxide (CaO), the calcination assisted the crystallinity of inorganic particles. FTIR spectra shown the presence of OH-, CO3²⁻, and PO4³⁻ functional groups in the obtained inorganic oxides particles, while the SEM-EDS characterization revealed the obtained inorganic particles has smooth and homogeneous particle morphologies which dominated by Ca, P, and O elements. TEM analysis shown the particle size has been in nanoscale, with most particle sizes of 40 nm for NaOH precipitating agent and 27 nm for NH4OH, whereas the UV-DRS spectra showed the apparent optical band gap energies of 3.1 eV and 3.2 eV, respectively. The synthesized inorganic oxides nanoparticle successful applied for catalizing the transesterification of RPDPO oil into methyl esters, which cointaining methyl palmitate and methyl oleate as predominantly compound.

Resumo em Inglês:

ABSTRACT This study investigates the effects of thermo-mechanical controlled processing (TMCP) and tempering (T) on the microstructure and mechanical properties along the thickness direction of HSLA steel plates. The evolution of microstructure, dislocation density, and mechanical properties was analyzed at the surface, 1/4t, and 1/2t positions using optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD) techniques and mechanical testing. The results show that the microstructure primarily consists of lath martensite and bainite, with the martensite fraction and dislocation density gradually decreasing from the surface to the center due to the cooling rate gradient. Tempering at 300~600 °C promotes recovery of dislocations and carbide precipitation. With increasing tempering temperature, the tensile strength gradually decreases, while the yield strength first increases and then decreases. In contrast, ductility and impact toughness exhibit an opposite trend. The optimal balance of strength and toughness is achieved after tempering at 450 °C, which is attributed to the formation of fine and spheroidized carbides, a moderate dislocation density, and a refined effective grain size. This study not only clarifies the evolution mechanism of microstructure and mechanical properties at different thickness under different tempering conditions, but also provides useful guidance for the industrial production of HSLA steel plates.

Resumo em Inglês:

ABSTRACT This study investigates the synthesis of calcium phosphates (CaP) from aqueous solutions of calcium hydroxide (Ca(OH)2) and phosphoric acid (H3PO4) in the presence of lactic acid (C3H6O3). Emphasis is placed on pH-dependent phosphate speciation and ionic thermodynamic activity and their role in governing phase development during aqueous precipitation. A theoretical equilibrium analysis was performed to evaluate phosphate distribution and calcium availability as a function of pH, establishing a direct link between solution chemistry, supersaturation, and precipitation behavior. CaPs were synthesized under strongly alkaline conditions (pH ≈ 11–12) with reaction times ranging from 14 to 30 min. Continuous pH monitoring revealed distinct transitions associated with precursor dissolution and nucleation. Short reaction times yielded metastable phases, while sintering at 1000 °C promoted transformation toward thermodynamically stable crystalline structures. X-ray diffraction combined with Rietveld refinement demonstrated phase progression as a function of reaction time and thermal treatment, and crystallite size analysis confirmed structural reorganization during sintering. The results demonstrate that pH-driven speciation directly influences intermediate complex formation and final phase assemblage, providing a rapid and controlled route for the synthesis of calcium phosphate ceramics.

Resumo em Inglês:

ABSTRACT The environmental impact of CNC milling was assessed by an energy footprint model based on ISO 14955, which accounts for the electricity consumption, use of lubricant, generation of waste, tool wear, and energy loss in CO2-equivalent emission. Validation was conducted by slot milling of the aluminium alloy A2017 in dry, MQL and conventional flood lubrication. Predicted electrical energy consumption showed good agreement with measured data, with a maximum error of 3.88 %, demonstrating the accuracy of the prediction model. The results demonstrated that the environmental impact was significantly influenced by the lubrication strategy. The use of flood has the most environmental impact as a consequence of much larger lubricant consumption and pumping energy. Dry machining eliminated the lubricant emissions but resulted in faster tool wear and poor surface finish. MQL was considered the best trade-off between machining quality justification and sustainability, given insufficient use of lubricant to lock the boundary layer better than in dry cutting. When considering tool wear and lubricant losses, life cycle assessment demonstrated that MQL has the potential to reduce total CO2-equivalent emissions by 45% over conventional flood lubrication. Therefore, MQL represented the best compromise between machining performance and sustainability in aluminium milling at the considered conditions.

Resumo em Inglês:

ABSTRACT This paper proposes a machine learning-based framework for enhancing the Energy Management System (EMS) and motor health monitoring in electric vehicles (EVs). The EMS uses supervised learning models like Decision Tree, Support Vector Machine (SVM), and XGBoost to sort energy states based on real-time data like temperature, torque, load, and state-of-charge (SOC). The system also includes motor health monitoring by using an Isolation Forest algorithm to find faults without supervision based on changes in motor efficiency, current, torque, and temperature. XGBoost achieved the highest classification accuracy of 93% in predicting EMS control decisions, outperforming SVM and Decision Tree models. Battery health indicators such as State of Health (SoH) are incorporated as additional features to enhance system awareness; however, their direct impact on predictive accuracy is not evaluated in the present study. The suggested EMS framework also cut average energy use by 12.5% compared to traditional rule-based strategies and moved control within 2.8 seconds when a motor fault occurred. These results show that motor condition monitoring analytics could make electric vehicles more reliable, energy-efficient, and fault-tolerant.

Resumo em Inglês:

ABSTRACT Structural health monitoring (SHM) systems increasingly rely on high-dimensional time-series data to identify incipient material degradation and safeguard the operational integrity of critical infrastructure. However, the inherent stochastic noise and complexity of raw sensor data often cause conventional deep learning (DL) models to suffer from elevated computational cost and suboptimal generalization. To address these empirical limitations, this study proposes SAX-1DCNN-BiGRU, a novel hybrid framework that synergizes symbolic representation with advanced DL architectures for robust material degradation monitoring. Specifically, symbolic aggregate approximation (SAX) is introduced as a pre-processing layer to transform continuous acceleration signals into discrete symbolic sequences. This innovative integration effectively mitigates measurement noise and reduces data dimensionality while preserving the essential features indicative of the structural response. Subsequently, the model employs a dual-stage learning process: a one-dimensional convolutional neural network (1DCNN) extracts local spatial features, followed by a bidirectional gated recurrent unit (BiGRU) to capture global, long-term temporal dependencies. The proposed methodology was rigorously evaluated on a finite element model of the Chuong Duong steel truss bridge across diverse scenarios of material degradation. Experimental results demonstrate that the SAX-1DCNN-BiGRU model achieves a superior mean accuracy of 95.63%(5-fold cross-validation, σ = ±1.23%), significantly outperforming standalone baselines (1DCNN, BiGRU, GRU) and standard hybrid variants. Furthermore, the integration of SAX is proven to accelerate convergence and enhance model stability, establishing a highly efficient and noise-resilient model for real-time SHM.

Resumo em Inglês:

ABSTRACT Fluoroelastomers are widely used in demanding applications due to their excellent thermal and chemical resistance, however, their intrinsically low electrical conductivity limits their application in multifunctional systems, especially in the oil and gas industry. The incorporation of graphene has emerged as a promising strategy to improve conductivity, although its influence on peroxide-cured fluoroelastomer compounds processed by internal mixing is still not fully understood, particularly regarding the balance between curing behavior, mechanical properties, and electrical performance. In this study, graphene was incorporated into fluoroelastomer compounds at concentrations of 0.5, 1.5, and 5.0 phr. Cure characteristics, hardness, tensile strength, and electrical conductivity were evaluated. All formulations exhibited similar torque profiles and processing times, indicating good processability even with graphene addition. The curing behavior showed a tendency toward reduced maximum torque and shorter optimum cure time for the formulation containing 5.0 phr graphene. Tensile strength gradually decreased as graphene content increased. In contrast, the compound with 5.0 phr graphene exhibited an increase of approximately 4.7 orders of magnitude in electrical conductivity compared with the unfilled formulation. Overall, graphene contents between 0.5 and 1.5 phr provided the best balance among processability, mechanical performance, and electrical conductivity, minimizing detrimental effects on mechanical properties.

Resumo em Inglês:

ABSTRACT Effective management of water resources demands rigorous quality monitoring, with Chemical Oxygen Demand (COD) serving as a key indicator of organic pollution. Traditionally, COD determination relies on oxidation with potassium dichromate in a strongly acidic medium containing concentrated sulfuric acid and silver sulfate as a catalyst, with mercury sulfate added to minimize chloride interference. The process involves heating under closed reflux, followed by titration of excess dichromate with ammonium ferrous sulfate. Although analytically robust, this method generates hazardous waste containing hexavalent chromium, mercury, silver, and high concentrations of sulfuric acid, posing environmental risks. This study aimed to validate an optimized alternative based on closed reflux digestion coupled with UV–Vis spectrophotometric detection of trivalent chromium, in accordance with Standard Methods for the Examination of Water and Wastewater. To ensure compliance with ABNT NBR ISO/IEC 17025, the method underwent full validation, including selectivity, linearity, limits of detection and quantification, repeatability, intermediate precision, and accuracy. Results demonstrated excellent analytical performance, with precision comparable to the traditional titrimetric method. The approach reduced reagent consumption and toxic waste generation, proving robust, cost-effective, and environmentally sustainable, enabling up to 24 samples per hour and reducing analysis time by approximately 60–70%.

Resumo em Inglês:

ABSTRACT This research explores the creation of sustainable plastic composite bricks that offer improved thermal resistance and the ability to capture carbon. By utilizing recycled plastic waste, Biochar, and various mineral additives, these innovative bricks seek to tackle environmental issues by lowering carbon emissions and promoting effective waste valorization. Experimental evaluations were conducted to assess thermal conductivity, compressive strength, and CO2 absorption capacity. Experimental results showed that Biochar–plastic composite bricks achieved the highest CO2 absorption, averaging 12.8 mg/g. In comparison, plastic bricks without Biochar absorbed only 1.5 mg/g, while traditional clay bricks lacking carbon-capturing components exhibited minimal absorption at 0.2 mg/g. The results demonstrate that the bricks exhibit excellent thermal insulation, structural integrity, and notable potential for carbon interaction performance. This research highlights the potential of plastic composite bricks as a viable solution for eco-friendly construction and pollution mitigation.

Resumo em Inglês:

ABSTRACT This study examines the creation and experimental verification of a nano-engineered exhaust silencer developed to limit harmful emissions while improving the efficiency of a single-cylinder diesel engine. The system consists of a copper–chromium composite casing combined with a nano-coated copper honeycomb insert that strengthens catalytic action without causing excessive exhaust resistance. Thermo-mechanical stability and exhaust flow behavior under high temperature and pressure were investigated through numerical simulations using SOLIDWORKS and ANSYS. Engine trials demonstrated notable reductions in regulated pollutants, including carbon monoxide decreases of up to 40%, hydrocarbon reductions of about 53%, and nitrogen oxide mitigation of 9–12% at full load. Smoke opacity was lowered by 70–80% relative to a conventional silencer. Under optimized operating conditions, carbon dioxide output declined, while elevated residual oxygen levels indicated more complete combustion. Beyond emission control, the modified silencer delivered clear performance benefits, with brake thermal efficiency rising from 14.2% to 31.9% and specific fuel consumption dropping by nearly 24% at maximum load. These improvements are attributed to improved heat dissipation and sustained catalytic effectiveness provided by the nano-coated honeycomb architecture. Overall, the proposed silencer represents a durable, cost-effective, and environmentally sustainable solution for cleaner diesel engine operation.

Resumo em Inglês:

ABSTRACT This research explored the use of Construction and Demolition (C&D) waste as a partial replacement for natural aggregates in concrete and its influence on fresh, mechanical, and durability properties. Results revealed that workability, slump, and setting time decreased with higher C&D content; however, slump showed only a 12% reduction at a 40% substitution rate, remaining within acceptable industry limits. Compressive strength experienced a minimal 4% decline at this level, still meeting construction standards. Durability properties showed some variation: water absorption doubled, sulfate resistance decreased by 27%, and chloride penetration increased by 15%. To predict these behaviors, four machine learning (ML) techniques—Support Vector Regression (SVR), Random Forest (RF), Artificial Neural Network (ANN), and XGBoost—were employed. Among them, the RF model demonstrated superior predictive accuracy for compressive strength, water absorption, and resistance parameters, achieving an R² value of 0.985. Overall, the study concludes that C&D waste can effectively replace natural aggregates without significantly compromising concrete performance. Moreover, integrating ML-based prediction models enables data-driven optimization of concrete mix designs, fostering the production of sustainable, high-performance, and durable concrete with reduced environmental impact. An equation-based numerical model was developed and validated with the experimental and machine learning methodologies to predict the mechanical properties of recycled aggregate concrete. The integrated approach shows the reliable prediction of strength and proof-of-concept for the suitability of recycled aggregates in sustainable concrete construction.

Resumo em Inglês:

ABSTRACT Basalt Fiber Reinforced Concrete (BFRC) is being recognized as an eco-friendly advanced material with reduced environmental footprint, higher mechanical performance and long-term durability. However, its compressive strength prediction still appears to be a difficult problem due to the nonlinearity caused by the interaction of the mix components. This paper demonstrates a production-quality hybrid ML model to predict 28-day compressive strength of BFRC, providing an economical alternative to laborious and expensive laboratory-based testing. A well-defined database of 450 samples is generated involving the essential parameters, such as cement (440 kg/m3), SCMs (110 kg/m3), basalt fiber (0–4.25 kg/m3), fine aggregate (740 kg/m3), and coarse aggregate (975 kg/m3), water (121 kg/m3), superplasticizer (3.52 kg/m3), and curing period (3–365 days). The pre-processed and normalized data were partitioned into the training set (80%) and the test set (20%). Five ML models Gradient Boosting (GB), Cat Boost (CB), Light GBM (LGB), and their hybrid ensembles: GB+CB, GB+LGB were trained and compared using different metrics such as R2, RMSE, MAE, MedAE, etc. Among all ML models, the GB+LGBM model showed the best performance with R2 = 0.9445, RMSE = 5.99 MPa, MAE = 3.62 MPa, and MedAE = 2.26 MPa on the test set. SHAP analysis revealed that coarse aggregates (SHAP ≈+8) and cement (SHAP ≈+7) were the most influential factors, while the remaining water content and the excessive dosage of fiber were disadvantageous. Estimated compressive strength varied from 20 to 140 MPa. This study shows a novel approach by demonstrating the ability of ensemble ML models to capture complex concrete behavior, providing a data-driven approach for sustainable manufacturing of concrete. However, full reliance on the literature-based dataset still has significant limitations, which will increase noise, and these limitations can be further overcome by experimental validation in future studies.

Resumo em Inglês:

ABSTRACT Growing environmental awareness has intensified the search for sustainable engineering materials, particularly natural lignocellulosic fiber–reinforced composites. This study evaluates the impact and ballistic performance of hybrid epoxy composites reinforced with ramie fabric and silicon carbide (SiC) particles. The composites incorporated 30 vol% ramie fabric and 0, 5, or 15 vol% of either micrometric (SiC-M) or nanometric (SiC-N) SiC. Impact resistance was evaluated by Izod impact test, while ballistic performance was assessed through limit velocity (VL) and absorbed energy (Eabs) with .45 caliber. The incorporation of SiC significantly affects both impact and ballistic behavior. The composite containing 15 vol% micrometric SiC (R15SiCM) achieved the highest Izod impact strength (111.68 J/m), outperforming the control ramie–epoxy composite (74.51 J/m) while was statistically superior to all other formulations. In ballistics tests, the composite with 15 vol% nanometric SiC (R15SiCN) achieved the highest absolute Eabs (~315 J). However, this performance was accompanied by substantial variability, attributed to nanoparticle agglomeration and processing-induced heterogeneities, as confirmed by SEM fractographic analysis. Conversely, the composite containing 5 vol% micrometric SiC (R5SiCM) demonstrated a favorable balance, combining high ballistic Eabs (200.11 J) with stable specific energy absorption. Overall, moderate loadings of micrometric SiC provided the most reliable enhancement in both impact and ballistic statistical performance, surpassing nanometric fillers whose tendency to agglomerate compromised consistency. These findings highlight the potential of ramie fabric/SiC hybrid composites as sustainable high-performance materials for impact and ballistic protection.

Resumo em Inglês:

ABSTRACT This study applies machine learning models to thermoplastic injection molding, focusing on the initial tryout stages. These stages are often overlooked in previous research, which concentrates mainly on steady-state production. By analyzing data on temperature, injection pressure, and mass of the parts, we developed a Decision Tree model to identify processing conditions that result in conforming parts. The research demonstrated that mass and injection pressure are critical quality indicators, and intentional variation of these parameters simulated typical tryout adjustments. The results highlighted the model’s ability to predict part compliance with high accuracy, providing a better understanding for precise adjustment of molding parameters, essential for optimizing production and ensuring the quality of injected parts.

Resumo em Inglês:

ABSTRACT The necessity for sustainable construction materials is driving research into alternatives to typical Portland cement, which has a significant environmental impact. This study examines the effect of Nano-Silica (NS) and Calcined Nano-Clay (CNC) on the fresh, mechanical, durability, and microstructural properties of cement mortar. Cement was partially replaced with varying proportions of NS and CNC, and a chemical admixture was used to achieve workable mixes. The behaviour of fresh mortar, strength development at different curing ages, resistance to aggressive environments, and internal microstructure were systematically evaluated. The compressive and flexural strength of NM7 mix (4% NS + 6% CNC) were found to be the highest and the mechanical performances were improved significantly in nano-modified mortars. Compared with the conventional mortar, the durability evaluation showed that the weight loss and strength degradation of the mortar were less under the action of acid and sulphate, and the water absorption was less. The overall results show that the combined effect of NS and CNC effectively improves the strength and durability of cement mortar.

Resumo em Inglês:

ABSTRACT Nickel(II) oxide, Cobalt(III) oxide, and Nickel Cobaltite (NiCo2O4) have been the subject of intense research as pseudocapacitive transition-metal oxides for supercapacitors due to their multivalent redox reactions and outstanding charge-storage property. In this paper, NiO, Co2O3 and NiCo2O4 were prepared via a facile hydrothermal method. Their physical characteristics were studied by XRD, Raman, FESEM, HRTEM and XPS, and their electrochemical behavior was tested in a three-electrode system with 3 M KOH as the electrolyte. XRD analysis, along with Raman spectroscopy data, showed that all the synthesized compounds possessed a monophasic crystal structure. FESEM analysis indicated that NiO possessed aggregated nanoparticles with a nanoscale size, whereas NiCo2O4 possessed a nanostructured surface. Of all the tested electrodes, NiCo2O4 exhibited excellent electrochemical characteristics with a very high specific capacitance (1357.7 F g−1) at a current density of 1 A g−1, very low transfer resistance (Rct = 1.5 Ω), and rapid diffusion rate (2.5 × 10−10 cm2/s). The packaged NiCo2O4/activated carbon asymmetric supercapacitor reached a high energy density at a maximum power density (801 W kg−1) to achieve 42.5 Wh kg−1, high capacitance retention (78%) at 10 A g−1, and exhibited excellent cycling stability with capacitance retention up to 91.8% for 5000 cycles.

Resumo em Inglês:

ABSTRACT This study evaluated the influence of firing temperature on the physical and mechanical behavior of red ceramic blocks produced with partial replacement of clayey soil by açaí seed ash (ASA) at contents of 0%, 5%, 10%, and 15%. Raw materials were characterized through chemical, mineralogical, thermal, and physical analyses. The blocks were fired at 950 °C, 1050 °C, and 1150 °C. At 950 °C, ASA incorporation reduced compressive strength and bulk density while increasing water absorption, porosity, and initial suction. However, from 1050 °C onward, these properties improved, indicating greater densification of the ceramic matrix. The mixture containing 15% ASA fired at 1150 °C showed the best performance, with higher compressive strength and lower porosity and water absorption. The formation of a liquid phase at higher temperatures contributed to pore filling and grain bonding. ASA incorporation did not affect efflorescence. The results demonstrate that the performance of the ceramic blocks depends on the combined effect of residue content and firing temperature. Additionally, the reuse of ASA reduces clay extraction and promotes the valorization of an abundant agro-industrial residue from the Amazon region, contributing to more sustainable ceramic production.

Resumo em Inglês:

ABSTRACT Beam–column joint is the most vulnerable part to earthquake damage in an RC moment-resisting frame. The aim of this paper is to find out the capacity of headed bars and GFRP to bring external RC beam–column joints back to the original structural performance. ANSYS Workbench software was used to create a 3D digital model of beam–column joint. Three places of beam–column joints were studied: (1) normal seismic detailing, (2) headed bars, and (3) X-shaped GFRP wrapping only with the frame region. A beam was cyclically loaded during the loading at beam end while a constant axial load was maintained on the column to simulate realistic seismic conditions. Several structural parameters including total displacement, stiffness, strain energy, and equivalent stress were used to differentiate the performance of the different versions. The findings show that headed bars play an important role not only in transferring the load but also in lessening the joint deformations compared to conventional reinforcement detailing. GFRP-wrapped specimen shows considerably greater stiffness and less displacement due to the confinement effect of the FRP layers. The study concludes that using headed bars and GFRP wrapping together can effectively improve the seismic capability and structural resilience of RC beam–column.

Resumo em Português:

RESUMO Em sistemas de controle de atitude de veículos espaciais e satélites, o fornecimento contínuo de fluido à câmara de combustão é fundamental para garantir a estabilidade, mesmo sob condições adversas como gravidade zero e sloshing. Entre os sistemas de fornecimento, destaca-se a expulsão positiva por diafragmas metálicos. O objetivo deste trabalho foi obter um diafragma metálico em alumínio AA1100 pelo processo de conformação a frio por spinning forming. A caracterização do material incluiu análises de dureza por nanoindentação, avaliando os efeitos do trabalho mecânico a frio sobre a dureza e o módulo de elasticidade, além de ensaios de tração para levantamento das propriedades mecânicas e índices de anisotropia planar (ΔR) e normal (Rm). Para garantir o adequado processo de inversão dos diafragmas, evitando colapsos e flambagem, reduziu-se gradativamente a espessura da membrana do ápice à borda pelo processo de spinning forming. Ensaios hidropneumáticos de inversão foram realizados utilizando água em protótipos com e sem tratamento térmico de recristalização após o encruamento por conformação, permitindo comparar as pressões de expulsão do propelente. A eficiência de expulsão foi medida em dois ensaios específicos, apresentando 94,8% e 95,2%. Concluiu-se que o diafragma de AA1100 apresentou bom desempenho na fabricação e nos ensaios laboratoriais.

Resumo em Inglês:

ABSTRACT In attitude control systems of spacecraft and satellites, the continuous supply of fluid to the combustion chamber is essential to ensure stability, even under adverse conditions such as zero gravity and sloshing. Among the supply systems, positive expulsion using metallic diaphragms stands out. The objective of this work was to manufacture a metallic diaphragm from AA1100 aluminum using the cold forming process of spinning forming. Material characterization included hardness measurements by nanoindentation, evaluating the effects of cold mechanical working on hardness and elastic modulus, as well as tensile tests to determine the mechanical properties and the planar (ΔR) and normal (Rm) anisotropy indices. To ensure a proper diaphragm inversion process in the positive expulsion system, avoiding collapse and buckling, the membrane thickness was gradually reduced from the apex toward the edge by spinning forming process. Hydro-pneumatic inversion tests were performed using water on prototypes with and without recrystallization heat treatment after work hardening by forming, allowing a comparison of the propellant expulsion pressures. Expulsion efficiency was measured in two specific tests, achieving values of 94.8% and 95.2%. It was concluded that the AA1100 diaphragm exhibited good performance during manufacturing and in laboratory testing.

Resumo em Inglês:

ABSTRACT Soft Pneumatic Actuators (SPAs) offer excellent compliance and can handle delicate items with ease; however, they typically cannot generate sufficient stiffness and force required for demanding applications. The existing techniques of producing SPA’s include the molding and casting of silicone rubber, which is a labor-intensive, multi-step process which restricts the design freedom for complicated geometry. This study introduces a novel one-shot 3D-printed PolyJet fabrication technology that allows a stiffer endoskeleton-like support structure to be built directly inside a Pneumatic Network (PneuNet) type SPA in a single print. Five endoskeleton variants were designed and investigated using SPAs: (i) solid rib, (ii) perforated beam, (iii) corrugated shell, (iv) segmented hollow chain, and (v) curved hollow beam. Mathematical modelling and FEA of the SPA were also performed, and the results were experimentally validated. The research findings indicate that embedding an endoskeleton result in a notable improvement in actuator performance. The corrugated shell design offered the best combination of enhanced bending characteristics (93°), tip force (4.2 N), 176% improved stiffness, and stable load handling up to 150 g. A two-finger gripper prototype and soft robotic glove were tested to grasp objects of different shapes and weights, demonstrating the real-world usefulness of the actuator.

Resumo em Inglês:

ABSTRACT Mold contamination and aroma depletion remain critical challenges during tobacco storage. Conventional chemical antifungal agents present residue risks, whereas the direct application of free fragrances is heavily constrained by their rapid volatilization. Herein, we engineered dual-functional core-shell microcapsules via a secondary cross-linking coupled with a vacuum freeze-drying process, encapsulating highly volatile vanillin and citral within a biodegradable chitosan-sodium alginate polyelectrolyte shell. Formulation optimization via an orthogonal array design (L9(34)) identified the optimal parameters as 1.2% chitosan with a 1:2 core-to-wall ratio. Under these conditions, the vanillin and citral microcapsules exhibited high encapsulation efficiencies of 14.23 ± 0.85% and 13.58 ± 0.79%, respectively, alongside highly suppressed 75-day cumulative release rates of 33.8% and 24.8%, respectively. Notably, the citral-loaded microcapsules demonstrated exceptional antifungal efficacy, achieving complete (100.0%) and 96.6 ± 1.1% inhibition against Aspergillus flavus and Aspergillus niger, respectively. Furthermore, during a 28-day accelerated tobacco aging trial, the microcapsule treatment reduced mold proliferation by over two orders of magnitude (>99.8%) and retained >65.0% of key aroma components, substantially enhancing the sensory quality. This study proposes an innovative “distal-proximal” synergistic strategy, providing an efficient, eco-friendly platform for simultaneous microbial control and aroma retention in active preservation materials.

Resumo em Inglês:

ABSTRACT This research examines the structural efficacy of Reinforced Concrete (RC) beam-column connections constructed with both conventional and fibre-reinforced systems, assessed through experimental testing and analytical modelling. A total of four beam-column specimens were prepared, with dimensions of 150 mm × 200 mm × 1350 mm and 150 mm × 150 mm × 1500 mm. The specimens were tested under monotonic loading at full scale, with both ends restrained as fixed supports. The specimens RCC-C, RCC-3D, RCC-4D, and RCC-5D were scrutinized for various parameters, including load-deflection response, ductility, stiffness, energy absorption, energy dissipation, and modes of failure. The results indicated a gradual increase in load-carrying capacity, rising from 32.46 kN in RCC-C to 47.52 kN in RCC-5D. Concurrently, the tensile strength of steel rebars remained consistent across different diameters, with an elastic modulus of 210 GPa, thereby affirming the quality of the reinforcement. The load-deflection analysis illustrated that both yield and ultimate loads increased with the complexity of the fibre, alongside enhanced deflection capacities and ductility factors, thereby confirming improved deformation tolerance. Energy absorption exhibited a notable enhancement, rising from 32.46 J in RCC-C to 47.52 J in RCC-5D, while the dissipation capacity remained stable, suggesting superior toughness without compromising release characteristics. The modes of failure evolved from brittle concrete crushing in RCC-C to ductile mechanisms characterized by flexural plasticity and shear pull-out in RCC-3D and RCC-4D, with RCC-5D demonstrating crack propagation stability. A comparative analysis of the experimental and analytical findings revealed a near-perfect correlation, with mean ratios of 0.996 for deflection and 0.994 for load, accompanied by minimal statistical variation, thereby validating the precision of finite element modelling. The results affirm that advanced reinforcement systems substantially enhance strength, ductility, and energy absorption while ensuring predictable performance, rendering fibre-reinforced beam-column connections exceptionally reliable for contemporary structural applications. The specimens exhibited a gradual enhancement in load-carrying capacity, with values increasing to 14.73% (RCC-3D), 33.58% (RCC-4D), and 46.40% (RCC-5D), relative to the control specimen (RCC-C). This trend indicates that structural performance consistently improved with each successive increment, validating the enhanced resistance and stability at every loading stage.

Resumo em Inglês:

ABSTRACT When tunnels pass through fault zones, excessive ground surface settlement often causes intrusion or even collapse during construction. Compared with previous research paradigms that focus on a single factor or adopt simple superposition, this study comprehensively incorporates various key influencing factors, including shield tail clearance, synchronous grouting, shield axis, as well as shield speed and torque, deeply analyzes the coupling mechanism among these factors, and thus more comprehensively reveals the evolution law of shield tunnel settlement under complex geological conditions. Based on this, this paper combines the finite element simulation of the F236 fault zone with measured data, and introduces various shield parameters to predict the ground surface settlement when the tunnel passes through the F237 fault zone. Establish a finite element model of the F237 fault zone to explore the influence of shield parameters in the fault zone on ground surface settlement and put forward construction suggestions. The results show that compared with the F236 fault zone, the settlement value of the F237 fault zone decreases by 15%, and the simulated settlement curves of both are similar. When the shield machine passes through F237, the upper and lower shield tail clearances are 10% smaller than those when passing through F236. When the shield tail clearance exceeds 30 mm, the settlement risk increases significantly. The reduction rate and fluctuation amplitude of the vertical shield axis in the F237 fault zone are 10% smaller than those in the F236 fault zone. The synchronous grouting amount in the F237 fault zone decreases by 15%, with more stable fluctuations. The “grouting-monitoring-supplementary grouting” cyclic mode is adopted to repair local defects in a timely manner and ensure filling quality. The fluctuation range of the vertical axis in the F237 fault zone is relatively small. Before construction, grouting reinforcement is adopted to improve the stability of the stratum, reduce the difficulty of axis control during the advancement process, and enhance construction stability.

Resumo em Inglês:

ABSTRACT The Vertical Connection Module (VCM) is widely used in the subsea connection of flexible pipelines across the Brazilian coast, and it is among one of the most important pieces of equipment applied for enabling the petroleum mixture, i.e., water, rock particulates, and hydrocarbons, to flow by Vertical Christmas Tree (VXT), Pipeline End Terminal (PLET), Pipeline End Manifold (PLEM), and Manifold up to the offshore platform facilities, such as Floating Production Storage and Offloading (FPSO) vessel. In this work, a sensitivity analysis was performed by Finite Element Method (FEM) considering the application of external loading through a flexible pipeline on the upper flange of a illustrative VCM; tension, shear, and bending moment were individually applied to verify their influence on the structural capacity of the equipment in question using the isotropic hardening model from ASME BPVC.VIII.2 (Annex 3-D) to develop the stress-strain monotonic curves of the materials. The positive and negative directions of the loads were also investigated across the plastic strain levels inferred in step 1, within the interval [0; 2%]. Focusing on the loading magnitude, the VCM exhibited worst mechanical behavior when the pure shear load was applied. Regarding the isotropic hardening model, it was observed that by increasing the plastic strain level in step 1, the VCM capacity was reduced in the subsequent loading cycle, i.e., step 2. An exception to this phenomenology was only observed for small plastic strain levels under negative tension and negative shear loads. The isotropic hardening model enabled a finer understanding of the influence of tension, shear, and bending moment on the VCM structural capacity. These observations can enhance design robustness and establish more reliable constraints for the VCM, ultimately contributing to a safer operational scenario for the Oil & Gas industry in the subsea connection systems.

Resumo em Inglês:

ABSTRACT Fluorosis, a widespread health disorder, is predominantly caused by prolonged ingestion of fluoride-rich groundwater, making fluoride contamination a significant global environmental concern. Conventional coagulants are largely ineffective in removing fluoride across a wide pH range, necessitating the exploration of alternative materials for treatment of fluoride-laden effluents, including mine drainage. This study investigates the fluoride adsorption capacity of calcium (Ca) and magnesium (Mg) impregnated Municipal Solid Waste (MSW) bottom ash in aqueous systems. The influence of contact time, adsorbent dosage, pH, and particle size on fluoride removal efficiency was systematically evaluated. The adsorption mechanism was further elucidated using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy coupled with Energy Dispersive X-ray Analysis (SEM-EDAX), and X-ray Diffraction (XRD). The Ca-impregnated MSW bottom ash exhibited a maximum fluoride removal efficiency of 63.5% at 45 min contact time, 9.1 g/L dosage, pH 6.0, and 75 µm particle size. The Mg-impregnated MSW bottom ash achieved a slightly lower removal efficiency of 62.8% under optimized conditions of 30 min contact time, 6 g/L dosage, pH 6.0, and 75 µm particle size. Although Ca-impregnated bottom ash showed marginally higher fluoride adsorption, Mg-impregnated bottom ash was more efficient at shorter contact time and lower dosage. Adsorption kinetics was modelled using the Yoon–Nelson and Thomas model. The experimental data demonstrated the best fit with correlation coefficients (R2) of 83.63 and 76.35, indicating the suitability of the models for describing fluoride adsorption behaviour. Overall, the findings highlight the potential of Ca- and Mg-impregnated MSW bottom ash as low-cost and sustainable adsorbents for fluoride removal from contaminated water, thereby contributing to environmentally friendly water treatment strategies.

Resumo em Inglês:

ABSTRACT This study the thermal behavior of a floating solar still in the city of Campina Grande, Paraíba, Brazil. The energy balance equations applied to the main regions of the system, including the water, cover, absorber surface, and two insulating layers. For the simulation input data, the Open-Meteo database was used, covering solar radiation, air temperature, relative humidity, wind speed, and atmospheric pressure. Analyses were conducted for the 15th day of each month throughout 2024, representing the typical seasonal variations of the region’s semi-arid climate. The numerical method adopted was a transient 0D multi-region nodal model, suitable for simulations with larger time steps, complemented by a convergence study with 3600 s, 1800 s, 900 s, 300 s, 60 s, and 30 s, allowing the evaluation of production sensitivity to different temporal resolutions. The results demonstrated that time steps below 300 s provide convergent and reliable predictions, with 60 s identified as an optimal compromise between numerical accuracy and computational cost. The results indicated daily freshwater yield values ranging from 0.4 to 3.9 L m–2day–1, with the best performance observed in January and more pronounced limitations in June, associated with lower solar irradiance and higher relative humidity.

Resumo em Inglês:

ABSTRACT The current research examines the mechanical and durability performances of concrete blended with ceramic waste powder (CWP) as partial cement substitute in conjunction with the use of polypropylene (PP) fibers. The experimental design considered the influence of different amounts of CWP and polypropylene fiber reinforcement on the tested parameters. Response Surface Methodology (RSM) was applied in this investigation for optimization and modelling purposes. In this regard, it is clear from the results obtained that 20% CWP with polypropylene fiber reinforcement (CCF + Cr20) represents the optimum mix. This mix gives rise to maximum compressive strength (44.8 N/mm2), which translates into a relative improvement by 33.75% when compared to control concrete. For the same mixture, the split tensile strength was recorded to be 5.6 N/mm2 (improved by 47.35%) whereas the flexural and shear strengths amounted to 7.5 N/mm2 (improvement by 66.65%) and 7.8 N/mm2 (+15.38%), respectively. The mix was seen to show resistance to acidic action and reduced chloride ion penetration. The prediction capability of RSM models developed in this work was validated with an average percentage error of 1.16%, 2.32%, 0.95% and 1.06% for compressive, tensile, flexural and shear strength predictions, respectively. This study concludes that 20% CWP combined with fiber reinforcement provides an optimal balance between mechanical performance, durability, and sustainability.

Resumo em Português:

RESUMO A crescente urbanização global impões desafios para o desenvolvimento de cidades que possam ser habitáveis, robustas e sustentáveis. Nesse contexto, o dióxido de titânio (TiO2) tem se destacado por suas propriedades fotocatalíticas, que permitem a degradação de poluentes quando exposto à luz ultravioleta, e quando incorporado em argamassa de revestimento promove a autolimpeza da superfície. Assim, o presente estudo tem como objetivo avaliar o efeito da adição de TiO2 nas propriedades físico-mecânicas e fotocatalíticas de argamassas de revestimento à base de cimento branco. Foram estudados quatro traços de argamassa contendo adições de TiO2 P25 de 0, 1, 2 e 3%, em relação à massa da argamassa. Foi observado que o aumento da adição do TiO2 reduziu o índice de consistência das argamassas. Entretanto, o teor de 1% contribuiu para o aumento das resistências à flexão e à compressão das argamassas, resultando em 21,74% a mais de resistência a compressão. Sob o aspecto catalítico, a maior eficiência foi para os teores de 2% e 3%, observada pela variação das coordenadas cromáticas no sistema CIELAB, com aumento de em torno de 8% da luminosidade. Portanto, a determinação de teores otimizados de TiO2 em argamassas de revestimento podem promover o equilíbrio entre propriedades físico-mecânicas e fotocatalíticas, tornando-se uma alternativa viável e sustentável para o desenvolvimento de revestimentos autolimpantes na construção civil.

Resumo em Inglês:

ABSTRACT The growing global urbanization poses challenges for the development of cities that can be habitable, robust, and sustainable. In this context, titanium dioxide (TiO2) has stood out for its photocatalytic properties, which allow the degradation of pollutants when exposed to ultraviolet light, and when incorporated into rendering mortar, it promotes the self-cleaning of the surface. Thus, the present study aims to evaluate the effect of adding TiO2 on the physical-mechanical and photocatalytic properties of white cement-based rendering mortars. Four mortar mixes containing additions of TiO2 P25 of 0, 1, 2, and 3%, relative to the mass of the mortar, were studied. It was observed that increasing the addition of TiO2 reduced the consistency index of the mortars. However, the 1% content contributed to increased flexural and compressive strength of the mortars, resulting in 21.74% more compressive strength. From a catalytic standpoint, the highest efficiency was observed for contents of 2% and 3%, as shown by the variation in chromatic coordinates in the CIELAB system, with an increase of approximately 8% in luminosity. Therefore, determining optimized TiO2 contents in coating mortars can promote a balance between physical-mechanical and photocatalytic properties, becoming a viable and sustainable alternative for the development of self-cleaning coatings in civil construction.

Resumo em Inglês:

ABSTRACT The present investigation aims to produce sound weld joints of 316L stainless steel (SS) using the gas tungsten arc welding (GTAW) process with different metal coated filler metals. The filler materials used in GTAW are coated with nickel (Ni), chromium (Cr) and Tungsten (W) / Boron (B) on SS 308L for welding process. The major process parameters of welding, welding current, arc voltage and filler wire diameter and arc length are considered. These coated filler metals were categorized based on the type of coating applied to SS 308L, namely Ni, Ni B, Cr B, Ni Cr B and Ni Cr W/B. Among different metal coatings, Ni Cr–B coated filler wire yielded the second highest tensile strength while the maximum tensile strength of 668 MPa obtained using the Ni Cr–W/B coated filler wire. Moreover, Ni Cr–W/B coated filler metal exhibited the highest impact toughness of 83.64 J which is 69% higher when compared to the plain Ni-coated filler metal. The average micro hardness of welds produced using the Ni Cr–W/B filler metal is approximately 10.08% higher than that of welds fabricated with the conventional Ni-coated filler. Scanning electron microscopy (SEM) used to examine the weldments and HAZ in order to evaluate the influence of various metal coatings on microstructural evolution.

Resumo em Inglês:

ABSTRACT This work presents an optimization framework for the design of a laminated composite aircraft fuselage aimed at maximizing its fundamental natural frequency to mitigate resonance-induced structural failures during flight. While Finite Element Analysis (FEA) and Artificial Neural Networks (ANN) have been widely used for vibration studies, their direct application in large-scale design optimization remains computationally intensive. To overcome this limitation, the present work integrates a Genetic Algorithm (GA) with an ANN surrogate model to efficiently explore laminate stacking sequences under in-plane strength and weight constraints. The ANN, trained using high-fidelity FEA data, enables rapid prediction of natural frequencies across a wide design space, significantly reducing computation time. The integrated FEA–ANN–GA framework successfully identifies optimal ply configurations that enhance structural integrity, vibration resistance, and passenger comfort. The results demonstrate the potential of this hybrid computational approach to improve fuselage dynamic performance and reliability, thereby supporting the growing transition toward composite-based aerospace structures.

Resumo em Inglês:

ABSTRACT This study applies mixture design, ANOVA, and desirability function analysis to optimize concrete performance with river (RS), crushed (CS), dune (DS) sands, and their combinations. Experimental validation confirms the reliability, practical applicability, and sustainability of optimized mixes, while highlighting key property relationships. Study optimized concrete mixes and developed predictive models using a multi-objective desirability approach. Twenty-one mixtures with varying RS, CS, and DS were designed via a three-factor, five-level simplex lattice method. Key properties including slump, 7 and 28-day compressive (CS) and flexural (FS) strengths, capillary absorption, and UPV were measured. ANOVA and statistical modeling in Design-Expert13 validated factor significance and interactions, enabling reliable mathematical models to predict concrete performance. ANOVA results showed strong predictive performance (R2 = 0.80–0.91). RS improves workability, while moderate amounts of CS and DS sands enhance strengths and reduce open porosity. Best 28-day CS (36 MPa) was recorded for the mix consisting of 0.4RS+0.6CS. Ternary mix M10 (20%RS+60%CS+20%DS) achieved the highest 28-day CS, though excessive dune sand (>40%) decreases performance. Model predictions deviated less than 9% from experiments, confirming reliability. Significant correlations (R2>0.91) among CS, open porosity, density, UPV, and dynamic elasticity modulus enable non-destructive assessment. Local sands (CS, DS) are viable sustainable alternatives to RS.

Resumo em Inglês:

ABSTRACT Most projects in India utilized cast-in-situ concrete, despite the widespread use of precast concrete structural technologies globally. The swift increase in India’s population and the scarcity of space led to a significant demand for multistory residential buildings. As a form of natural disaster, Earthquakes inflicted considerable damage on infrastructure and resulted in loss of life. It was determined that the inadequate performance of the connectors was responsible for the failure of the precast constructions. The connections were the most vulnerable aspect of the precast concrete structure. The present study investigated the behavior of precast column-footing connections subjected to monotonic lateral loading. Two half-scale column-footing connection specimens-one conventional and the other precast-were prepared and tested under monotonic lateral loading. These elements were tested under lateral load. The precast column-footing connection was connected using a half-grouted sleeve. The study’s main aim was to investigate the load-carrying capacity, mode of failure, crack pattern, stiffness, energy absorption and ductility of the column-footing connection elements. The half-grouted sleeve precast column-footing connection element performs better than the conventional concrete column- footing connection. The half-grouted sleeve column-footing connection exhibited higher performance than the conventional connection, with increases in load-carrying capacity (8.47%), ductility (27.08%), energy absorption (30.96%), stiffness (2.1%), and energy dissipation (23.28%). The research is recommended for implementation in practical applications.

Resumo em Inglês:

ABSTRACT Abrasive waterjet machining (AWJM) is increasingly adopted for precision cutting of high-strength steels; however, accurate prediction of machining responses remains challenging due to complex nonlinear interactions among process parameters. This study aims to develop a reliable data-driven framework for predicting material removal rate (MRR), surface roughness (Ra), and taper angle during AWJM of naval-grade DMR249A steel. Experiments were designed using a Taguchi L27 orthogonal array considering water pressure, traverse speed, stand-off distance, and abrasive flow rate as control factors. A multi-output deep learning neural network (DLNN) was implemented and systematically tuned to model the nonlinear relationships between input parameters and machining responses. The model performance was evaluated using statistical error metrics and parity analysis. Results demonstrate that the DLNN achieved high predictive accuracy and effectively captured parameter interactions, outperforming conventional regression approaches, particularly for Ra and taper angle. SEM analysis further confirmed the progressive transition from cutting-dominated to deformation-dominated erosion along the jet path. The developed framework reduces reliance on extensive experimentation and supports intelligent process planning for difficult-to-machine steels.

Resumo em Inglês:

ABSTRACT Proposed study examines how sodium chloride (NaCl), magnesium sulphate (MgSO4), and calcium chloride (CaCl2) affect heat retention and energy extraction in a trapezoidal Salt Gradient Solar Pond (SGSP) with sloped walls to reduce sidewall losses and improve gradient stability. Three-layer prototype: upper convective zone (UCZ), non-convective zone (NCZ), and lower convective zone (LCZ) monitoring temperature profiles with K-type thermocouples at 0.1 m intervals, density with hydrometers, and extraction via a copper coil heat exchanger for 14 days under 600 W/m2 ambient irradiation. Energy analysis used heat balance equations for solar absorption, losses, and exergy efficiency. MgSO4 outperforms NaCl and CaCl2 with LCZ temperatures of 95°C, denser gradient (1.25–1.35 g/cm3), 20% NCZ erosion reduction, energy extraction stabilising at 250 kJ/m2/day, 18% thermal efficiency, and 0.85% exergy efficiency vs. 12%/0.6% for NaCl and 14%/0.7% for CaCl2 FESEM study of LCZ crystals shows MgSO4’s irregular aggregates (15–30 µm) improve stability, whereas NaCl’s cubic crystals (10–20 µm) and CaCl2’s needles (5–15 µm) correlate with performance, as confirmed by a 1D finite-difference model. Direct multi-salt comparison evaluates salt-specific heat retention and energy extraction. MgSO4 achieves 95°C LCZ, 250 kJ/m2/day extraction, 18% thermal and 0.85% exergy efficiency 15× and 10× higher than NaCl and CaCl2, respectively.

Resumo em Inglês:

ABSTRACT This study evaluated the technical feasibility of incorporation of LSS into base concretes for rigid pavements and focusing on enhanced properties of the concrete. Two approaches were employed here, and two reference mixtures – designated as A-0 and S-0 – were designed. These two approaches are as follows: (a) simple additions of 1% (A-1), 1.5% (A-1.5), and 2% (A-2) of LSS as a fiber; and (b) LSS contents of 10% (S-10), 20% (S-20), and 30% (S-30) replacing part of the natural sand fraction of the base concrete. Workability was monitored in the slump test, whereas the hardened properties included compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity. Flexural strength considerably improved after incorporation of LSS, whereas the best results in compressive strength and splitting tensile strength were observed for S-10 and S-20. The modulus of elasticity mainly decreased probably due to the reductions in the compressive strengths and the lack of homogeneity of the mixtures. The S-10 material overall provided the best findings, and its application in rigid pavements may occur after adjustments in the dosage. Hence, LSS can be effectively utilized as a viable and sustainable alternative for reinforcement in cement concrete for rigid pavements.

Resumo em Inglês:

ABSTRACT Eu3+-doped YPO4 ceramic powders (6 mol%) synthesized via a solvothermal approach exhibit a high absolute quantum yield of 62%, highlighting the importance of controlled synthesis conditions for enhanced luminescent performance. Optimized parameters produced highly crystalline, quasi-spherical nanoparticles (~45–50 nm) with low defect density, favoring efficient radiative recombination processes. Structural analyses confirm the substitution of Eu3+ into Y3+ lattice sites without secondary phases or significant lattice distortion, while spectroscopic results indicate preserved local symmetry around the emitting centers. TEM and SEM micrographs reveal uniform morphology and narrow size distribution, and HRTEM shows clear lattice fringes consistent with XRD data. SAED patterns further confirm high crystallinity and phase purity of the synthesized powders. The dominant 5D0→7F1 emission, asymmetry ratio (R21 = 0.958), and long decay lifetime (3.8 × 10−3 s) indicate efficient energy transfer and reduced non-radiative losses within the host lattice. The high quantum yield arises from the combined effect of crystallinity, morphology, and controlled synthesis conditions. Consequently, YPO4:Eu3+ exhibits stable and intense orange–red emission, making it a promising material for optoelectronic applications such as LEDs, sensors, biosensors, and anti-counterfeiting technologies in advanced photonic systems.

Resumo em Inglês:

ABSTRACT This study introduces a novel multi-criteria decision-making (MCDM) framework that uniquely integrates aerodynamic gust loading, turbulence intensity, and fiber-matrix interfacial adhesion to select sustainable composites for unmanned aerial vehicle (UAV) wings. The primary objective is to identify optimal biodegradable and conventional materials that balance structural performance, environmental sustainability, and aerodynamic resilience under harsh desert-coastal wind conditions. Using advanced micromechanical models and a two-step MCDM methodology, natural fibers (ramie, flax, hemp, banana) reinforced with epoxy and polylactic acid (PLA) matrices were systematically evaluated against E-glass composites. Properties were normalized for density, strength, and modulus, followed by dynamic gust-induced sensitivity analysis incorporating realistic adhesion coefficients. Results demonstrate that ramie/epoxy achieves the highest overall score (0.855), excelling in specific stiffness and flutter resistance, while flax/epoxy delivers the most balanced structural profile (0.811). For fully biodegradable applications, ramie/PLA emerges as the optimal candidate (0.759), exhibiting the lowest performance degradation under extreme gust loading (49.1%). The study establishes a robust sustainable material selection framework for lightweight UAV structures and provides practical guidance for future biodegradable aerospace composite design, aeroelastic optimization, and environmentally responsible UAV manufacturing.

Resumo em Inglês:

ABSTRACT Polyamide tribosystems are used in gears, bushings, bearings, and guide elements, where friction and wear constrain efficiency and durability. Bio-based lubricants are significant in this field because polar fatty acid esters can form boundary films while reducing reliance on petroleum oils. This work evaluates the friction and wear of PA6, PA66, PA66GF30, and PA66MoS2 against EN31 steel to identify sustainable material–lubricant pairings. Pin-on-disc tests were conducted at 40–60 N and 150–250 rpm over 1000 m, and SEM, ATR-FTIR, profilometry, XRD, and XPS were used to characterize the worn surfaces. PA66MoS2 exhibits the lowest friction and wear because MoS2 basal-plane shear and polar bio-oil adsorption operate concurrently. The coefficient of friction decreased from 0.061 in dry sliding to 0.028 with a 75% rice bran oil/25% sunflower oil blend at 60 N and 250 rpm, corresponding to a 54.1% reduction, and the specific wear rate fell to 0.18 × 10−4 mm3/N·m. A carbonyl band near 1740 cm−1 and reduced MoO3 formation confirm stable adsorbed tribofilms. These findings establish rice-bran-rich lubrication with MoS2-filled PA66 as a viable route for efficient polymer sliding components. Future innovation will focus on cyclic thermal loading, oxidative ageing, and sustainable validation.

Resumo em Inglês:

ABSTRACT Studies involving composites with recycled polymer matrices have attracted the attention of several researchers as an alternative to reduce the high volume of polymeric materials discarded into the environment. In this context, composites reinforced with natural fibers stand out as a sustainable option, in addition to contributing to the improvement of the mechanical properties of these materials. The objective of this work was to develop composites using sugarcane fibers as filler for the production of extruded polypropylene (PP) and polyacrylonitrile-butadiene-styrene (ABS) sheets. Formulations containing 5% and 10% by mass of sugarcane fiber in PP and ABS matrices were evaluated. The samples were characterized by differential exploratory calorimetry (DSC), tensile and elongation tests, as well as morphological analyses performed by scanning electron microscopy (SEM) and optical microscopy. The results showed that the addition of fiber increased the maximum stress for both polymer matrices. For ABS, increases of 7.3% and 9.4% were observed for composites containing 5% and 10% fiber, respectively, while for PP the increases were 2.1% and 4.8%. Conversely, a reduction in specific deformation was observed in all composites, being more pronounced with increasing fiber content, indicating a loss of ductility in the reinforced materials.

Resumo em Inglês:

ABSTRACT This work aims to contribute to metal processing in the semisolid state by analyzing the microstructural behavior of the Al4.5Cu5Zn under two production routes: conventional (without a grain-refining alloy) and grain refinement. The alloy was reheated to the working temperature corresponding to a 45% solid fraction (608 °C) and maintained for various heat treatment times; the samples were then examined using metallographic techniques to evaluate their behavior. The conventionally produced alloy samples showed deficiencies in primary globule size, grain size, circularity shape factor, and rheocast quality index. Conversely, the samples produced via the grain refinement method yielded satisfactory results across all analyzed parameters, with a 55 μm reduction in average primary globule size, a 25 μm decrease in average grain size, a 0.10 increase in the circularity shape factor, and a 0.03 increase in the rheocast quality index. Additionally, the reheating treatment time influenced the results, with 60 seconds identified as the optimal duration for both production routes. This suggests that the phenomena of Ostwald ripening and coalescence primarily occur within this timeframe. Specifically, as treatment time increases, smaller dendritic arms dissolve and are incorporated into larger ones, reducing the number of dendritic arms (Ostwald ripening), while secondary dendritic arms also tend to coalesce (coalescence).

Resumo em Inglês:

ABSTRACT The transition toward sustainable construction necessitates the strategic reuse of demolition waste as a substitute for virgin aggregates. While environmental and economic benefits are clear, the challenge lies in the inferior mechanical properties typical of recycled materials compared to natural stone. This research addresses these limitations by exploring the synergy between Crushed Brick Aggregates (CBA) and Manufactured Sand (M-Sand). By optimizing these components, the study encourages denser matrix formation and improved interfacial bonding. The objective is to engineer a moderate-strength composite that balances environmental goals with structural requirements. Fresh and hardened state characterizations, specifically workability, density, and mechanical strengths, were conducted to assess the performance of the proposed concrete. The roles of CBA and M-Sand were scrutinized via experimental protocols and enhanced through statistical modelling. Mix optimization was achieved using RSM and CCD, with model reliability confirmed through ANOVA. The interaction of variables was graphically represented in 3D response surface plots, leading to the conclusion that a 40% CBA and 60% M-Sand configuration is optimal for cost-effectiveness and sustainability. Microstructural validation through thin-section analysis evidenced a robust aggregate–matrix bond, corroborating the measured mechanical improvements.

Resumo em Inglês:

ABSTRACT In today’s world, renewable energy sources are picked to generate clean energy in the production process, hence giving them a natural efficiency and environment benefits. Although, solar photovoltaic (SPV) is a source of renewable energy that is very attractive, widespread appropriation continues to be hindered by the use of massive land areas. The systems of polycrystalline floating solar photovoltaic (FSPV) have been developed with an aim to overcome this challenge and respond to rising needs for renewable energy. Many Maximum Power Point Tracking (MPPT) algorithms are used in FSPV systems to ensure efficient extraction of power from the solar panels in various operational conditions. A novel approach using the Dual Inductor Boost Converter (DIBC) in conjunction with MPPT through Random Forest (RF), Perturb and Observe (P&O), Artificial Neural Network (ANN) based machine learning algorithm has been developed to maximize the output power of FSPV systems. The research findings revealed that the proposed FSPV-RF algorithm outperforms in efficiency of the FSPV-RF, FSPV-ANN, FSPV-P&O and FSPV without any control by 17.69%, 19.02%, 19.88%, and 20.76% respectively. The proposed FSPV-RF enviro-economic evaluation indicates that 25.82 tons of CO2/year can be prevented from being released into environment.

Resumo em Inglês:

ABSTRACT In this paper, curved thin-walled specimens of nickel-based single crystal superalloys with film cooling holes of four different ellipticities, namely λ = 1.1, λ = 0.9, λ = 0.7, and λ = 0.5, are designed. Based on the crystal plasticity theory, the stress distribution and crystal slip characteristics of these curved thin-walled specimens with film cooling holes of different ellipticities are analyzed under the condition of 980 °C. The results show that film cooling holes with different ellipticities have a significant influence on the stress distribution and crystal slip characteristics of curved thin-walled specimens. The Mises stress decreases as the ellipticity λ decreases. Furthermore, variations in ellipticity substantially alter the distribution of resolved shear stress around the film cooling holes, shifting the location of the concentration zone. Due to the geometric differences between the inner and outer walls of the bent structure, the resolved shear stress distribution curves extracted from the inner wall to the outer wall for different ellipticities are not symmetric. The resolved shear stress at the outer wall of the curved surface is significantly higher than that at the inner wall. Under different ellipticities, the slip systems corresponding to the maximum resolved shear stress around the film cooling hole all include τ1, τ3, τ4, τ5, τ7, τ9, τ11, and τ12.

Resumo em Inglês:

ABSTRACT Mixed matrix ultrafiltration membranes based on polyacrylonitrile (PAN) and aminated MIL-125(Ti) (NH₂-MIL-125(Ti)) were fabricated by non-solvent induced phase separation for the treatment of oil-in-water emulsions. NH₂-MIL-125(Ti) nanoparticles with disc-like morphology and high crystallinity were successfully synthesized and incorporated into PAN at loadings of 0.5–5.0 wt%. Structural, chemical, wetting, mechanical, and thermal analyses confirmed successful MOF incorporation and showed that membrane hydrophilicity, porosity, surface area, and tensile strength improved up to an optimal filler loading of 2.0 wt%, whereas excessive loading caused partial aggregation and pore blockage. The optimized M3 membrane exhibited a water contact angle of 45.1°, BET surface area of 43.7 m²/g, tensile strength of 5.2 MPa, and pressure-normalized pure water flux of 552.1 ± 18.4 L·m⁻²·h⁻¹·bar⁻¹. During filtration of a 1000 mg/L soybean-oil-in-water emulsion, M3 maintained 99.7 ± 0.2% oil rejection, retained approximately 68% of its normalized flux after 60 min, achieved a first-cycle flux recovery ratio of 96.2%, and showed an irreversible fouling ratio of only 3.8%. The improved performance is attributed to the combined effects of enhanced surface hydration, additional water-transport pathways, and weaker oil adhesion at the hydrated MOF-containing interface. These results indicate that NH₂-MIL-125(Ti) is an effective functional filler for constructing high-flux and fouling-resistant PAN membranes for oily wastewater treatment.

Resumo em Inglês:

ABSTRACT Structural applications need light weight with high strength materials to exhibit high performance. In this research, AL8079 is reinforced with titanium di boride (TiB2) in 0, 5, 10, 15 and 20 wt.% by stir casting. The manufactured AL8079 based composites are solution treated and aged for enhancing the mechanical properties of composites. Solution treated and aged and non-treated AL8079 composites are subjected to Energy Dispersive X-ray Analysis and Scanning Electron Microscope to confirm the presence of elements and study the microstructure of solution treated and aged AL8079 composites. Besides, non-treated and solution treated and aged AL8079 based composites are subjected to determine micro hardness, compression and impact. The inclusion of TiB2 enhances microhardness, compressive strength and impact strength up to 15wt.% and decreases by inclusion of 20wt.% in both non-treating and solution treated and aged conditions. TiB2 significantly enhances the tensile strength of AL8079, peaking at 15wt.% with 42.6% increase, though ductility drops by 50.7% due to embrittlement. At 20wt.% suggests agglomeration effects, and heat treatment further improves overall mechanical performance. The higher microhardness 136HV, compressive strength 299 MPa and impact strength 3.52J are obtained in solution treated and aged AL8079/15wt.%TiB2 composite which are higher than other proportions.

Resumo em Inglês:

ABSTRACT Geopolymer concrete is a sustainable substitute for ordinary Portland cement which minimizes carbon dioxide emissions and effectively utilizes the waste from industries. Proper predictive estimating compressive strength can assist in the mix deign optimization, structural reliability. The article presents a machine learning-based framework to predict the compressive strength of geopolymer concrete made with multiple industrial by-products as binders. This study investigated the subsequent strength of concrete when subjected to fly ash, ground granulated blast furnace slag, metakaolin, silica fume, and rice husk ash. A database was developed containing 243 experimentally prepared samples with different mix proportions. The study conducted the compressive strength prediction by implementing Artificial Neural Network (ANN) and Random Forest (RF) models in Python. The performance of model was analyzed through the coefficient of determination (R2) and mean absolute error (MAE) and root mean square error (RMSE). The RF model was found to be superior to the ANN model with R2 = 0.97, MAE = 1.9969, RMSE = 3.0586, which was an accurate result whereas ANN model was lower accurate R2 = 0.78. The results show that techniques using ensemble learning can capture complex non-linear relationships, reduce experimental efforts and assist in developing efficient and sustainable geopolymer concrete mix designs.

Resumo em Inglês:

ABSTRACT In this work, a four-step process was developed to fabricate Al2O3-based composites synergistically reinforced with in situ generated ZrO2 and SiCw. First, a homogeneous Al2O3/SiO2/ZrO2+C precursor was prepared by SCS method. Second, the precursor was converted into Al2O3/SiCw/ZrO2 composite powder through carbothermal reduction, water washing, and air calcination. Third, the composite powder was first mixed with a PVA solution by ball milling, and the resulting mixtures were then pressed into form a green compact of Al2O3/SiCw/ZrO2. Finally, the green compact were sintered by the APS method to obtain five Al2O3/SiCw/ZrO2 composites (denoted as ASxZy). The mechanical properties and wear resistance of the five ASxZy samples were investigated. The results indicate that the friction coefficients of the five ASxZy samples range from 0.6 to 0.7. Among them, the AS10Z20 sample exhibits the lowest wear rate and the best overall mechanical properties. In these ASxZy samples, SiCw mainly inhibits crack propagation and dissipates fracture energy through whisker bridging, whisker pull-out, and crack deflection, whereas ZrO2 mainly contributes to toughening through crack deflection and microcrack toughening. The dominant wear mechanism of four SiCw-containing ASxZy samples is fatigue wear, whereas that of the AZ30 sample without SiCw is adhesive wear.

Resumo em Inglês:

ABSTRACT Ultra-fast electric vehicle (EV) charging stations operating at power levels above 350 kW introduce critical challenges related to grid peak demand, high operating cost, renewable intermittency, and battery stress. This paper presents a machine learning-enabled energy management system for a hybrid renewable-powered ultra-fast charging station integrating photovoltaic generation, battery energy storage system, dispatchable auxiliary sources, and grid supply. The proposed EMS operates at a supervisory level and coordinates energy flows under stochastic EV charging demand, time-varying electricity tariffs (₹4–₹10/kWh), and uncertain renewable generation. A learning-based decision framework is developed using a reinforcement learning policy trained over 150 episodes, incorporating renewable and EV demand forecasts with ±10% uncertainty. The EMS performs multi-objective optimization by minimizing grid energy cost and peak power demand while achieving a balanced trade-off between renewable energy utilization, grid stability, and economic performance, and maintaining battery state-of-charge within safe operating limits (0.2–0.9). Simulation results over a 24-hour operating horizon demonstrate that the proposed ML-EMS achieves a 20–35% reduction in total grid energy cost, 25–40% peak grid power reduction, and achieves a balanced trade-off between renewable utilization, grid stability, and economic performance compared to a conventional rule-based EMS. The results validate the effectiveness of machine learning-driven energy management for reliable, grid-friendly, and cost-efficient operation of next- generation ultra-fast EV charging infrastructure.

Resumo em Inglês:

ABSTRACT In this work, we investigate the equilibrium atomic structure of the Cu/Ta interface in the Ta–Cu system, focusing on the Nishiyama–Wasserman orientation relationship, by means of atomistic simulations employing angular-dependent potentials (ADP). Two distinct lattice-mismatch regions, denoted as ZI and ZII, are identified at the interface. The static properties of vacancies and solute–vacancy complexes are systematically analyzed within the first interfacial planes. We find that the vacancy formation energy strongly depends on the local interfacial environment, exhibiting significant variations between ZI and ZII. For solute–vacancy complexes, both binding energies and exchange migration barriers are calculated, revealing noticeable deviations from their corresponding bulk values. Furthermore, the vacancy–solute interaction is found to depend sensitively on the distance from the interface core. In particular, vacancies located on the Ta side act as efficient traps for Cu atoms, promoting an enhanced Cu solubility in the interfacial region. These results provide insight into defect energetics and solute behavior at Cu/Ta interfaces.

Resumo em Inglês:

ABSTRACT This study evaluated the influence of mix proportion and water/cement ratio on the mechanical and thermal performance of cement rendering mortars incorporating fines from ornamental stone processing (Fibro) as partial replacement of natural sand. A full 32 factorial design was adopted using three mix proportions (1:1:5, 1:1:6, and 1:1:7—cement:Fibro by mass) and three water/cement ratios (1.0, 1.2, and 1.4), resulting in nine formulations. Cement consumption was maintained constant at 195 kg/m3. The aggregates were characterized by particle size distribution and specific gravity analyses. Compressive strength and thermal conductivity were experimentally determined, and the results were statistically analyzed using analysis of variance (ANOVA). Both investigated factors significantly affected compressive strength, whereas thermal conductivity was predominantly influenced by mix proportion. The highest compressive strength values (>7 MPa) were obtained for the 1:1:5 formulation with w/c = 1.0. Thermal conductivity ranged from 1.23 to 1.74 W/m·K and was associated with variations in matrix densification and pore structure. The results indicate that the incorporation of ornamental stone fines is technically feasible and enables the adjustment of mechanical and thermal properties through mix-design control.

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ABSTRACT This work presents an automated methodology for identifying inorganic compounds from powder X-ray diffraction (XRD) patterns using convolutional neural networks (CNNs). Crystallographic information files (CIFs) were automatically retrieved from the Crystallography Open Database (COD) and processed to generate theoretical diffractograms, including peak positions and intensities derived from structure factor calculations. A total of 33,180 inorganic compounds were processed. To enable CNN-based classification, diffraction patterns were transformed into RGB images using the DeepInsight approach combined with t-distributed stochastic neighbor embedding (t-SNE), allowing the homogenization of feature dimensionality across the dataset. The resulting images were used to train a convolutional neural network for feature extraction, followed by fully connected artificial neural network layers for multiclass classification. The proposed model achieved an average classification accuracy of 69% across 33,180 classes. Compared to traditional search–match approaches, this method reduces computational complexity and eliminates the need for manual interpretation of diffractograms. This work represents a fully automated pipeline integrating data acquisition, diffractogram generation, image transformation, and large-scale compound identification. The results demonstrate a modest yet promising performance, highlighting the dependence of the approach on the selected CNN architecture.

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ABSTRACT Concrete is brittle substance whose tensile strength and flexural strength are low and may easily crack and its lifespan is limited. The proposed research aims at assessing how the addition of nylon fiber affects the mechanical and workability of M30 grade reinforced cement concrete (RCC). The originality of this study is that the nylon fibers used are used at optimal dosage (0.25% and 0.5% by volume) in order to improve both strength and durability without impairing the workability. Six series of specimens were cast and experimented on compressive, split tensile and flexural strength, and slump cone testing of fresh concrete workability. The findings showed that the compressive, split tensile and flexural strengths were increased by 11, 14 and 17 percent respectively by the addition of 0.5 percent nylon fiber over plain M30 concrete. The enhancement in mechanical performance is attributed to improved fiber matrix interfacial bonding and crack-bridging mechanisms provided by the dispersed nylon fibers. The fibers effectively delay crack propagation and redistribute tensile stresses within the concrete matrix. Engineering wise, the nylon fiber-reinforced concrete is a cost-effective and structural-friendly substitute of structural application in which enhanced tensile and flexural strengths are needed.

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ABSTRACT Considering the chloride permeability and mechanical characteristics of cement-based materials in cold marine environment are significantly affected by coupling action of freezing and thawing cycles as well as chloride penetration during early curing phase, a serial of experimental measurements were conducted to study the influence degree of curing age and salt freeze-thaw (SFT) environment on chloride permeability as well as mechanical characteristics of early age cement-based materials in present study. Firstly, salt freeze-thaw tests were conducted after representative curing age, i.e., 3, 7, 14, and 28 days. Then experimental tests for chloride permeability and mechanical characteristics were conducted after certain number of SFT cycles to determine the chloride concentration, compression strength, mass loss, and the relative dynamic elastic modulus (RDEM). Experimental results showed that with the decrease of curing age, both chloride permeability and mechanical characteristics degenerate apparently. Meanwhile a noticeable effect of curing age on cement-based materials suffered from SFT environment was detected: chloride diffusion coefficient, compression strength and RDEM of specimens after early curing age firstly increase slightly and then decrease dramatically. This study confirmed that early curing age play a critical role in chloride permeability and mechanical characteristics of cement-based materials subjected to SFT environment.

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ABSTRACT In almost all machining processes there are several constraints associated and the objective functions are in conflict with the another objective function. In these situations, where equal importance is to be given to all constraints, multi criteria decision making is involved to determine the best optimal solution taking into consideration of all the objective functions in the turning process of AISI4140 steel. In this paper, PEG, PSI and CURLI method are employed. The PEG provides effective discrimination among the alternatives and ranking of alternatives is done effectively without any transition. PSI method is used in identifying the suitable alternatives without assigning the subjective weight assignment. In CURLI method, pairwise scoring matrix is obtained by computing the pairwise absolute difference between the values of the each alternative. Gini index is used in this work to quantify the level of disagreement among the PEG, PSI and CURLI ranking results for each alternative. In this work, PEG and CURLI approaches for MCDM for turning process parameters for AISI 4140 steel, the experimental run ‘#A14’ achieved the highest utility value and minimum radial deviation from the ideal solution, resulting combined acceptance of superior productivity in achieving minimum surface roughness and maximum MRR.

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ABSTRACT To achieve effective in-depth control of injection water for the heterogeneous reservoir of offshore oilfields, a new profile control agent is developed. The co-polymer is prepared by using the cross-linking method with AM and the cross-linker. After the polymer is treated by grinding control technology, the dispersed co-polymer micro-particle gel (DMG) is prepared. Results show that DMG is made of pseudo-spherical particles, and sizes can be controlled from nm to μm by adjusting shearing rates, and thus indicating a good injectivity. The preparation is easy-handling, economical, heat-resistant, and environmental-friendly. When the concentration of monomer (5%) and AM/MBA mass ratio (250:1) are fixed, the effect of shearing rates and time on the viscosity and particle sizes is tested. Results show that the grinding rate and time have great influence on particle sizes. The experimental results of the plugging effect under simulated formation conditions show that the dispersed co-polymer micro-particle gel has good injectivity, deep migration ability and plugging performance. Under the same dosage, the plugging effect of the dispersed co-polymer micro-particle gel is significantly better than that of polymer gel. The dispersed co-polymer micro-particle gel has great application value in profile adjustment of offshore oilfield in middle and high water cut stage.

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ABSTRACT Hydrogen energy has attracted considerable attention and stimulated discussions as a favorable vector for the sustainable energy transition that is increasingly being pursued worldwide. This article presents an analysis of the possible impacts of hydrogen on the energy transition of Brazil and Paraguay. Due to the diversity of possibilities for the use of hydrogen, its inclusion as an energy vector in energy matrices is particularly relevant both in the analysis of each of the two countries individually, as well as their common points and complementarities due to their shared border and energy integration. The results describe, analyze and compare the strengths, weaknesses, opportunities and threats of each country, aiming to contribute to their national strategies. Political, economic, social, technological, environmental and legal scenarios are also considered, verifying whether they are aligned with international strategies. The objective is to evaluate whether Brazil and Paraguay are adequately prepared to participate in the “Hydrogen Economy”, considering the potential impacts of including hydrogen as an energy vector in their energy matrices, seeking to contribute to increasing potential benefits and mitigating potential environmental, economic and technical problems associated with hydrogen production. It presents potential results in the areas of energy generation, as a component of industrial decarbonization and transportation, establishing relationships with theoretical references and analyzing the implications in the energy context. It explores the impacts of the hydrogen economy and its prospects, considering the challenges and opportunities for its implementation in energy matrices and presents conclusions and suggestions for the continuous improvement of the hydrogen economy in both countries.

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ABSTRACT In recent days, the corrosion of steel reinforcement has emerged as a significant concern for Civil engineers in the construction industry. As a result, considerable attention has been directed toward developing methods to predict the service life of reinforced concrete structures. Corrosion often remains undetectable until visible signs such as cracking or delamination appear. To deduce this, electrochemical methods are traditionally utilized to observe its development. Among these, the half-cell potential measurement technique is extensively applied to evaluate the possibility of corrosion. This research develops a method for determining the probability of steel rod corrosion using the half-cell potential technique. The evaluation applied a galvanostatic method on 10 mm, 12 mm, and 16 mm in diameter steel rods. Corrosion potential (Ecorr) and concrete resistivity (ρ) measurements were recorded at every point on a pre-determined interval. A predictive model in SPSS was built to forecast each rod corrosion rate and ultimate tensile strength. The experimental results corresponded closely with the predicted values, with percentage differences of 3.4%, 2.6%, and 0.9% for the 10 mm, 12 mm, and 16 mm rods, respectively. These observations validate that electrical resistivity is a most appropriate and good indicator for forecasting steel reinforcement corrosion rate and tensile strength.

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ABSTRACT Controlled Low Strength Material (CLSM) is a cementitious, self-compacting, and fluid-like material used as a backfill in place of compacted soil. This study analyzes CLSM engineering qualities using industrial wastes GGBS and WFS. The Paste Volume Ratio (PVR) ranged from 0.5 to 0.55, the Portland cement to Cementitious material (pc/cm) ratio was kept constant at 0.1, and the Water to Cementitious material (w/cm) ratio varied from 0.8 to 1. Trial research set the w/cm ratio. Segregation increases with w/cm greater than 1 and workability decreases at 0.5. We examined how PVR and w/cm ratio affect flowability, bleeding, density, compressive strength, and ultrasonic pulse velocity. Experimental results show that the produced CLSM mixtures flowed from 282 mm to 450 mm and bled 1% to 2.3%. The mixtures had a density of 1242–1343 kg/m3. Compressive strength at 28 days ranged from 4.81 to 7.95 MPa, with M2 Mix being strongest. CLSM matrix internal compactness varied between 2.741 km/s and 3.631 km/s, as measured by ultrasonic pulse velocity (UPV). The created CLSM combinations meet ACI 229R criteria, proving that GGBS and WFS can provide a sustainable CLSM with good fresh and hardened qualities.

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ABSTRACT The high- and low-temperature performance requirements of asphalt binders are often contradictory, creating challenges for pavement construction in regions with extreme climatic variations. To address this issue, an SBS/CR modified blended asphalt was developed for Xinjiang, China. Karamay 90# asphalt and Tahe 60# asphalt were blended to prepare the base asphalt, and styrene-butadiene-styrene (SBS), crumb rubber (CR), a compatibilizer, and a stabilizer were incorporated to produce the composite modified asphalt. The prepared binders were evaluated through conventional property tests, elemental analysis, Fourier-transform infrared spectroscopy, SARA analysis, multiple stress creep recovery (MSCR), dynamic shear rheometer (DSR), bending beam rheometer (BBR), thermal analysis, and fluorescence microscopy. The results showed that the SBS/CR modified blended asphalt exhibited superior high-temperature rutting resistance and low-temperature cracking resistance compared with SBS-modified asphalt, CR-modified asphalt, and blended asphalt. Quantitatively, it showed a Jnr value of 0.1192 kPa−1 at 3.2 kPa and the lowest Jnr-diff value of 202.82%, indicating improved resistance to permanent deformation under heavy loading. According to the Superpave performance grading system, the SBS/CR modified blended asphalt achieved PG 82 at high temperature and PG -40 at low temperature. Fluorescence microscopy revealed that the compatibilizer and stabilizer promoted the uniform dispersion of SBS and CR, forming a continuous network structure that enhanced the overall viscoelasticity of the asphalt binder. Based on these findings, suitable material compositions were recommended for different climatic zones in Xinjiang, providing technical guidance for modified asphalt design in regions with demanding climatic conditions.

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ABSTRACT Reinforced concrete (RC) structures in aggressive environments are highly vulnerable to rebar corrosion, which causes volumetric expansion of corrosion products and leads to cracking and deterioration of the surrounding concrete. Reliable prediction of corrosion-induced damage is therefore crucial for evaluating structural durability and safety. However, many existing phase-field modelings treat concrete as a homogeneous material and neglect its inherent multiphase microstructure as well as the mechanical behavior of interfacial regions between phases. Moreover, these phase-field formulations often fail to satisfy the orthogonal condition between the tensile and compressive components of the strain tensor, which is essential for preserving elastic energy in brittle materials. Therefore, this study develops the phase-field computational frameworks to simulate damage evolution in RC structures subjected to corrosion-induced expansion. Two phase-field modelings are proposed: one considering interfacial damage between different phases while enforcing the strain tensor orthogonal condition (Model M1), and another modeling neglecting interfacial damage but still satisfying this orthogonal requirement (Model M2). Numerical simulations investigate crack propagation and rust expansion values in various structural configurations, including different concrete cover thicknesses, confined and unconfined structures, and randomly distributed inclusions with complex shapes. The obtained results show that: (i) the multiphase characteristics of concrete significantly influence corrosion-induced cracking and rust-expansion displacements; (ii) for the same structural configuration, the rust expansion displacements at the crack initiation and full crack propagation of confined structures are greater than those of unconfined structures; and (iii) due to the influence of interfacial effects, the rust expansion displacement values at the two times predicted by the M1 model are always smaller than those obtained using the M2 model, with differences of up to 50.3%.