Resumo em Inglês:

Abstract The study investigates the integration of alternate fine aggregates like Manufactured sand (MS), Crushed Rock Fines (CRF), Eco Sand (ES) into high-performance concrete M75 grade mixes, along with the inclusion of Alccofine 1203 admixture and glass fibers. It explores various replacement levels of the fine aggregates and evaluates the impact of adding Alccofine 1203 and alternate fine aggregates on the concrete performance. Alccofine 1203, a supplementary cementitious material, replaces a part of the binding component in concrete and enhancing the strength and durability properties and also mitigate the alkali-silica reaction. The incorporation of glass fibers improves concrete’s bending and tensile strength. The concrete mixes were carefully designed to meet specific strength and durability requirements. A comprehensive testing regimen assessed both fresh and hardened concrete properties, offering insights into overall quality and performance. This research work found that a high-performance concrete mix with 80% crushed rock fines and 20% eco sand exhibited superior strength and durability. Using crushed rock fines not only increased strength, especially when combined with Alccofine 1203, enhanced the strength and also reduced costs associated with manufactured sand. This combination of alternate fine aggregates in concrete mixes can contribute to sustainable construction practices, cost savings, improved concrete performance and regulatory compliance with environmental standards. Strength properties were validated using the Response Surface Methodology (RSM) Model, which evaluates the relationships between variables and concrete strength characteristics. Comparing measured strengths with the model validated predictions and provided insights into concrete mix performance.

Resumo em Português:

RESUMO Nos processos de conformação de materiais metálicos, como a laminação a frio de aços inoxidáveis, a deformação é induzida pelo movimento relativo entre o material e a ferramenta, resultando em forças de atrito. No entanto, os materiais apresentam comportamentos distintos durante a deformação plástica. Neste estudo, foram conduzidos ensaios de microesclerometria para investigar o efeito de diferentes condições de lubrificação no comportamento tribológico de amostras de aço inoxidável AISI 304 e AISI 430, previamente encruadas por laminação a frio. Os resultados do coeficiente de atrito e da profundidade de penetração dos riscos foram analisados, além do perfil dos riscos ter sido investigado por meio de perfilometria 3D. Nos ensaios de microesclerometria, não foram observadas diferenças significativas no coeficiente de atrito em função da condição de lubrificação para ambos os aços. O coeficiente de atrito do aço AISI 430 foi cerca de 23% maior que o do aço AISI 304, devido ao aumento de rugosidade resultante de sua deformação plástica. A profundidade de penetração foi maior para o aço AISI 304, devido à transformação da austenita metaestável em martensita durante a deformação. A análise do perfil dos riscos por perfilometria revelou que não houve remoção significativa de material, apenas deslocamento de material do sulco para as bordas do risco.

Resumo em Inglês:

ABSTRACT In metallic materials forming process, in general, which includes the cold rolling of stainless steels, deformation is induced by the relative movement between the material and the tool used, resulting in friction forces. However, materials behave differently during plastic deformation. In this study, microsclerometry tests were carried out to investigate the effect of different lubrication conditions on the tribological behavior of AISI 304 and AISI 430 stainless steel samples, previously hardened via cold rolling. The results of the friction coefficient and the depth of penetration of the scratches were analyzed, in addition to the scratch profile being investigated using 3D profilometry. In the microsclerometry tests, no significant differences were observed in the coefficient of friction as a function of the lubrication condition used for both steels. The coefficient of friction of the AISI 430 steel was around 23% higher than that of the AISI 304 steel due to the increase in roughness due to plastic deformation of the AISI 430 steel. The penetration depth was higher for AISI 304 steel due to the transformation of metastable austenite into martensite by deformation. Analysis of the profile of the scratches via profilometry revealed that there was no significant material removal, only displacement from the groove to the edges of the scratch.

Resumo em Inglês:

ABSTRACT Triply periodic minimal surface (TPMS) structures are commonly used for lightweight and energy-absorption applications. TPMS structures have a high porosity and are prone to the pinch-off phenomenon. In this study, we designed primitive and Schoen I-graph-wrapped package (I-WP) structures with different porosities. An optimized design function was introduced to obtain a high-porosity P-I structure, which was less prone to pinch off. The mechanical properties of the structures with different porosities achieved using selective laser sintering technology were investigated. Results showed that the porosities of primitive, I-WP, and P-I structures exhibited different correlations with the constant t. The elastic modulus and yield strength of all three structures decreased with porosity. For the same porosity, the compressive strength and elastic modulus of the P-I porous structure exceeded those of the primitive and I-WP porous structures. Additionally, the primitive porous structure was predominantly in the stretching deformation mode, whereas the I-WP and P-I structures were mostly in the stretching and bending deformation modes. The P-I porous structure showed better energy-absorption properties than the primitive and I-WP structures. This study enriched extremely small-surface porous structures and provided a relevant basis for their application in engineering fields.

Resumo em Inglês:

ABSTRACT The study aims to enhance the mechanical properties of AA2124 aluminum alloy matrix composites reinforced with silicon nitride (Si3N4) particulates, utilizing powder metallurgy and high-energy ball milling techniques. Reinforcing metal matrices with ceramic particulates like Si3N4 offers potential strength, hardness, and thermal stability improvements for advanced engineering applications. AA2124 alloy powder was mixed with Si3N4 particulates (5-20 wt%) and milled for varying durations to achieve uniform dispersion. The mixtures were compacted and sintered at 500°C in an argon atmosphere. Microstructural characterization was performed using SEM, XRD, and particle size analysis. Mechanical properties were evaluated through tensile, fatigue, and creep tests, along with microhardness measurements. The composites exhibited significant improvements in mechanical properties, with optimal results observed at 15 wt% Si3N4 and 60 minutes of milling. The tensile strength increased to 475 MPa from 320 MPa, and microhardness reached 297 kgf/mm2 compared to 37 kgf/mm2 for the unreinforced alloy. Enhanced fatigue life and creep resistance were also noted. This study demonstrates that optimizing Si3N4 content and milling duration can significantly enhance the mechanical properties of AA2124 composites, making them suitable for aerospace and other high-performance applications. The findings provide a basis for developing advanced aluminum matrix composites with superior mechanical properties.

Resumo em Inglês:

ABSTRACT This study investigates the feasibility of using concrete reinforced with a blend of coir and bamboo as a sustainable building material. Bamboo, known for its robust yet lightweight nature, serves as a natural reinforcement with high tensile strength, enhancing structural properties. Various lengths and diameters of bamboo reinforcements are coated with gloss enamel and black coal tar for durability is employed in this study. Coir is sourced from coconut husks and recognized for its strength and resilience in composite construction. The research explores the combined action of coir rope fibers and bamboo to improve tensile strength, flexural strength, and durability in concrete slabs. Twelve slabs are examined with featuring of conventional reinforcements, dried bamboo, gloss enamel-painted bamboo and black coal tar-coated bamboo with different diameters. The mechanical properties of concrete specimens are subjected to compressive force test according to IS 456:2000. While steel-reinforced slabs exhibit superior strength, it is noteworthy that 1.75% of black coal tar-coated bamboo reinforcement with coir rope performs comparably to traditional steel reinforcement in conventional concrete.

Resumo em Inglês:

ABSTRACT This research deals with the study of the various factors affecting the performance of circular shaped elevated water tanks made of reinforced concrete material with framed staging with filled as well as empty conditions due to past Indian earthquakes. Six ground accelerations have been picked out based on the strong motion parameters. Eight numbers of existing tanks have been selected with different storage capacity and structural configurations. Seismic performances such as base shear, base moment and hydrodynamic pressure are calculated using Response Spectrum method for the ground accelerations selected. The results due to all the ground accelerations are compared with that obtained by the elastic design response spectrum available in IS1893: part1 (2016). Eventually, it has been found out that the performances of each tank for every acceleration is highly influenced by the structural configuration, mainly for empty tanks. Hence, this research is intended to achieve desirable performances of water tanks during the occurrences of earthquakes by providing appropriate number of columns and horizontal bracing configuration. To ensure this, an experimental investigation has also been done on two models, tank 1 of capacity 105.86 m3 and tank 2 of 223.278 m3, to determine the dynamic properties of tanks.

Resumo em Inglês:

ABSTRACT Several research studies have been conducted on bitumen modification using solid waste materials. However, since textile waste contributes significantly to the formation of solid waste, more research is required on bitumen modification using textile waste. This study tried to modify bitumen using Textile Pyrolysis Oil (TXPO) and test its ageing properties. Pyrolysis oil was made by pyrolysing textile waste at 500°C. Textile Pyrolysis Oil Modified Bitumen (TXPOMB) was made by adding 1, 2 and 3% TXPO by weight of the Viscosity Grade 30 (VG30) bitumen and mixing in a high shear mixer. The binders are subjected to short-term ageing using a rolling thin film oven and long-term ageing using a pressure ageing vessel test in the laboratory. The effect of adding TXPO to a base binder and their oxidation process were investigated using Fourier Transform Infrared (FTIR) Spectroscopy. Chemical indices such as aromatic, aliphatic, carbonyl, and sulfoxide indices are calculated from FTIR spectroscopy to evaluate the effect of ageing. It was seen that 2% TXPO modification enhances the base binder’s ageing resistance in both short and long-term ageing conditions. This modification not only addresses environmental concerns but also improves the performance and longevity of the bituminous materials.

Resumo em Inglês:

ABSTRACT Additive manufacturing opens new possibilities for new designs and manufacture of architected metamaterials and nanocomposites. Among the 3D printing technology, vat polymerization is highlighted due its higher resolution, smother surface and printing speed. In spite of the growing interest in the Additive Manufacturing technologies and the potential benefits of graphene reinforcement to improve the properties of parts produced by vat polymerization-based 3D Printing; there is a lack in understanding of the effects of adding graphene to photosensitive vat resin. Therefore, in this study the effect of adding graphene (0.3 and 0.5%) on the chemical, thermal and mechanical properties of parts fabricated by vat polymerization of a standard photosensitive acrylic resin was determined. Graphene addition resulted in a minimal modification of polymeric structure; however, it had a significant impact in the UV curing. The addition of graphene nanoplatelets hindered the photopolymerization of standard acrylic resin as consequence a higher amount of unpolymerized monomers are found after printing. Regarding the mechanical properties, graphene addition promoted a slight improvement in the Elastic Modulus while decreased tensile and flexural strength and it had no significative impact in toughness. An additional thermal curing step can be an alternative to improve polymerization and mechanical strength. These findings contribute to a deeper understanding of the effects of adding graphene to vat polymerization and its potential and limitations.

Resumo em Inglês:

ABSTRACT Because of its better strength-to-weight ratio, moldability, fracture resistance, and ability to employ local materials, ferrocement is becoming a more and more popular building material. An environmentally friendly substitute is provided by geopolymer technology, which uses alkali solutions to activate materials high in silica and alumina. This study focuses on geopolymer-based ferrocement slabs, exploring their flexural properties and substituting geopolymer mortar for cement to enhance performance. This study investigates the effects of varying percentages of fly ash (ranging from 0% to 20%), GGBS (ranging from 80% to 100%), and 2% of nano silica on the properties of ferrocement geopolymer concrete. Flexural behavior are tested using Carbon Fiber Reinforced Polymer (CFRP) wound wire mesh. Fly ash, a coal plant byproduct, is combined with GGBS to improve strength and setting. A 1:2 mortar ratio, containing sodium silicate, sodium hydroxide, GGBS and fly ash, is utilized. Optimal results are achieved with 80% GGBS addition, despite higher strength observed with 100% GGBS in fly ash. Nano silica further enhances performance, with a significant 240% strength increase observed with 1.5% nano silica and 80% GGBS. The study concludes by identifying superior combinations for practical application, considering specimen permeability, acid resistance, and heat resistance.

Resumo em Inglês:

ABSTRACT Lightweight materials are the great demand in the aerospace sector to enhance system performance. The automotive, aerospace sector has utilized the composite materials to strengthen the physical and mechanical qualities of less weight materials and to improve their functionality. In this study, three different base matrix alloy combinations comprise the specimens being examined. Selective laser melting was used to combine boron carbide, graphite, and iron oxide powder (2.5, 5 and 7.5 wt.%) with an aluminium alloy matrix. Use the ASTM B-557M standards, specimens are prepared for testing the hybrid composite including such wear, and scanning electron microscopy. The purpose of the current study is to use Taguchi-based gray relational analysis (TGRA) to improve the wear parameters of aluminium matrix composite. Grey relationship study has shown that the optimal combinations for determining the hybrid composite’s wear rate and coefficient of friction are 40 N load (level 3), 6 m/s sliding speed (level 3), and 1000 m sliding distance (level 1). Hybrid composites are said to have better wear properties and to offer enhanced components for the automotive, marine, and aerospace industries as compared to earlier metal matrix composites.

Resumo em Inglês:

ABSTRACT This study explores the enhanced performance of nano-silica-enriched concrete beams, with a focus on the effects of including steel fibers. A thorough examination was conducted on eighteen finely constructed beams, each three thousand millimeters long and with a 150 × 250 millimeter cross-section. This study’s main goal was to evaluate how steel fibers affected these beams’ mechanical characteristics. A number of static loading tests were used to carefully examine the specimens’ structural strength. The overall effectiveness of the concrete beams was assessed by carefully using key parameters as indicators, such as the first crack load, yield load, yield load deflection, ultimate load deflection, deflection ductility, deflection ductility ratio, energy ductility, and energy ductility ratio. The findings of the extensive testing clearly show that adding steel fibers to concrete beams that contain nano silica improves their performance significantly. This enhancement was regularly seen in a number of important areas of structural behavior, proving without a shadow of a doubt the beneficial effect of steel fiber incorporation on the beams’ mechanical characteristics.

Resumo em Inglês:

ABSTRACT Prolonged loading can lead to concrete cracking due to its weak tensile strength, impacting both durability and load-bearing capacity, especially when reinforcing bars corrode. This study investigates the efficacy of microbial-based self-healing in enhancing the performance of high-strength concrete, specifically targeting Bacillus Pasteurii and Bacillus Flexus. The findings indicate significant improvements in both micro- and macro-properties of high-strength bacterial concrete treated with these strains, surpassing control samples. Concrete infused with Bacillus Flexus exhibits a notable increase of 23.75% in compressive strength at 7 days and 12.36% at 28 days, with similar enhancements observed in Flexus-treated concrete. The presence of calcite precipitation, confirmed by X-ray diffraction and scanning electron microscopy, contributes to crack healing, achieving closure within 56 days. Microbial concrete from these strains demonstrates superior durability against water, acid, and salt exposure, suggesting the potential of microbial-based self-healing to fortify structural resilience and extend the lifespan of concrete infrastructure.

Resumo em Inglês:

ABSTRACT An ultrasonic treatment was used to ensure that the nano zinc oxide abbreviated ZnO, was uniformly dispersed throughout the cement paste mixture with addition of fly ash, replacing 10% of the weight of cement. The characteristics of the cementitious mixture were investigated in this research work. The experimental work was carried out by adding nano-ZnO in increments of 0%, 0.25%, 0.5%, 0.75% and 1% by weight of cement, resulting in changes in the characteristics of the concrete paste. The quantity of nano-ZnO present in the cementitious mixture had a notable influence on the consistency of the cement. This impact was also found when the cement paste contained only 0.5% cement by weight. The electrical resistance studies found that the inclusion of nano-sized particles can both delay the hydration of blended cement mix and increase the hydration rate. The findings of experiments revealed that increasing the nano-ZnO concentrations in the cement paste resulted in greater long-term strength. Furthermore, the pore diameter distribution was optimized by the inclusion of nano-ZnO and a tight microstructure was formed in the cementitious mixture at 28 days.

Resumo em Inglês:

ABSTRACT The disposal of untreated effluents and the lack of efficient and effective treatment have raised concerns. In this sense, methylene blue dye is classified as a priority contaminant among the dyes released into industrial effluents. It is used in several segments, such as dyeing cotton, silk, paper, paints, among others. In this context, the use of bioadsorbents obtained from food waste to remove methylene blue dye would be a viable alternative, as it allows the use of waste generated in large quantities and at low cost, in addition to being an environmentally friendly alternative. Totally correct and sustainable. Therefore, the main objective of this work was to study the use of food waste as bioadsorbents in the removal of methylene blue dye. To achieve this, bio-adsorbents were produced from food waste, such as chicken eggshells, passion fruit peels and orange peels, in natura, thermally activated and chemically activated. The characterization of the bioadsorbents produced was carried out through analyzes of specific surface area, thermal behavior, morphology and structure, in addition to determining yield. The performance of the bioadsorbents was comparatively evaluated in the batch adsorption process to remove the methylene blue dye. The adsorption tests showed that the bioadsorbents developed were efficient in removing the dye, showing removal of more than 64%. The samples that obtained the best results were passion fruit peel, with thermal (MT) and chemical (MQ) treatment, and orange, with chemical treatment (LQ), achieving dye removals greater than 98%, due to their high specific surface areas. It was not possible to obtain adsorption isotherms for samples MQ and LQ, due to the high percentages of dye removal achieved, even for the different initial concentrations studied.

Resumo em Inglês:

ABSTRACT This study investigates the properties of self-consolidating green concrete (SCGC) through experimental tests and employs artificial intelligence techniques for design parameter analysis. Cement is partially substituted with granulated blast furnace slag (GBFS) powder, volcanic powder, fly ash, and micro-silica. Fresh and hardened properties tests are conducted. An adaptive neuro-fuzzy inference system (ANFIS) is developed to identify parameters influencing compressive strength. Seven ANFIS models evaluate input parameters individually, while twenty-one models assess different input combinations for optimization. Furnace slag significantly impacts hardened properties in binary mixes, while volcanic powder enhances slump retention. Ternary mix design with micro-silica and volcanic powder demonstrates substantial improvement. ANFIS results highlight binder content as the primary governing parameter for SCGC strength. The combination of micro-silica and volcanic powder exhibits superior strength compared to other additives, confirmed by test results. Overall, the study underscores the efficacy of incorporating micro-silica and volcanic powder for enhancing SCGC strength and sustainability.

Resumo em Inglês:

ABSTRACT Currently, fully encased composite columns (FECCs) and high-strength concrete (HSC) are widely used in the construction industry to build durable structures. Specifically, HSC is primarily employed in high-rise buildings, highway bridges, and tunnels. This study examined eight FECC specimens with 200 mm × 250 mm × 1000 mm dimensions. Four FEC columns were considered control specimens, while the remaining four were cast with the optimum content of 0.60% Steel Fibre (SF). These specimens were fabricated with two different lateral reinforcement spacing: 100 mm and 80 mm. All specimens were tested under axial loading using a 500 T capacity frame. The main objective of this study was to evaluate the axial load-carrying capacity, axial load-deformation behaviour, ductility, stiffness, energy absorption capacity, and mode of failure of all FECC specimens. Adding 0.6% steel fibre and reduced lateral reinforcement spacing enhanced the specimens axial load-carrying capacity, ductility, and energy absorption capacity. The steel fibre was crucial in preventing concrete cover spalling and cracks on the specimens. Experimental test results for the FECC specimens were compared to various codes, including IS: 456 – 2000, JGJ 138-2016, and EN 1994-1-1. The present results were compared to previously published data and evaluated using the same codes. According to the experimental and analytical findings, the prediction results from JGJ 138-2016 and EN 1994-1-1 were highly correlated with the experimental results. EN 1994-1-1 is recommended for developing two proposed methods, which were also compared to the experimental test results. These proposed methods demonstrated good agreement with the experimental outcomes, with mean values of 1.08 and 1.06, standard deviations of 0.04, and coefficients of variation of 3.54% and 3.53% for proposed methods 1 and 2, respectively.

Resumo em Inglês:

ABSTRACT The current investigation concentrates on evaluating the performance of inhibitors added to concrete to resist corrosion. Specimens were cast with different mix proportions involving various combinations of inhibitors of M30 grade prepared as per Indian standards. For investigating the performance of inhibitors added in the concrete of M30 grade various tests such as pH measurement, Weight loss measurement, OCP otherwise known as rest potential measurement, impressed voltage, Rapid Chloride Penetration test and determination of chloride diffusion coefficient were conducted. To evaluate the strength parameters tests were conducted on the casted specimens of concrete. The tests include compression strength test, flexural and strength test. Results indicated that amine compound-based inhibitor has a more pore-clogging impact which blocks chloride ingress. The polarization and impedance behavior of steel in concrete after the electrochemical injection process exhibited a considerable reduction in the occurrence of the rate of corrosion in steel reinforcement despite the severe chloride ions. IR spectra observations recorded the existence of inhibitor molecules on the embedded steel surface.

Resumo em Inglês:

ABSTRACT This research examines the effectiveness of cellulose nanofibers (CNFs) in reinforcing beam-column joints against repeated, reversed stresses (cyclic loading), a crucial factor in earthquake resistance. By exploring various combinations of silica fume and CNF content, the study aimed to develop a high-performance concrete mix. The hypothesis centered on enhancing joint ductility, the ability to absorb energy, through the combined effect of CNFs with varying lengths and volumes alongside silica fume. The results were remarkably positive. When CNFs were incorporated, the joints exhibited significant improvements in multiple areas: deformability (capacity to deform under stress), ductility (energy absorption), and overall ability to dissipate energy during cyclic loading. Furthermore, the CNFs led to a reduction and better distribution of cracks within the joints, while also increasing the load required for initial cracking and the overall load-bearing capacity. These findings highlight the promise of cellulose nanofibers as a reinforcement material for beam-column joints in earthquake-prone structures. Further research can optimize their use with silica fume for broader adoption in sustainable and resilient construction practices.

Resumo em Inglês:

ABSTRACT Autoclaved Aerated Concrete (AAC) developed with Coconut Shell Charcoal (CSC) powder is a newly developed concrete with reasonable compressive strength and durability properties. The main idea of this study is to find out the applicability of CSC powder as partial replacement for fine aggregate in AAC, and the role of CSC in obtaining the strength and durability of AAC are discussed. In this study, material selection is done with reference to ASTM C1693-11 and CSC was used as a replacement material for river sand. CSC is an agricultural waste. Since the SiO2 content of CSC is very low, Silica Fume (SF) is also used as fine aggregate replacement in addition to CSC to enhance the SiO2 content. The specimens were made combining CSC and SF powders; CSC at 0%, 5%, 10%, 15% and 20% and SF at 0%, 1%, 2%, 3% and 4% by weight, and are coded as B0, B5, B10, B15 and B20 respectively. The developed AAC was analysed by conducting compressive strength, bulk density, thermal conductivity, scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses. Additionally, water absorption, porosity, ultrasonic pulse velocity and acid attack tests were performed to determine the durability. XRD analysis showed the traces of C-S-H (Calcium Silicate Hydrate) gel and tobermorite peaks in B5 specimen, which produced enhanced compressive strength of 3.12 N/mm2. Thermal conductivity of the specimen with CSC replacement was between 0.218 to 0.186 W/m-K; it could be remarked from the results that the developed AAC is good in thermal insulation. Even though the porosity level reduced to 2% in B20 replacement, the specimens were light in weight, compared to B0. From the results obtained, it could be drawn the inference that CSC is a potential replacement for fine aggregate in AAC.

Resumo em Inglês:

ABSTRACT The Metal Injection Molding (MIM) process is used for small parts, complex geometries, and high production volumes. Among the various ferrous and non-ferrous alloys that use this technology, the precipitation-hardened stainless steel Catamold 17 - 4 PH stands out. This class of steel used in the aerospace and automotive industries is characterized by its resistance to corrosion combined with excellent mechanical properties. The sintering process of this steel is carried out in a controlled hydrogen-based atmosphere, which, together with the raw material, impacts the manufacturing cost of the components. In this work, different sintering atmospheres were evaluated, and the effects were verified using optical microscopy, scanning electron microscopy (SEM), the EDS microprobe, microhardness, and potentiodynamic polarization techniques. The results demonstrated that the microstructure and microhardness of the substrate were not affected. However, deleterious effects were detected with an increase in the level of porosity, compromising the corrosion resistance of the analyzed samples. Comparatively, samples with pure nitrogen showed better corrosion resistance compared to those with the presence of water vapor. However, it was less resistant to corrosion than found in the literature in a hydrogen atmosphere, considered the state of the art for Catamold 17 - 4 PH stainless steel.

Resumo em Inglês:

ABSTRACT Ni-Cr brazing filler metal containing varying amounts (0 wt%, 3 wt%, and 5 wt%) of nickel-coated graphite (Ni/C) was employed to prepare brazed synthetic diamond samples. The interfacial microstructure characterization and thermal damage of brazed synthetic diamond were investigated using scanning electron microscope and Raman spectroscopy. The mechanical properties of static pressure strength and impact toughness of brazed synthetic diamond were investigated in accordance with the machinery industry standard. The hardness of brazed layer was measured using a micro-hardness tester. The results demonstrate the presence of lamellar compounds Cr3C2 and void columnar compounds Cr7C3, as well as filamentous eutectic graphite, on the surface of brazed synthetic diamond following aqua regia corrosion. Increasing the Ni/C ratio in the Ni-Cr brazing filler metal leads to a reduction in graphitization degree of synthetic diamond. When the Ni-Cr brazing filler metal contains 5 wt% Ni/C, the compressive stress in brazed synthetic diamond is reduced by 65 MPa, the static pressure strength and impact toughness of brazed synthetic diamond are increased by 15.1% and 29.9%, respectively, and the hardness of brazed layer is decreased by 79 HV, this is beneficial to enhance self-sharpness of synthetic diamond tools brazed with Ni-Cr brazing filler metal.

Resumo em Inglês:

ABSTRACT Illicit drug abuse to enhance athletic performance undermine integrity of sports. Detecting banned substances is challenging owing to rapid clearance and evasion via masking agents. Chromatography techniques are constrained by cost, analysis times and portability impeding on-site testing. Electroanalytical sensors incorporating carbon nanomaterials demonstrate vast promise as rapid, sensitive and cost-effective complementary screening tools. Exceptional conductivity, electrocatalysis and functionalization potential of graphene, carbon nanotubes and fullerenes allow parts-per-billion detection limits matching immunological assays for stimulants and anabolics. Aptamer integration also imparts target specificity. Nevertheless, translation from lab prototypes to commercial devices needs optimization of green synthesis protocols and surface stabilization for reliable reproducibility. Coupling to microfluidics and machine learning data harmonization can enable automated sampling, multi-marker testing and wireless result archiving at decentralized point-of-care. Overall, miniaturized nanosensors adequately sensitive for divide cutoff concentrations aid anti-doping enforcement through early interventions, chelation therapy and deterrence against proliferation of doping culture among athletes.

Resumo em Inglês:

ABSTRACT This study examines into optimizing the composition of dispersed cement systems to reduce inter-particle voids, thereby enhancing solidity and density. The investigated concrete mixtures contain micro silica, granular blast furnace slag that has been finely dispersed, superplasticizer Glenium 430, high-valence hardening accelerator, and two fine aggregate fractions: 10–15 mm granite crushed stone and Portland cement grade 53. Laser analysis was used to analyze the size and shape of the particles, and the structure of the cement block was investigated using X-ray phase analysis, thermographic analysis, and scanning microscopy. The optimized concrete’s compressive strength was evaluated at five and twenty-eight days; the results showed values of 52–74 MPa and 128–163 MPa, respectively, at cement utilization levels of 650–750 kg/m3. It was shown that the use of a bimodal clinker component and granulated blast-furnace slag blend was effective. Furthermore, there is empirical data suggesting confirms the optimal amounts of nanoscale additions, such as micro silica, required to get the most favorable outcomes.

Resumo em Português:

RESUMO A compreensão dos efeitos da microcelulose cristalina em argamassas de revestimento é essencial para projetar materiais mais duráveis, resistentes e eficientes na construção. Dessa forma, o presente trabalho tem por finalidade verificar a influência da adição de teores de 0,2%, 0,4% e 0,6% de microcelulose cristalina (MCC) em relação à massa do cimento nas propriedades no estado fresco e endurecido de argamassas de revestimento. O estudo foi desenvolvido considerando o impacto das adições de microcelulose nas argamassas de revestimento através da consistência, por meio do ensaio flow-table, da densidade de massa, do teor de ar incorporado e do comportamento reológico através do ensaio de squeeze-flow, como também resistência à compressão e à tração na flexão e o módulo de elasticidade dinâmico. Com base nos resultados obtidos, foi possível concluir que a incorporação de microcelulose cristalina resultou na diminuição da consistência das argamassas. Nas concentrações de 0,2% e 0,4% houve um aumento na incorporação de ar, na plasticidade em quinze minutos da mistura e na redução da densidade de massa, indicando que esses percentuais podem atuar melhorando o processo de aplicação, facilitando a execução das argamassas de revestimento. Contudo, após trinta minutos de mistura, foi possível observar uma mudança no comportamento reológico, onde as argamassas com adição de microcelulose cristalina apresentaram uma redução nos deslocamentos em relação à referência, indicando que a alta capacidade de retenção de água da microcelulose cristalina pode influenciar na plasticidade das argamassas ao longo do tempo da mistura. No estado endurecido, foi possível concluir que as adições de microcelulose cristalina de 0,2% e 0,4% não resultaram em melhorias nas propriedades das argamassas de revestimento.

Resumo em Inglês:

ABSTRACT Understanding the effects of crystalline microcellulose in rendering mortars is essential for designing more durable, resistant, and efficient construction materials. Therefore, this study aims to verify the influence of adding 0.2%, 0.4%, and 0.6% of crystalline microcellulose (MCC) relative to the cement mass on the fresh and hardened properties of rendering mortars. The study was developed considering the impact of microcellulose additions on the rendering mortars through consistency, (using the flow-table test), bulk density, incorporated air content, and rheological (using the squeeze-flow test), as well as compressive and flexural tensile strength, and dynamic modulus of elasticity. Based on the results obtained, it was concluded that the incorporation of crystalline microcellulose resulted in the consistency of the mortars. At concentrations of 0.2% and 0.4%, there was an increase in air incorporation, plasticity after fifteen minutes of mixing, and a reduction in bulk density, indicating that these percentages may improve the application process, facilitating the execution of rendering mortars. However, after thirty minutes of mixing, a change in rheological behavior was observed, where mortars with crystalline microcelulose addition showed a reduction in displacements compared to the reference, indicating that the high water retention capacity of crystalline microcellulose may influence the plasticity of the mortars over the mixing time. In the hardened state, it was concluded that additions of crystalline microcellulose did not result in improvements in the properties of rendering mortars.

Resumo em Inglês:

ABSTRACT The extensive use of cement has caused significant resource consumption and serious carbon emission problems. Recycling steel slag to partially replace cement presents a promising alternative. This study utilized steel slag powder (SSP) and steel slag aggregate (SSA) to prepare cement stabilized aggregate (CSA). The effects of different amounts of SSP and SSA on the road performance of CSA were studied, which was also compared with cement-fly ash (FA) stabilized aggregate (CFSA). The results demonstrated that adding SSP and SSA resulted in higher optimal moisture content and the maximum dry density of CSA. Adding 10% SSP enhances the mechanical properties of CSA. Compared to FA, SSP shows superior improvement effects at a 30% substitution rate. The dry shrinkage coefficient of CSA decreases as the SSP content increases. Further addition of SSA can further reduce shrinkage of CSA. The proper amount of SSP has no obvious effect on cement hydration, and the hydration degree of cement-SSP was higher than that of cement-FA. In addition, the higher the SSP blend, the lower the cost of the CSA and the lower the carbon emissions. Taking into account the performance, environmental impact, and cost of CSA, the optimal admixture of SSP is 30%.

Resumo em Inglês:

ABSTRACT In this study, a flexible capacitive pressure sensor was developed, featuring a dielectric layer composed of a polydimethylsilane (PDMS)/BaTiO3/SrTiO3 composite material. The electrode and dielectric layers were structured with a dual microstructure, combining diagonal and sandpaper-porous elements. Additionally, nano-barium titanate (BT) powder, known for its relatively high dielectric constant, was incorporated into PDMS, along with an appropriate amount of strontium titanate (STO), to enhance the sensor’s sensitivity. The developed sensor exhibited a remarkable sensitivity of 2.681 kPa–1, with response and release times of approximately 39 ms and 61 ms, respectively. It demonstrated a low detection threshold and withstood over 5000 compression cycles, showcasing excellent repeatability. The results underscored the sensor’s robust pressure-sensing performance, making it suitable for diverse applications, including human pulse monitoring, heartbeat tracking, robot arm sensing, object weight detection, and real-time healthcare monitoring.

Resumo em Inglês:

ABSTRACT Textile reinforced concrete (TRC) is an innovative technology increasingly utilized for various applications involving thin concrete composite panels. This experimental study investigates the use of fly ash as a supplementary cementitious material in the production of cementitious mortar, enhanced by the addition of 20% silica fume by weight of cement to improve compressive strength. The research incorporates fibers of Polyvinyl Alcohol (PVA), basalt, and polyester with varying volume fractions into the composites to mitigate cracking in the concrete. Additionally, Alkali-Resistant glass fiber mesh was integrated into the cementitious composites in varying layers to create thin TRC laminates. Specimens were cast and tested to determine their compressive, tensile, and flexural strengths. The study identified the optimal fiber volume fraction for hybrid fibers, with PVA fiber at 2% demonstrating superior performance due to its excellent tensile strength and high modulus of elasticity, making it the reference mix. Hybridization with basalt and polyester fibers at different volume fractions was also explored. Results indicated that increasing fiber content and the number of layers significantly enhanced the strength, toughness, and energy absorption of the composite elements. Increasing of fiber volume fraction in terms of mesh, give much improvement in the matrix.

Resumo em Português:

RESUMO A fabricação e o envase de vacinas tornaram-se primordiais no cenário mundial em função do ressurgimento da pandemia da COVID-19 desde 2020. O processo de obtenção da vacina vai desde estudos laboratoriais até o seu armazenamento em tanques reservatórios de produto. Para tanto, a vacina passa por bombas de envase e mangueiras sanitárias, até o envase efetivo nos frascos e ampolas por meio de agulhas de envase. No entanto, as mesmas são desenvolvidas em aço inoxidável 316L, que quando exposto a líquidos estagnados ou em movimento podem corroer e contaminar o fármaco. Nesse contexto, esse trabalho tem como objetivo avaliar se existe contaminação química das agulhas fornecidas pela Empresa Teksul Soluções em Envase. Para tanto, 21 agulhas de envase foram imersas em excipientes, com propriedades físico-químicas que se equivalem à vacina, durante 0, 35, 63 e 94 dias. Os excipientes foram avaliados quanto ao pH e por absorção atômica, enquanto as agulhas foram avaliadas por análise de perda e ganho de massa, análises microscópicas obtidas ao MEV (Microscópio Eletrônico de Varredura) e testes eletroquímicos de corrosão. Os resultados mostraram que o aumento do tempo de imersão das agulhas de envase favoreceu a formação de uma camada passiva com propriedades de resistência à corrosão.

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ABSTRACT The manufacturing and packaging of vaccines have become essential on the global stage due to the resurgence of the COVID-19 pandemic since 2020. The process of obtaining the vaccine ranges from laboratory studies to its storage in product reservoir tanks. To do so, the vaccine passes through filling pumps and sanitary hoses, until it is effectively filled into vials and ampoules using filling needles. However, they are developed in 316L stainless steel, which when exposed to stagnant or moving liquids can corrode and contaminate the drug. In this context, this work aims to evaluate whether there is chemical contamination of the needles supplied by the company Teksul Soluções em Envase. To this end, 21 filling needles were immersed in excipients, with physicochemical properties that are equivalent to the vaccine, for 0, 35, 63 and 94 days. The excipients were evaluated for pH and atomic absorption, while the needles were evaluated by mass loss and gain analysis, microscopic analyzes obtained using SEM (Scanning Electron Microscope) and electrochemical corrosion tests. The results showed that increasing the immersion time of the filling needles favored the formation of a passive layer with corrosion resistance properties.

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ABSTRACT In the face of environmental challenges stemming from the accumulation of waste glass and cement production, significant contributors to CO2 emissions, this study explores sustainable construction alternatives by incorporating waste glass (WG) and metakaolin (MK) as partial cement substitutes. Experimental Various concrete mixes containing different percentages of WG and MK (10%, 20%, 30% for WG, and 15% for MK) were evaluated against a standard reference mix. Analyses focused on workability, compressive strength, water absorption, electrical resistivity, ultrasonic pulse velocity (UPV), and chloride ion penetration. The results showed that mixes with 20WG and 30WG enhanced fluidity by 16.67%. In the hardened state, mixes with 10WG and 15MK recorded compressive strength increases of 31.5% and 25.97% at 91 days, respectively. Further tests on electrical resistivity, UPV, and chloride ion penetration indicated that WG and MK contribute to a denser and less porous concrete microstructure, improving durability against chloride ingress. Additionally, water absorption did not increase proportionally with strength, suggesting that other factors beyond porosity influence strength. These findings support the use of glass waste and metakaolin in concrete production to promote more sustainable building practices and extend the lifespan of concrete structures.

Resumo em Inglês:

ABSTRACT An investigation into the use of metakaolin (MK) and fly ash (FA) as partial cement replacements in concrete was conducted to enhance the sustainability of the construction industry. The MK and FA were incorporated into the concrete mix design by weight, replacing a portion of the portland cement content. The replacement percentages varied in two sets: 5%, 7.5%, 10%, 12.5%, and 15% for MK; and 5%, 10%, 15%, 20%, and 25% for FA. Workability of the fresh concrete was evaluated using the slump cone test to identify the optimal replacement level. Subsequently, the mechanical properties of the hardened concrete were investigated using compressive strength (CS), split tensile strength (STS), flexural strength (FS), modulus of elasticity (MoE). The results revealed that incorporating MK improved the mechanical properties: CS increased by 12.06%, STS by 16.84%, and FS by 15.42% compared to the control mix. In comparison, FA substitution resulted in a slightly lower increase: CS by 9.72%, STS by 12.84%, and FS by 8.57%. The study concluded that MK exhibited a superior performance in enhancing the strength properties of concrete compared to FA. Additionally, linear regression analysis was employed to establish correlations between the experimentally determined strength properties and the mix design parameters. This analysis demonstrated a strong correlation between the predicted and experimental values, making it a valuable tool for future concrete mix design optimization.

Resumo em Inglês:

ABSTRACT This study aimed to investigate the influence of nanoceramic addition on the performance of cement-based materials, including mortars and concretes. Nanoceramics, a type of nano clay derived from montmorillonite, can potentially enhance the properties of cement-based materials due to their pozzolanic activity. Nanoceramics were added to mortars and concretes at varying percentages (0%, 2%, 4%, 6%, and 8% by weight of cement). Pozzolanic activity tests, workability assessments, compressive strength tests, tensile strength tests, and water permeability tests were conducted on the prepared specimens. The addition of nanoceramics improved the compressive and tensile strengths of mortars and concretes, with optimal percentages varying based on the water-cement ratio. Nanoceramics acted as a pozzolanic material and filler, reducing porosity and enhancing strength. However, higher nanoceramic percentages led to workability issues, necessitating the use of plasticizers or superplasticizers. The study demonstrated the potential of nanoceramics as a mineral admixture for enhancing the performance of cement-based materials. Optimal nanoceramic addition percentages were determined for different water-cement ratios, considering strength gains and workability concerns.

Resumo em Inglês:

ABSTRACT This study aimed to enhance the mechanical, thermal, and biocompatibility properties of polycaprolactone (PCL) nanocomposite nanofibers by incorporating graphene and graphene oxide (GO) using the electrospinning technique. PCL nanocomposite nanofibers were synthesized with varying concentrations of graphene (0.5%, 1%, and 1.5%) and GO (0.5%, 1%, and 1.5%). Mechanical properties were evaluated through tensile strength tests, showing significant enhancements. Graphene increased tensile strength by 10%, 20%, and 30%, while GO improved it by 15%, 25%, and 35% for respective concentrations. Thermal stability was assessed via thermogravimetric analysis (TGA), revealing that the onset degradation temperature increased by 5%, 10%, and 15% for graphene and by 7%, 12%, and 18% for GO. The maximum weight loss temperature improved by up to 20% for GO-reinforced nanocomposites. Results indicated that graphene enhanced cell viability by 8%, 12%, and 15%, and GO by 10%, 15%, and 20%. The thermal stability and biocompatibility improvements were attributed to the better dispersion and stronger interfacial bonding of GO within the PCL matrix. GO-reinforced nanocomposites showed a 20% improvement in cell viability, suggesting their suitability for biomedical applications. These findings indicate that incorporating graphene and GO significantly enhances the properties of PCL nanocomposites, making them suitable for demanding biomedical applications.

Resumo em Inglês:

ABSTRACT Bio-composite materials are gaining momentum as eco-friendly substitutes for synthetic fiber-reinforced composites across various sectors. This study investigates how varying fine powder loads affect the tensile, transverse, and compressive properties of hybrid composites comprising Malabar Ironwood sawdust and COCO dust particles. A hybrid composite formulation was devised using a 1:1 ratio of sawdust and COCO dust particles as fillers. Different levels of reinforcement, ranging from 20% to 60%, were examined. ASTM testing was performed on the produced composites, revealing a notable influence of filler reinforcement on their mechanical characteristics. The elongation at fracture increased until 40% filler loading before declining, whereas tensile strength, transverse rupture strength, transverse modulus, and compressive strength consistently improved up to 50% filler loading. These results underscore the potential of composites integrating Malabar Ironwood, COCO dust, and epoxy for lightweight applications, thereby catering to diverse industries seeking sustainable alternatives to traditional materials. Ultimately, such initiatives contribute to solid waste management efforts, offering sustainable alternatives to conventional materials in diverse industries.

Resumo em Inglês:

ABSTRACT This study aims to optimize the operational parameters of the Bullet plate type flour grinding machine for processing PBW 824 wheat to enhance both machine performance and flour quality. The objective is to identify optimal settings for grinding speed, plate distance, and wheat moisture content using optimization techniques. Response Surface Methodology (RSM) and Central Composite Design (CCD) were employed to evaluate these parameters. Controlled experiments varied each parameter at five levels, collecting data on throughput, energy consumption, flour fineness, and protein content. The results indicate throughput increased from 225–275 kilograms per hour (kg/h) at 900 revolutions per minute (RPM) to 275–400 kg/h at 1500 RPM, while energy consumption rose from 6-10 kilowatt-hours (kWh) to 12–20 kWh. Flour fineness was highest (80%–90%) at smaller plate distances (0.5 millimeters (mm), and protein content decreased from 13%–14.5% at 10% moisture content to 12%–13.5% at 15%. These findings highlight the trade-off between productivity and energy efficiency and the importance of optimizing moisture content to preserve nutritional quality. The study successfully identified optimal operational parameters, enhancing the performance and quality of the grinding machine. Future research could apply these optimization techniques to milling machinery and wheat varieties, contributing to advancements in milling technology and agriculture.

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Abstract Tartrazine (Tz) is a widely used synthetic food colorant that has raised health concerns due to its potential adverse effects. Developing sensitive and reliable methods for Tz detection in food products is crucial for ensuring consumer safety. In this study, Sr-doped ZnO nanoparticles with varying doping levels (0–7 mol%) were synthesized by mechanical milling and applied as an electrochemical sensor for detecting Tz in sports drinks. The ZnO-Sr modified carbon paste electrode (CPE), with an optimal Sr doping level of 5 mol%, exhibited the best sensing performance under optimized conditions of pH 7.0 and an accumulation time of 180 s. The sensor demonstrated a linear range from 1 to 1000 μM, a detection limit of 0.3 μM, and a sensitivity of 0.38 μA/μM for Tz identification. This performance surpasses that of many previously reported electrochemical Tz sensors. The ZnO-Sr modified CPE showed good reproducibility (RSD 3.2%), long-term stability (91.2% current retention after one month), and high selectivity against common interferents. The sensor’s practical applicability was validated by determining Tz in commercial sports drink samples, with results in good agreement with a standard UV-Vis spectrophotometric method (relative errors < 5%). Recovery tests (97.2–103.5%) further confirmed the accuracy and reliability of the proposed sensor. This work presents a simple, sensitive, and reliable approach for monitoring Tz levels in food products, addressing important food safety and human health concerns.

Resumo em Português:

RESUMO O aparecimento precoce de problemas na estrutura dos pavimentos e o não cumprimento do horizonte de projeto não só provocam desconforto aos usuários devido às más condições de rolamento e a falta de segurança durante o tráfego, como também demandam uma maior quantidade de matéria-prima e capital para restauração, recuperação ou reconstrução das estruturas danificadas. Os métodos de dimensionamento de pavimentos flexíveis empíricos-mecanísticos, como o novo método brasileiro de dimensionamento (MeDiNa), consideram o comportamento mecânico das camadas e do pavimento como um todo e representam de maneira mais apropriada a relação existente entre as cargas solicitantes do tráfego e a resposta apresentada pelo pavimento. O MeDiNa faz uso dos parâmetros de rigidez, como o módulo de resiliência (MR), para realizar uma análise elástico-plástica da estrutura. Este parâmetro, por sua vez, sofre algumas limitações de uso, visto que é obtido em laboratório por meio de ensaios triaxiais dinâmicos que exigem a utilização de equipamentos complexos, mão de obra especializada, além de demandar uma quantidade significativa de material e apresentar uma difícil implementação em situações práticas, tornando a execução do ensaio restrita fora das universidades e instituições acadêmicas. Tendo em vista esta problemática, este artigo propõe um modelo neural de regressão para previsão do módulo de resiliência obtido através dos parâmetros geotécnicos básicos e usuais. Ademais, para comprovar a viabilidade do modelo gerado, foram realizadas simulações considerando os diversos tipos de vias, bem como os modelos constitutivos elásticos do solo linear e não-linear. Demonstrando, assim, que se trata de um modelo satisfatório para previsão do módulo de resiliência, que poderá ser empregado tanto em rodovias com volumes de tráfego moderado quanto emvolumes elevados, quando não for possível a realização do ensaio.

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ABSTRACT The early appearance of pathologies in sidewalks and failure to meet the design horizon not only cause discomfort for users due to poor road conditions and lack of safety during traffic, but also demand a greater amount of raw materials and capital for restoration, recovery or reconstruction of damaged structures. Empirical-mechanistic flexible sidewalk design methods, such as the new Brazilian design method (MeDiNa), take into account the mechanical behavior of the layers and the sidewalk as a whole and more appropriately represent the relationship between the traffic loads and the sidewalk’s response. MeDiNa uses stiffness parameters such as the modulus of resilience (MR) to carry out an elastic-plastic analysis of the structure. This parameter, in turn, suffers some limitations in use, since it is obtained in the laboratory through dynamic triaxial tests that require the use of complex, expensive equipment, specialized labor, in addition to demanding a significant amount of material and being difficult to implement in practical situations, making the test restricted outside universities and academic institutions. In view of this problem, this article proposes a neural regression model for predicting the resilience modulus obtained from basic and usual geotechnical parameters. In addition, to prove the viability of the model generated, simulations were carried out considering different types of roads, as well as linear and non-linear elastic soil constitutive models. This demonstrates that it is a satisfactory model for predicting the modulus of resilience that can be used on roads with moderate to heavy traffic volumes, when it is not possible to carry out the test.

Resumo em Inglês:

ABSTRACT The current work presents the thermal analysis of a 12/10 switched reluctance motor (SRM) with modified fin arrangements with different materials for e-vehicle applications. Initially, the parameters for the 12/10 SRM were derived using an analytical expression. Electromagnetic analysis was then performed with MagNet software to obtain motor performance metrics such as torque density, ripple, and losses to ensure that the proposed design meets the requirement. Then, a thermal analysis of 12/10 SRM is carried out using Ansys software. Various fin profiles such as conventional rectangular fins, pin fins, thin fins, tapered fins, and tapered slot fins are employed and analyzed to investigate the effectiveness of heat dissipation in motors. The study shows that the tapered slot fin performs better than the other four fin profiles. This is due to its lower mass of 0.53 kg and efficient thermal management (the maximum temperature of the stator outer cover is 31.6 °C). In addition, different fin materials like aluminium (Al), aluminium with 1% graphene particles (GP), and aluminium with 2% GP were analysed for tapered slot fins, and it was found that aluminium with 2% GP provides a lower fin temperature of around 30.40 °C compared to other fin materials.

Resumo em Inglês:

Abstract The construction industry faces growing pressure to reduce its environmental impact, particularly in resource consumption and waste generation. Textile sludge, a byproduct of textile manufacturing, poses a disposal challenge despite its potential use in building materials. This study explores the feasibility of utilizing textile sludge as a partial replacement for clay in sustainable brick production. Researchers tested the compressive strength of various brick mixtures containing quarry dust, lime, slag, and varying percentages of textile sludge (5%, 10%, and 15%). The results demonstrate that while incorporating textile sludge can affect compressive strength, optimized mixtures can still yield viable bricks, even with up to 15% textile sludge content. This approach promotes resource circularity and advances sustainable practices within the construction industry. These findings are consistent with previous research on utilizing industrial waste in brickmaking. Furthermore, this method could potentially reduce waste and minimize the environmental footprint of cement production by incorporating industrial byproducts like fly ash and lime mud as cementitious components. Additionally, replacing clinker with brick fines in cement manufacturing offers a promising avenue for lowering the building industry's overall carbon footprint.

Resumo em Inglês:

Abstract This study synthesized novel nano-biochar supported TiO2 composites using various methods and biochar/TiO2 ratios to effectively remove dichloroacetic acid (DCA) from swimming pool water. The hydrothermally prepared HBT-5 composite with 5 wt% biochar exhibited the highest photocatalytic activity, degrading 92.5% of DCA within 180 min under UV-vis light irradiation, outperforming pure TiO2 and HBT-1. Comprehensive characterization confirmed the strong interaction and synergistic effects between biochar and TiO2, attributing the enhanced performance to high surface area, pore volume, interfacial Ti-O-C bonding, visible light absorption, efficient charge separation, and N and O heteroatoms in biochar. The photocatalyst showed excellent reusability, maintaining 87.3% of its initial activity after three cycles. This work provides insights into designing biochar-based photocatalysts for water purification, benefiting public health and environmental protection.

Resumo em Inglês:

Abstract This study aimed to enhance the thermal performance of solar thermal collectors using silver nanoparticle-enhanced nanofluids. Silver nanoparticles, known for their high thermal conductivity, were synthesized via chemical reduction, stabilized with polyvinylpyrrolidone, and dispersed in base fluids like deionized water and ethylene glycol. Various nanoparticle sizes (20 nm to 50 nm) and concentrations (0.2 wt% to 0.8 wt%) were tested to optimize thermal conductivity while maintaining stability. Thermal properties were measured using the transient hot-wire method for conductivity, rotational rheometer for viscosity, and differential scanning calorimetry for specific heat capacity. Stability was monitored via UV-Vis spectrophotometry. Results indicated that smaller nanoparticles (20 nm) at lower concentrations (0.2 wt%) yielded the highest thermal conductivity of 0.73 W/mK, due to their high surface area-to-volume ratio. Viscosity increased with nanoparticle size and concentration, peaking at 0.0012 Pa.s for 50 nm nanoparticles at 0.8 wt%. Specific heat capacity remained relatively stable, slightly increasing with larger nanoparticles. Conclusions reveal that optimizing nanoparticle size and concentration is crucial for balancing enhanced thermal conductivity and manageable viscosity. These findings underscore the potential of silver nanoparticle-enhanced nanofluids in improving the efficiency of solar thermal systems, offering valuable insights for future research in sustainable energy technologies.

Resumo em Inglês:

ABSTRACT Geopolymer concrete is produced with use of byproduct are the environmentally friendly and positive impact for workable growth. This research, by products such as fly ash and ground granulated blast furnace slag (GGBS) were utilized as binding material in geopolymer concrete. The main aim of the present study is to replace the coarse aggregate by coconut shell and evaluate the mechanical and durability properties of the concrete by varying the 10%, 20%, 30%, 40% and 50%. The study results indicates that, 40% use of coconut shell shows the high strength behaviour than other variations. In order to evaluate the durability properties, water absorption, rate of absorption, acid resistance and sulphate resistance tests was performed. The study results represented that, fly ash and GGBS shows the strong binding cementitious material while using coconut shell as coarse aggregate. the formation of calcium aluminium silicate hydrate(C-A-S-H) gel and siloxane bonds with coconut shell reduce the acid attack and water absorption capacity of the geopolymer concrete.

Resumo em Inglês:

ABSTRACT This research paper presents a study on predicting the compressive strength of self-compacting concrete (SCC) containing glass aggregate. A stacked ensemble approach was employed, which is a method of combining multiple models to improve the overall performance. The ensemble consisted of gradient boosting, extreme gradient boost, random forest, and K-nearest neighbors regressors as base learners, and linear regression as the meta learner. The SCC components, namely, water-binder ratio (w/b), total binder content, fine aggregates, fine glass aggregates (FGA), coarse aggregates, coarse glass aggregates (CGA), and superplasticizer were taken as input variables and compressive strength as output variables. The hyperparameters of the base learners were optimized using tree based pipeline optimization (TPOT). The ensemble’s accuracy was evaluated using the K-fold cross-validation technique and statistical metrics. The performance of the stacked ensemble models is found to be better than other machine learning models. Permutation feature importance was used to determine the importance of the features in predicting compressive strength. The results demonstrate that the stacked ensemble approach with R2 = 0.9866, RMSE = 1.4730, and MAE = 1.0692 performed better than the individual base learners and the other machine learning models. The water-binder ratio has the highest impact on predicting the compressive strength of SCC containing glass aggregate.

Resumo em Inglês:

ABSTRACT This research used Stir Casting [SC] technique through liquid metallurgy route to exert the ZK60-ZrB2 composites. The dispersoid combination varies in increments of 4 weight percent ZrB2 particles, from 0 to 12 weight percent for the study. We investigated the mechanical characteristics of the produced composites, including their compressive, flexural, impact, tensile strengths and macro hardness, as well as metallurgical properties like micro vickers hardness and micrographs like Optical Microscopy [OM] and Scanning Electron Microscopy [SEM] were done. We also measured a physical characteristic like density for further evaluation. Prepared and evaluated test specimens in accordance with ASTM standards. An increase in ZrB2 reinforcement improves the mechanical, metallurgical, and physical characteristics overall, according to the data obtained. From the inferred results the increase in percentage of density, microhardness, macrohardness, tensile, impact, compression and flexural strength are 35%, 30.37%, 51.02%, 37.5%, 140%,41.66% an 56.97% of values. The OM and SEM examinations confirmed that the ZrB2 particles were spread out evenly in the ZK60 matrix.

Resumo em Inglês:

ABSTRACT This study explores the potential of using foundry sand (FS) as a partial replacement for manufactured sand (M Sand) in conventional concrete, aiming to enhance sustainability in construction practices. The experimental program involved creating concrete mixes using ordinary Portland cement (OPC), coarse aggregate (CA), M Sand, and a constant 1% superplasticizer (SP). The control mix consisted of OPC, CA, M Sand, and 1% SP. Subsequent mixes incorporated FS at replacement levels of 5%, 10%, 15%, 20%, 25%, and 30% of the M Sand by weight. The study assessed the workability, compressive strength, and durability of the concrete mixes. Results showed that FS inclusion up to 25% significantly improved the concrete’s properties, including enhanced compressive strength and durability, suggesting FS as a viable alternative to M Sand. This research not only promotes the use of industrial byproducts but also addresses environmental concerns related to foundry waste management, contributing to the development of eco-friendly construction materials. By utilizing foundry sand, the construction industry can reduce its reliance on natural sand resources, promoting sustainable practices and reducing the environmental footprint.

Resumo em Português:

RESUMO A realcalinização química (RAQ) e a realcalinização eletroquímica (RAE) são procedimentos utilizados como reparo de estruturas em concretos sujeitos à corrosão nas armaduras por ação da carbonatação. A premissa é elevar o pH da solução do poro do concreto, com o intuito de reestruturar o filme passivo das armaduras. A RAE é aplicada em estruturas a 40 anos e apresenta eficácia na reestruturação desta película. Já a RAQ é um método pouco abordado no meio cientifico. Este trabalho sintetiza informações, através de uma Revisão Sistemática da Literatura (RSL) com a técnica de snowballing, foram aderidos 24 trabalhos dos quais levantou-se os principais métodos de aplicação, soluções alcalinas e reações físico-químicas. Foi realizada uma análise comparativa entre a RAE e a RAQ, apesar de serem governados por mecanismos diferentes ambos foram eficazes em um período de tempo de 15 dias para reestabelecer o pH superior a 12, sendo também capazes de reestruturar o filme passivo das armaduras em sistemas com perda de massa decorrentes da corrosão abaixo de 0,25%. As principais lacunas da literatura são referentes aos mecanismos de reação da RAQ, alterações nas propriedades do concreto, duração de ambos os tratamentos e maior pré-disposição a reação álcali-agregado após o tratamento.

Resumo em Inglês:

ABSTRACT Chemical realkalization (CRA) and electrochemical realkalization (ERA) are procedures used to repair concrete structures subject to corrosion in reinforcement due to carbonation. The premise is to raise the pH of the concrete pore solution, with the aim of restructuring the passive film of the reinforcement. RAE has been applied to structures for 40 years and is effective in restructuring the passive film. The CRA is a little discussed method in scientific circles. This paper synthesizes information on these methods, through a Systematic Literature Review (SLR) and snowballing technique, with the adherence of 24 works where the main methods of applying treatments, alkaline solutions and physical-chemical reactions. A comparative analysis was carried out between ERA and CRA, although being governed by different mechanisms both raised the pH of the carbonation front to a value higher than 12, were effective in a period less than 15 days, and were also capable of restructuring the passive film of reinforcement in systems with mass loss due to corrosion below 0.25%. The main gaps are CRA reaction mechanisms, changes in concrete properties, duration of both treatments and greater predisposition to the alkali-aggregate reaction after treatment.

Resumo em Inglês:

ABSTRACT Concrete, the cornerstone of modern building, has certain intrinsic shortcomings, such as poor tensile strength and crack susceptibility. Thus, biomineralization appears to be a promising strategy for repairing concrete construction defects through microbial activity. The most advanced use of this novel approach is Microbiologically-Induced Calcite Precipitation (MICP). Microbial urease enzyme-catalyzed calcium carbonate precipitation is a phenomenon that can be produced in concrete mixes containing zeolite by adding bacteria. This promotes calcite formation, sealing fissures and enhancing longevity. Our study compares M25 Bacterial Concrete (BC) and Conventional Concrete (CC) for optimal mix design and performance. We show by thorough experimentation that adding zeolite and bacteria does not affect the workability of concrete mixtures. In addition, BC has better compressive strength at different curing ages because of the sealing action of calcite precipitation and the synergistic improvement of zeolite. Results show MICP boosts concrete durability and cuts maintenance costs. Our research also looks into the flexural behaviour of beams made of reinforced concrete produced by microbes, offering insights into the structural performance of these novel materials in real-world applications. Materials support SDGs by fostering sustainable production and industrial innovation.

Resumo em Inglês:

ABSTRACT The mechanical properties of magnesium alloy in different molding stages are very important factors to determine its application approaches in engineering. In order to ensure the prediction accuracy of mechanical properties, a TCMSSA-ELM model, which is a hybrid of the sparrow search algorithm (SSA) optimized by the tent chaotic mapping (TCM) algorithm and the extreme learning machine (ELM), is proposed in this study, and the stresses of AZ80 magnesium alloy are predicted by the model through a 812-record dataset. The predicting results indicate that TCMSSA improves the accuracy of ELM model. Compared with ELM model, the data points formed by experimental values of stress and the predicted ones by TCMSSA-ELM model are closer to the ideal 45° line, the average determination coefficient rises by 1.43%, and the average root mean squared error (RMSE) decreases by nearly 61.96%, implying that TCMSSA-ELM model accurately reflects the influence rule of thermodynamic parameters on stress. The novelty of this study is that TCM is used to optimize the population initialization of SSA, which enables SSA to have a higher global search ability, and thus optimizes the weight and threshold selection of ELM, then making TCMSSA-ELM have higher prediction accuracy than other improved ELM models.

Resumo em Inglês:

ABSTRACT This study presents the structural behaviour of cold-formed steel joists with different web-opening shapes. The investigation incorporated both experimental and analytical approaches. The study involved the selection of square and circular web openings, and channel sections were chosen based on site-specific design considerations. In the experimental phase, channel joists were subjected to flexural loading and tested. An analytical investigation was conducted. Finite element (FE) models were developed using the FEM software ANSYS APDL version 16.2. FE models were used to simulate the structural response of the channel joist when subjected to flexural loading. A parametric study was conducted on the basis of simulation and experimental investigation. Factors that influence stiffness and load-carrying capacity considering variables in cold-formed steel channel joists were analyzed. Analytical investigations were conducted. Based on this result analysis, significant effects were observed, indicating a better agreement between the analytical and experimental results. In addition, it was shown that channel joists with circular web openings provide high efficiency in terms of load-carrying capacity and stiffness in web-opening shapes.

Resumo em Inglês:

Abstract The DOE methodology was applied to identify the best combination of variables-Recycled Aggregate (RA), Aluminium Ash dross (AAD), and Magnesium oxide dross (MOD)-to enhance concrete's mechanical properties. Utilising the Response Surface Methodology's Central Composite Design (CCD), the study examined four variables: the concrete's split tensile and compressive strengths at 14 and 28 days. ANOVA was used to test regression models for these factors, with the results displayed in a Pareto chart for visualization. The impact of each independent variable was evaluated, and second-order polynomial equations were devised to represent the models obtained. The findings suggested a positive contribution from the inclusion of RA, AAD, and MOD to improve mechanical properties, though higher levels of their inclusion led to reduced strength. Through surface plots, Pareto charts, and regression analysis, it was revealed that Recycled Aggregate and AAD were the most significant factors distressing compressive strength (CS) and split tensile strength (STS) at both 14 and 28 days. Validation tests were similar to predicted results for both compressive strength and split tensile strength, signifying the consistency of these models in predicting strength properties based on the selected variables.

Resumo em Inglês:

ABSTRACT This study compares concrete mixes incorporating different proportions of recycled aggregates (RA) as replacements for conventional coarse aggregates (0%, 10%, 20%, 30%, 40%, and 50%). It aims to evaluate their mechanical, durability, and environmental properties for practical use. Through a comprehensive experimental program, including tests on fresh and hardened properties, mechanical strength, and durability against water absorption, acid resistance, chloride ion penetration, and sulfate attack, the study assesses the performance of these sustainable mixes. Results show varied influences of RA incorporation on concrete properties, with lower replacement levels maintaining comparable mechanical strength and higher levels exhibiting strength reduction. Environmental assessments indicate significant reductions in embodied carbon and energy consumption with higher RA content. This comparative analysis informs optimal replacement levels for achieving sustainability without compromising performance, advancing understanding of sustainable construction practices, and promoting the adoption of eco-friendly materials in the construction industry.

Resumo em Inglês:

ABSTRACT Magnesium alloys have recently been used in marine applications due to an attractive combination of low density and high strength/weight/ratio. However, the corrosion resistance of magnesium alloys should be improved for practical applications. In this study, BN-TiO2 multilayer films were deposited with different numbers of bilayers (2 and 4) on AZ91 magnesium alloys to enhance the corrosion resistance of magnesium alloys in marine environments. The microstructure and wettability properties of uncoated and multilayer film-coated alloys were comparatively investigated via XRD, SEM, AFM, and contact angle measurement systems. The corrosion performance of uncoated and coated samples has also been evaluated using electrochemical polarization and impedance measurements in artificial seawater. The corrosion performance values of multilayer film-coated alloys were better than the uncoated alloy values. Corrosion resistance and hydrophobicity of coated samples also increased with the number of bilayers owing to the smaller grain size, increased layered interfaces, and high structural density.

Resumo em Inglês:

ABSTRACT The surface damage wear mechanism of GFRP is complex in real time applications due to the anisotropic nature of the material. The main objective of this study is to identify the parameters that affect the wear behavior of GFRP composite made by Hand Layup, VARTMand RTM technique. Most GFRP research has focused on fiber/matrix types, but this current research addresses on critical research gap i.e., fiber volume fraction Vf% and optimizing various wear parameters such as load, sliding distance and sliding velocity in order to understand the wear contribution. The result of L9 orthogonal array under dry sliding wear experiment using pin –on – disc tribometer is analyzed by taguchi and ANOVA to determine the optimal wear rate by considering the smaller the best attribute. The result shows that by increasing fiber volume Vf% up to 7% minimum wear rate is observed in materials produced by VARTM and RTM technique. It is evident that improvement of fiber volume in GFRP increases the wear resistance and produce preferential wear with negligible de-bonding of the reinforcement as per SEM study.

Resumo em Inglês:

ABSTRACT Repeated and multiple traffic loads, along with climatic conditions, influence the mechanical behavior of linear pavements, leading to the formation of cracks that propagate significantly across the wearing surface and result in a loss of load-bearing capacity of the pavement body. To remedy this problem, various reinforcement and repair methods (traditional and modern) are applied to address this issue. The use of geogrids, involving the insertion of sheets at the interfaces of the sub-base layers, has proven effective as an alternative solution due to their mechanical and aesthetic performance. However, these geogrids, primarily serving as a separation layer, are sometimes limited in the gains they make in reducing stresses and strains, since these gains do not exceed 5 to 10%. Consequently, researchers have sought other techniques that provide both separation (to prevent crack propagation) and strengthening (to increase the bearing capacity of the pavement). In this article, we propose to study the reinforcement of rigid cement concrete pavements through an experimental approach, using two laboratory batches, each comprising a number of twenty-two (22) small-scale slabs, with dimensions of 400 × 400 × 50 (mm). The first batch was produced at an ambient temperature of 20°C while the second batch was produced at an elevated temperature of 50°C (arid climate). These slabs will be tested in 4-point bending, after reinforcement with different combinations of geogrids and carbon fibers composites. To compare the experimental results obtained, a numerical simulation based on the finite element method, using appropriate software, was conducted. The results regarding stresses and strains, as well as dissipation energy, showed that the combination adopted is very effective, yielding gains of up to 20 to 35%, additionally the integration of geogrids, with the addition of the composite, enhances the reinforced pavement’s longevity, ensuring long-term savings on its upkeep and maintenance.

Resumo em Inglês:

ABSTRACT Natural fiber reinforced composite materials are used to make the best outcome materials due to their ease of availability, ability to be recycled, and environmental friendliness. The items made from this substance can help both urban and rural locations. Borassus flabellifer L fruits, leaves, and stems are commercially used, although some are discarded as scrap. This byproduct of Borassus-Flabellifer L can be utilized as a fiber source and as the principal component of natural fiber polymer composites with reinforcement. Apart from conventional methods of water retting or dew retting and mechanical decortication to extract the fiber, in this study new novel methods of extraction take place. An examination is conducted on Borassus Flabellifer fruit fibers that have been treated with alkaline and peroxide solvents. The purpose of this inquiry is to assess the possibility of using these fibers as reinforcement in composites. The presence of cellulose, hemicellulose, and lignin can be determined by conducting a chemical analysis. The effect of various chemical treatments on morphological attributes is assessed using SEM and UTM techniques. The X-ray diffraction examination reveals that the crystallinity of the fibers is altered by various chemical treatments, as observed in both the untreated fibers and those subjected to chemical treatment (i.e.,) Alkali (NaOH), Hydrogen peroxide (H2O2) and NaOH + H2O2. The effectiveness of Borassus Flabellifer fruit fibers as a component of natural polymer composites is examined.

Resumo em Português:

RESUMO O solo-cimento depende do melhoramento das suas características para garantir adequado desempenho como sistema construtivo. Diante disto, este estudo partiu do solo-cimento autoadensável com aditivo superplastificante e microfibras de polipropileno (SCAAF) para analisar a influência destas adições no comportamento frágil do compósito. Para tal, foram selecionadas misturas de SCAAF com potencial uso em paredes e aplicado os ensaios de compressão axial, de flexão por 4 pontos e de variação dimensional. Os resultados mostraram que a adição da microfibra no SCAAF aumentou a incorporação de ar, diminuiu a massa específica aparente seca e foi ineficaz no controle da retração linear durante a secagem. Por consequência, afetou negativamente à resistência à compressão simples e à flexão; e a ductilidade foi prejudicada pela baixa capacidade de ancoragem da matriz cimentícia as fibras. No entanto, foi relevante o uso da microfibra para o estado pós-fissuração do SCAAF, pois aumentou a tenacidade e reduziu a fragilidade do compósito. O SCAAF caracterizou-se como material isotrópico, com capacidade de lançamento e conformação adequados para aplicação em paredes monolíticas sem a necessidade de adensamento, alcançando aos 28 dias de idade valores de resistência à compressão simples e à flexão, respectivamente, na ordem de 4,5 MPa e 1,4 MPa.

Resumo em Inglês:

ABSTRACT Soil-cement depends on improving its characteristics to suitable performance as a built environment. In view of this, this study started with self-compacting soil-cement with a superplasticizer additive and polypropylene microfibers (SCSCF) to analyze the influence of these additions on the composite's brittle behavior. To this end, SCSCF mixtures with potential for use in wall construction were selected and the axial strength, 4-point flexion and dimensional variation by drying tests were applied. The results showed that the addition of microfiber to the SCSCF increased the incorporation of air into the system, decreased the apparent dry mass and was ineffective in controlling linear shrinkage during drying. Consequently, it negatively affected the strength to axial and flexion; and ductility was harmed by the low anchoring capacity of the cement matrix to the fibers. However, the use of microfiber for the post-cracking state of the SCSCF was relevant, as it increased the toughness and reduced the fragility of the composite. The SCSCF was characterized as an isotropic material, with launch and conformation capacity suitable for use in monolithic walls without the need for densification, reaching at 28 days of age axial and flexion strength values, respectively, in the order of 4.5 MPa and 1.4 MPa.

Resumo em Inglês:

ABSTRACT The study evaluates two methods for producing glass-fiber reinforced polyester (GFRP): the traditional spray-up process and a modified method named Resin Spraying with Vacuum Assisted Molding (RSVAM). Manufacturing processes for resin composites are briefly reviewed, with detailed description of RSVAM. Tensile, flexural, and Izod impact strength tests were conducted on GFRP samples containing 30 wt.% fiberglass from both methods. RSVAM yielded 120 samples (40 per test type), with results including average tensile strength (31 ± 3 MPa) and modulus (6.2 ± 0.2 GPa), flexural strength (157 ± 7 MPa) and modulus (7.2 ± 0.1 GPa), and Izod impact resistance (107 ± 2 J/cm). Comparison with 120 samples from the spray-up method revealed no significant difference in tensile and flexural strengths at a 5% significance level, but RSVAM samples showed 168% higher Izod impact resistance. Reliability curves, based on parametric and nonparametric statistics, predicted failure probabilities. For tensile and flexural tests, normal and Weibull distributions were analyzed, with similar outcomes favoring Weibull for flexural tests. Nonparametric analysis was suitable for Izod impact results, showing significant differences in failure probabilities between the two processes.

Resumo em Inglês:

ABSTRACT This study investigates the use of WFS as a sustainable substitute for fine aggregate in concrete, aiming to enhance environmental sustainability and reduce waste material impact.The research explores the mechanical and microstructural properties of concrete incorporating WFS through various experimental techniques, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) spectroscopy. Concrete mixes were prepared with incremental WFS substitutions ranging from 10% to 100%. Key findings reveal that a 45% replacement level of WFS is optimal, significantly enhancing concrete performance. Specifically, this substitution increased compressive strength by 58%, split tensile strength by 48%, and flexural strength by 43% compared to the control mix. SEM analysis showed improved particle cohesion and bonding at this level, contributing to greater strength and durability. These results underscore the potential of WFS as a viable replacement for natural sand in concrete production, offering significant environmental and economic benefits. The adoption of WFS can reduce the reliance on natural resources and improve waste management practices, thereby promoting a circular economy and minimizing the environmental footprint of construction materials. This research contributes valuable insights into the material properties of WFS and demonstrates its practical and sustainable application in concrete production.

Resumo em Português:

RESUMO No Brasil, é comum a aplicação de coagulantes químicos durante as etapas de tratamento da água potável, o mais utilizado entre eles é o sulfato de alumínio (Al2(SO4)3), considerado prejudicial à saúde, podendo causar doenças neurológicas. Durante o período chuvoso, os níveis de partículas suspensas na água aumentam fazendo com que seja necessário adicionar uma maior dosagem de coagulante convencional gerando assim, um alto custo comercial para as adutoras, podendo até não chegar de forma devidamente tratada ao consumidor. Considerando alguns aspectos negativos da aplicação desse tipo de coagulante, o presente trabalho investiga a semente de Moringa oleífera como potencial coagulante natural a ser utilizado durante o processo de tratamento de água. Foram realizados ensaios de corrosão por imersão (30, 60 e 90 dias) e posteriormente, ensaios eletroquímicos Open Circuit Potential (OCP) e Polarização Linear (PL) aplicadas em amostras de aço patinável CST COR 400 (revestidas com tinta epóxi, sem revestimento (neutra) e com a presença de cordão de solda) oriundas de tubulação de uma adutora. Realizou-se também análises de microscopia óptica (MO) e caracterização do pó através da leitura de infravermelho por transformada de Fourier (FTIR). Os estudos concluíram que para a biocoagulação e clarificação da água bruta do rio a dosagem de 200 mg/ 200 ml é a mais adequada, pois não alterou pH e turbidez estando nos padrões de potabilidade. Já nos ensaios de corrosão por imersão, o aço com a proteção de tinta epóxi teve um equilíbrio quanto a perda de massa, o contrário aconteceu com a amostra neutra. O FTIR identificou a suave presença de elementos como o brometo que auxilia no processo oxidativo e em maior quantidade a presença de aldeído e aminas que auxiliam no processo como inibidores de corrosão.

Resumo em Inglês:

ABSTRACT In Brazil, it is common to apply chemical coagulants during the drinking water treatment stages, the most used among them is aluminum sulfate (Al2(SO4)3), considered harmful to health and may cause neurological diseases. During the rainy season, the levels of suspended particles in the water increase, making it necessary to add a higher dosage of conventional coagulant, thus generating a high commercial cost for the pipelines, which may even not reach the consumer in a properly treated form. Considering some negative aspects of the application of this type of coagulant, the present work investigates the Moringa oleifera seed as a potential natural coagulant to be used during the water treatment process. Immersion corrosion tests were carried out (30, 60 and 90 days) and subsequently, Open Circuit Potential (OCP) and Linear Polarization (PL) electrochemical tests applied to CST COR 400 weathering steel samples (coated with epoxy paint, without coating (neutral) and with the presence of a weld bead) originating from a water main piping. Optical microscopy (OM) analyzes and powder characterization were also carried out using Fourier transform infrared (FTIR) reading. The studies concluded that for biocoagulation and clarification of raw river water, the dosage of 200 mg/ 200 ml is the most appropriate, as it did not change pH and turbidity, being within potability standards. In the immersion corrosion tests, the steel with epoxy paint protection had a balance in terms of mass loss, the opposite happened with the neutral sample. The FTIR identified the slight presence of elements such as bromide that helps in the oxidative process and in greater quantities the presence of aldehyde and amines that help in the process as corrosion inhibitors.

Resumo em Inglês:

Abstract This paper explores the use of novel lightweight concrete as an alternative material, focusing on Cellular Lightweight Foam Concrete (CLFC), renowned for its strength, low weight, thermal insulation, and sustainability. The study encompasses a thorough review of literature focusing on the evolution of lightweight concrete, experimental investigation including mix design variations and mechanical property analysis, statistical analysis using MINITAB software, SEM and EDS interpretation, and construction of model POD. Regression analysis was performed to investigate on the factors influencing compressive strength, revealing significant predictors such as cement, fly ash, water, and density, paving the way for enhanced concrete mixes. Characterization studies such as SEM and EDS were performed to analyse the formation of elements that contribute to the strength parameter. Moreover, the study underscores the potential of utilizing steam curing cycle to achieve early compressive strength in concrete mixes. Ultimately, the research aims to revolutionize construction practices by advocating for the widespread adoption of CLFC and innovative construction techniques to meet the demands of low-cost, eco-friendly housing.

Resumo em Inglês:

ABSTRACT Regular concrete uses a lot of cement, which is bad for the environment. Adding plastic waste to concrete as a substitute reduces pollution, but it can weaken the concrete. This study tackles this problem by creating an eco-friendly concrete alternative. The researchers mixed shredded PET plastic bottles (up to 10%) with concrete and replaced some cement (up to 10%) with nano-silica. They tested how this affected the concrete’s strength in different ways (bending, splitting, and compression). Interestingly, they found that using a specific mix (4% plastic and 4% nano-silica) actually made the concrete stronger! This suggests a promising new way to use recycled plastic to create a more sustainable and even stronger building material.

Resumo em Inglês:

ABSTRACT In order to enhance the quality and mechanical properties of 3D printing carbon fiber reinforced composite (CFRP) workpiece, this paper prepares 3D printing CFRP laminates by proposing a layered coherent composite scanning path, and carries out orthogonal tests and single factor tests to disclose the effects of different process parameters (i.e., layer thickness, first layer thickness, nozzle temperature and printing speed) on the mechanical performance of the CFRP workpieces. Moreover, The grey relation analysis method is used to analyze the multi-objective parameters of the orthogonal tests results and the process parameters of 3D printing CFRP are optimized based on the tests results. The research results show that the process parameters of 3D printed CFRP can be ranked as delamination thickness, nozzle temperature, first layer thickness and printing speed, in descending order of the impact on the mechanical property of the CFRP laminates. the optimal process parameters for 3D printing include a layer thickness of 0.25 mm, a first layer thickness e of 0.2 mm, a nozzle temperature of 180°C, and printing speed of 45 mm/s. Under this parameter combination, the tensile strength, bending strength, and the interlaminar shear strength (ILSS) of the samples are 52.77 MPa, 276.63 MPa and 38.56 Mpa respectively, and the grey correlation degree increased to 0.845.

Resumo em Inglês:

ABSTRACT Carbon fiber reinforced aluminum laminates (CARALL) are often subjected to bending loads in actual working conditions, resulting in some imperceptible intra-layer or inter-layer damages, such as matrix cracking, fiber fracture and inter-layer delamination, which degrade the mechanical properties of the structure. In this paper, the bending performance and damage mechanism of CARALL are tested and simulated by finite element simulation. Firstly, the mechanical properties are analyzed by three-point bending test, and the fracture morphology of the specimen after failure is photographed by scanning electron microscope, and the failure damage state from the microscopic perspective is analyzed. Secondly, the VUMAT subroutine with built-in three-dimensional Hashin criterion is introduced into ababqus. By comparing the finite element simulation and experimental results, the rationality and accuracy of using VUMAT subroutine to predict the failure behavior of Al-CFRP-Al laminates are verified. The results show that during the bending failure process, the aluminum alloy layer suffered local damage, and the carbon fiber layer suffered a large area of damage. The layer near the indenter was subjected to large stress concentration during bending, resulting in intensified interlayer interaction and serious damage. The crack began to expand downward along the stress and gradually became smaller as it expanded. The research results provide basic data reference for the bending performance and damage mechanism of fiber metal laminates (FMLs), and have important engineering application value for the optimization design of related structures.

Resumo em Inglês:

Abstract The morphological characteristics of metallic surfaces play a crucial role in the adhesion, retention, and growth of bacteria and fungi. Laser-induced periodic surface structures (LIPSS) present potential to controlling biofilm formation on biocompatible metallic surfaces for biomedical and engineering applications. LIPSS have emerged as a promising technique for controlling biofilm formation on biocompatible metallic surfaces in various biomedical and engineering applications. This present work uniquely focuses on investigating the effects of LIPSS on AISI 316L stainless steel (AISI 316L SS) as a potential inhibitor against the adhesion of bacteria and fungi (E. coli and C. albicans, respectively) on laser-textured surfaces. Microstructural characterization through scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), roughness profiling, and X-ray diffraction (XRD) revealed morphologic alterations of the laser-treated surfaces, resulting in the formation of LIPSS with laser fluences of 2.1 J/cm2 and 2.8 J/cm2, line spacing approximately equivalent to the laser wavelength (532 nm), and average roughness values of 96 nm and 209 nm, respectively. The study found that LIPSS exhibited inhibitory effects against E. coli biofilm formation on laser-textured surfaces, with a noticeable enhancement in antimicrobial efficiency ranging from 30% to 43% compared to untreated surfaces. However, the antimicrobial effectiveness against C. albicans was notably lower, with marginal improvements observed under specific conditions. Thus, the results showed a complex interplay between surface morphology, microbial adhesion, and antimicrobial efficacy on laser-textured metallic surfaces. These findings underscore the dependence of the antimicrobial properties of laser-textured surfaces on the type of microorganism and laser processing parameters.

Resumo em Inglês:

ABSTRACT Mycelium-bound composite substances are a novel class of sustainable and economical bio composites that were recently developed as an alternative to typical synthetic materials in packaging, fashion, and architecture. Extensive research has been carried out in recent years to study the methods of manufacture and processing, as well as prospective uses for mycelium-bound composite materials. However, the usage of this bio-composite in the construction industry is confined to small-scale prototypes and display exhibits. The main challenges that need to be address when employed as non-structural or semi-structural components are the water absorption, mechanical characteristics and the standard techniques for manufacture and testing of mycelium-bound composite materials as building insulation or blocks. Hence this paper describes the usage of novel Pleurotus ostreatus-mycelium fungal blocks to enhance the indoor thermal preformance of the building. To develop distinct mixing protocols with various substrate materials such as straws, coir pith, saw wood and the combination of the all the substrate were used in the present work. The parameters such as density, thermal resistivity, compressive strength and fire resistant were determined and it was found that the composition of the substrate is highly variable in the tested considered in the work. Straw and coir pith substrate showed a high strength and the thermal resistivity in comparison with the other substrates. Also, the findings show that the mycelium fungal based blocks have a lot of potential for use as an alternative material for insulation for building and infrastructure development, especially as a light-weight material for engineering applications.

Resumo em Inglês:

ABSTRACT Day by day, the percentage of waste increased at an enormous rate due to the increase in population. Utilization of industrial waste in concrete not only prevents the duplication of natural resources but also helps to minimize waste disposal issues. One of the industrial byproducts used in geopolymer concrete is fly ash, which serves as the main source material and is highly rich in alumina and silica. In this study, Quarry rock dust is used as fine aggregate which replaces natural river sand. Recycled coarse aggregate and metal swarf was added in 50:50 proportion with respect to the volume of concrete to replace coarse aggregate. Alkaline activator solution, also called stimulator solution a combination of sodium hydroxide and sodium silicate, is added into the concrete. Polyethylene-based superplasticizer with 1% of the volume of fly ash is mixed into the concrete to increase its workability. Coir fibers (lignocellulosic fibers) are added to the concrete in percentages range from 0.2% to 1.2% at 0.2% interval. The specimens are tested for their compressive strength, water absorption, acid attack, and sulfate attack. Fibres below 0.6% dosage produced the optimum results.

Resumo em Inglês:

ABSTRACT The fabrication technology of SLM forming Al-Mg-Sc-Zr alloy is widely used in the lightweight structure design of spacecraft. However, there is a need to optimize the process parameters and heat treatment process. The study analyses the process parameters of SLM on the forming density, microstructure and mechanical properties. The results show that the influence of laser power on the relative density is the greatest, followed by the scanning distance, and the scanning speed is the least. The optimal process parameters of Al-Mg-Sc-Zr are obtained as follows: the laser energy density is 130–140 J/mm3, laser power is 360 W, scanning speed is 1100 mm/s, and scanning spacing is 80 μm. Finally, samples with an average pore size of 15 μm and a relative induced density of 99.9% were obtained. On this basis, the effects of different annealing systems on the microstructure and mechanical properties were studied. Due to a large amount of second-phase precipitation in the remelting zone, the edge of the molten pool and the bottom, it has a pinning effect, which effectively inhibits recrystallization and grain growth during liquid phase solidification, and no abnormal grain growth occurs during the annealing process. The results show that after low-temperature annealing with 325°C insulation for 4 h, the mechanical properties were significantly enhanced and the maximum ultimate tensile strength (UTS) of the sample could reach 524.89 MPa, the maximum yield strength (YS) of the annealed sample can reach 506.01 MPa, the elongation rate of the annealed sample can reach 5.24%, the dimples and defects at the fracture interface were significantly reduced after annealing.

Resumo em Inglês:

ABSTRACT Nowadays, Recyclability of huge quantity of waste materials generated in industries to form new materials. The current research is also focuses on utilization of waste materials produced by industry to form new hybrid brick for sustainable the environmental condition, technical aspects, and low production cost in construction field. In this paper hybrid brick specimens are manufactured using waste materials of clay, ceramic waste powder and sugarcane bagasse ash with various mix proportions. These bricks are tested in compression test, soundness test and water absorption test as per Indian Standards. It was observed that clay bricks incorporating ceramic waste powder (10%) and sugarcane bagasse ash (10%) exhibited high compressive strength, less water absorption, less efflorescence, good metallic ringing sound compared to other hybrid bricks leading to protect the environmental stability and keep away from hassle of ash disposal. The combination of ceramic powder and sugarcane bagasse ash residue increases the compressive strength of the clay samples (B2) to 27.2 MPa, and the composition of Brick B2 exhibits decreased water absorption percentage up to 11.4%.

Resumo em Inglês:

ABSTRACT The paper deals with the results of an experimental investigation related to the properties of fly ash-lime-gypsum-quarry dust (FALGQ) bricks and their masonry. The strength, absorbing capacity, and efflorescence of FALGQ were examined. In addition, concrete՚s strength, the cement mortar and fly ash brickwork՚s stress-strain properties, and the flexure՚s resistance to cracking were also studied. The results show that: (1) FALGQ can be produced with a greater density using a fly ash-sand combination than with fly ash alone; (2) it is feasible to achieve 12 to 14 MPa strength development in a wet condition, a relatively low value of absorption of water, strong dimensional stability and strength properties for FALGQ using 35% lime, 10% quarry dust, and 30% gypsum; and (3) high rupture elasticity and deformation significantly impact in fly ash brick masonry. This study also contrasts the durability of bricks with that of burned clay bricks, specifically examining weight reduction and the decrease in strength qualities resulting from an acid test.

Resumo em Inglês:

ABSTRACT In order to meet sustainability criteria and reduce carbon emissions associated with the production of cement and its related composites, it is necessary to completely replace Ordinary Portland Cement (OPC) with a new binding substance. This study focuses on a novel method of manufacturing geopolymer concrete by utilizing a single activator instead of the traditional two activators. An analysis was conducted on the mechanical properties and microstructure of geopolymer concrete made from several source materials, including Fly ash (FA), granulated blast furnace slag (GGBS), and nano silica (NS). The findings indicated that the mechanical characteristics of GPC, generated by combining 80% GGBS and 20% FA, using a single source alkali activation method under ambient curing conditions for 28 days, had superior performance compared to other mixtures. Additionally, there was a decrease in carbon emissions.

Resumo em Inglês:

ABSTRACT Effectively managing waste from pultruded composite materials is a pressing concern within the composites industry, given their composition of thermosetting resins. Currently, much of this waste ends up in landfills or is incinerated, despite the considerable environmental repercussions. Thus, repurposing pultruded waste for construction purposes not only enhances environmental sustainability but also provides a dependable source of construction materials. In M30 grade concrete structures, composite structures such as pavement slabs can be engineered with superior split tensile strength compared to existing alternatives, while still meeting required compressive strength specifications outlined in the mix design, by substituting fine waste (FW) for fine aggregate (filler) at a rate of ≥ 2.5wt%.

Resumo em Português:

RESUMO A compreensão dos fenômenos envolvidos na corrosão do aço carbono em meio H2SO4 é de fundamental importância, visto que este é o principal produto da indústria química. Contudo, poucos trabalhos recentes relacionados a corrosão do aço carbono em H2SO4 em diferentes concentrações de sulfato são reportados. O presente trabalho objetivou estudar a corrosão do aço carbono em H2SO4 1 mol L–1 sob incremento de íons SO42– de origem salina. Medidas de potencial a circuito aberto, ensaios de imersão com perda de massa, quantificação do teor de íons ferro total em solução e curvas de polarização potenciodinâmica foram realizadas e sugerem que a corrosão do aço carbono em H2SO4 com adição de sulfato ocorre por mecanismo de dissolução-passivação, sendo influenciada pela concentração de sulfato adicionado. Micrografias da superfície do aço carbono denotam que a corrosão ocorre de maneira uniforme e com a formação de produtos de corrosão insolúveis distribuídos não homogeneamente na superfície metálica. Tais produtos estão provavelmente associados à precipitação de FeSO4 e/ou Fe(OH)3 na superfície.

Resumo em Inglês:

ABSTRACT Understanding the phenomena involved in the corrosion of mild steel in H2SO4 media is of fundamental importance as it is a principal product of the chemical industry. However, a few recent studies have reported the corrosion of mild steel in H2SO4 at different sulfate concentrations. This study aims to investigate the corrosion of mild steel in 1 mol L–1 H2SO4 with the addition of sulfate ions from saline sources. Open-circuit potential measurements, immersion tests with mass loss, quantification of total iron ion content in solution, and potentiodynamic polarization curves were conducted. This suggests that the corrosion of mild steel in H2SO4 with added sulfate occurs via a dissolution-passivation mechanism, which is influenced by the concentration of added sulfate. Micrographs of the mild steel surface indicate that corrosion occurs uniformly with the formation of insoluble corrosion products that are non-homogeneously distributed on the metal surface. These products were likely associated with the precipitation of FeSO4 and/or Fe(OH)3 on the surface.

Resumo em Inglês:

ABSTRACT In conjunction with experimental studies, computational tools based on the Finite Element Method (FEA) have made it possible to analyze the phenomenon of punching and the influence of prestressing on the ultimate strength of flat slabs and thus understand this phenomenon through numerical simulations. In this study, experimental tests were simulated through three-dimensional analyses, using the constitutive models implemented in the ATENA 3D computer program, it was possible to validate the numerical results through the load-displacement and load-strain curves being compared with the experimental curves. The numerical results showed a difference in load capacity of less than 2% for the experimental models. After adequate calibration, a parametric study with eight models of prestressed slabs was implemented by varying the spacing and eccentricity of the prestressing tendons, punching resistance being evaluated with the new parameters. The punching resistant capacity of each model was also compared with the most current regulatory design predictions.

Resumo em Inglês:

ABSTRACT The wet beneficiation process of ornamental stone generates waste in the form of sludge that, after drying, becomes a non-biodegradable fine powder. Its improper disposal can lead to various negative environmental impacts. Therefore, new destinations for waste should be evaluated in search of innovation and sustainability. In Brazil, this issue is of particular interest since the country stands out globally as one of the largest producers of ornamental stone, generating significant quantities of waste annually. Thus, mortars with replacement percentages (5, 10, 15, and 20 wt.%) of Portland cement (PC) by ornamental stone waste (OSW) were analyzed as supplementary cementitious material (SCM). The analysis included compressive strength tests, ultrasonic pulse velocity (UPV) at 7- and 28-day curing, X-ray diffraction, and a simplified carbon dioxide (CO2) emissions analysis. The results indicated that the partial replacement of PC by OSW up to 20% resulted in compressive strengths at 28 days statistically equal to the control sample, which can be attributed to the formation of AFm phases. When analyzing the CO2 emissions of the samples, higher substitution percentages were associated with lower reported emissions, reaching a reduction of 61.4% when comparing the 20% replacement with the reference.

Resumo em Inglês:

ABSTRACT This study investigates the thermal and mechanical properties of fiber-wrapped concrete specimens compared to a nominal mix without fibers, subjected to elevated temperatures of 250°C and 500°C over varying durations. Compressive and split tensile strengths were evaluated to assess the effectiveness of basalt, aramid, and hybrid (basalt + aramid) fiber configurations in enhancing concrete's resilience under thermal stress. Results indicate that fiber-wrapped samples consistently outperform the nominal mix in both compressive and split tensile strengths across all testing conditions. At 250°C, after 1 hour, compressive strengths ranged from 19.77 N/mm2 (nominal mix) to 21.08 N/mm2 (basalt + aramid strips), showcasing the protective role of fibers. Similarly, split tensile strengths at the same conditions varied from 2.03 N/mm2 (nominal mix) to 3.11 N/mm2 (basalt + aramid strips), highlighting significant improvements with fiber reinforcement. At 500°C, the nominal mix exhibited substantial strength degradation over time, whereas fiber-wrapped samples maintained higher strengths, particularly in hybrid configurations. These findings underscore the beneficial impact of fiber reinforcement in mitigating thermal-induced strength loss in concrete, suggesting practical applications in industries requiring fire-resistant structural materials.

Resumo em Inglês:

ABSTRACT To ensure the viability of bacteria in the biomineralization process for crack filling and healing, protection from the heat (generated by cement hydration) and the retraction (during hardening) of the microorganisms is required. Superabsorbent polymers, as chitosan, known for their resistance during mixing and water storage capacity, are suitable bacteria carriers. This study aimed to determine the optimal percentage of chitosan capsules and its effects on the physical and mechanical properties in mortars. Mortar formulations containing 0.5%, 1.0%, and 1.5% of chitosan capsules (relative to the total cement weight) were developed keeping the original granulometric distribution. Analysis of variance (ANOVA) for each individual property and post-hoc tests with corrections of Bonferroni and Tukey demonstrated that the formulation significantly impacted both properties through aging. Formulations AQ-0.5C and AQ-1.0C (0.5% and 1.0% of capsules respectively) maintained the flow levels comparable to the original formula. AQ-0.5C showcased the most favorable outcomes, exhibiting mechanical resistance up to 10% higher than the capsule-free original formula. Even slightly inferior results, AQ-1.0C still presented a higher strength mechanical up to 5% over the original formula. These results indicate the potential use of the ionotropic gelation to produce spores with bacteria to be applied in biomineralization for sealing cracks.

Resumo em Português:

RESUMEN En este trabajo de investigación se estudió sistemáticamente el efecto del pH sobre la formación de la fase hexagonal del óxido de tungsteno usando el método hidrotermal. Se varío el pH de la solución precursora en 1, 2 y 3 y se usó un reactor autoclave hidrotermal de 50 y 200 ml. Se realizaron tratamientos térmicos post síntesis a 350 °C y 400 °C durante un tiempo de 2 horas. Los resultados de FE-SEM nos muestran el efecto del pH en la morfología, observándose la formación de nanobarras para un pH 1, nanovarillas a un pH 2 y nanotubos a un pH 3. De igual manera, de los resultados de NTA se observa un crecimiento del tamaño de partícula, a cualquier pH, al incrementar la temperatura de tratamiento térmico. De igual manera, al incrementar el volumen del reactor autoclave hidrotermal se observa un incremento en el diámetro de los nanotubos. Del análisis de los resultados de DRX, se observa la formación de la fase hexagonal como una fase predominante en todas las muestras. A pH 1 y 2 se observa también la fase monoclínica y ortorrómbica, respectivamente, y a pH 3 solo la fase hexagonal es presente.

Resumo em Inglês:

ABSTRACT In this research work, the effect of pH on the formation of the hexagonal phase of tungsten oxide was systematically studied using the hydrothermal method. The pH of the precursor solution was varied at 1, 2 and 3 and a 50 and 200 ml hydrothermal autoclave reactor was used. Post synthesis heat treatments were performed at 350 °C and 400 °C for a time of 2 hours. The FE-SEM results show the effect of pH on the morphology, observing the formation of nanowhiskers at pH 1, nanorods at pH 2 and nanotubes at pH 3. Similarly, from the NTA results, particle size growth is observed with increasing heat treatment temperature, regardless of the pH value. Similarly, by increasing the volume of the hydrothermal autoclave reactor, an increase in the diameter of the nanotubes is observed. From the analysis of the XRD results, the formation of the hexagonal phase is observed as a predominant phase in all samples. At pH 1 and 2 the monoclinic and orthorhombic phase is also observed, respectively, and at pH 3 only the hexagonal phase is present.

Resumo em Inglês:

Abstract Growing industrialization leads to a large amount of trash being disposed of, which puts the environment at risk. A significant issue for these sectors is the disposal of the Industrial By-Products/Waste produced by the industry, which results in ground water contamination and an average annual production of 3 million tons of caustic waste. In both developed and developing nations, the rate of urbanization and industrialization rises with the production of industrial waste. The recycling or use of industrial waste by-products has grown in popularity as a disposal option due to growing environmental awareness of potential harmful impacts. This study finds a chance to assess the results of using substitutes for both fine and coarse materials with copper slag, iron slag and recycled concrete aggregate with varying amounts of mix. The mechanical parameters of both the recommended mix and normal concrete were measured and compared during the 28-day curing period. Results were intended to show the proper mix proportion that would produce the highest mechanical strength. The above-mentioned proportions were the subject of an experimental investigation. The study found that adding recycled concrete aggregate to conventional concrete mix strengthened it by 40% RCA, 40% iron, and 25% iron slag.

Resumo em Inglês:

ABSTRACT The construction industry is continually seeking new waste materials and techniques to enhance the sustainability and overall performance of concrete. High Strength Self-Compacting Concrete (HSSCC) is a type of concrete suitable for modern construction that offers superior mechanical properties and excellent workability. In this investigation, the compressive strength of HSSCC containing varying proportions of marble dust is predicted using an Artificial Neural Network (ANN). An exhaustive dataset collected from laboratory tests encompasses a variety of mix designs with different proportions of marble dust. The integration of marble dust, a by-product of the marble industry, into HSSCC gives a sustainable approach for overall performance of concrete. The parameters considered in the studies include the water-cement ratio, marble dust content, and quartz sand content. The results indicate that the ANN model can accurately predict the compressive strength of HSSCC. The key finding indicate architecture 3-4-1 was found to be the most effective in achieving a high regression value of 0.937.

Resumo em Inglês:

ABSTRACT Newly developed high-performance concrete (HPC) is a revolutionary building material with superior mechanical properties and enhanced durability. Researchers have optimized HPC by incorporating industrial byproducts like modified ferro slag, silica fume, and fly ash, promoting sustainability and reducing carbon emissions. This paper analyzes the mechanical characteristics of HPC using the American Concrete Institute (ACI-211.1-91) guidelines, substituting cement with 17% fly ash (FA) and 10% silica fume (SF), and replacing coarse aggregate with up to 40% modified ferro slag. M60 grade was adopted for all mixes. Experimental tests assessed compressive strength (CS), split tensile strength (STS), and flexural strength (FS). Results showed significant improvements, with CS surpassing conventional HPC mixes by up to 25%. The highest CS, STS, and FS were observed with 30% modified ferro slag, achieving 10%, 6%, and 9% increases, respectively, at 28 days. These improvements indicate enhanced structural integrity and resistance to cracking. Utilizing industrial byproducts in HPC not only boosts performance but also supports sustainable construction by reducing waste and conserving natural resources.

Resumo em Inglês:

Abstract Metal forming is a crucial technique for shaping sheet material to specific dimensions. Predicting strain in formed components is essential for evaluating sheet metal formability. This study investigates the measurement of major and minor strain on curved surfaces formed through a single-point incremental forming process using photogrammetry and validates the results. The aim is to measure strain on a curved surface post-forming by applying circle grids on the sheet metal before forming. A system was developed to capture deformed circle grids and compare the deformation with the original diameter to calculate strain. A Forming Limit Diagram was plotted to analyze the formability of the sheet metal. Statistical methods were used to predict the confidence interval level of the developed strain. The average percentage error of the strain obtained through 3D photogrammetry method compared to the experimental results is approximately 1.91% and 2.93% for the major and minor axes, respectively. These findings demonstrate that photogrammetry analysis of strain on curved surfaces is more accurate than traditional experimental methods.

Resumo em Inglês:

ABSTRACT Cassava used in various processing industries needs new tools and technology to ensure it's the final quality Cassava product based on the component exists in the raw root to make the final product competitive. Modifying industry currently uses the traditional wet chemical method for ingredient identification as per Indian Standard assessment system developed in 1978. It was expensive, take prolonged testing time, need skilful worker involvement and chance of toxic byproduct formation. This paper focuses on the pre-determined raw material quality feeding for suitable starch industry through raw Cassava categorization based on its active constituent presence to meet the final quality of modified Cassava starch by integrating Fourier Transform Infra-Red spectroscopy (FTIR) with Partial Least Square (PLS) algorithm. The classification of raw cassava logs based on its ingredient concentration (ash and moisture) implemented through Support Vector Machine algorithm according to the industrial standard requirements needed by the third party users for guaranteed final quality product from raw materials observation.

Resumo em Inglês:

ABSTRACT Researchers are working towards achieving the good strength, finding sustainable material, high performance; improve the structural & durability behaviour etc., of the concrete. This study focuses on the analysis and benefits of addition of raw (RFAC), ultra fine (UFFAC) and nano fly ash (NFAC) on its optimum level in the concrete. The optimum content of raw, ultra fine and nano fly ash is 19%, 22% & 23% are obtained through mechanical properties tests. To find the flexural performance of reinforced concrete beam, the specimen of 2000 mm*100 mm*150 mm has been designed to with stand the load of 35kN. Under the static load, the parameters of load vs. mid span deflection, moment vs. rotation, ductility, energy absorption are calculated and all the results were compared with conventional (CC) specimen. Among all the specimens, NFAC specimens have performed well and the minor cracks are developed due to its high bond between the ingredients. The load carrying capacity of the NFAC specimen has been improved about 9.23%, 8.64% and 5.20%, the deflection has been reduced by 12.32%, 9.70% and 1.63%, also the moment carrying capacity of the NFAC specimen has been improved by 19.66%, 12.90% and 5.26% with respect to CC, RFAC and UFFAC specimens.

Resumo em Português:

RESUMO Esta pesquisa avaliou as vantagens e desvantagens da substituição da areia por resíduo cerâmico no Concreto Autoadensável para produção de blocos intertravados. O subproduto foi obtido em armazém de uma loja comercial dedicada à construção civil na cidade de Maceió-Brasil e processado em moinhos de bolas em laboratório. O material foi caracterizado por Fluorescência de Raios X e Difração de Raios X e seu tamanho de partícula foi avaliado. O particulado foi incorporado em composições experimentais de 1:3 e 1:4 (cimento/agregado) e comparado com o traço de referência sem subproduto cerâmico. A avaliação do comportamento da mistura fresca foi realizada através dos testes Slump flow, L-box e V-funil. Posteriormente, a massa endurecida foi avaliada por ensaios de absorção de água e resistência à compressão. A superfície de fratura dos corpos de prova foi investigada por Microscopia Eletrônica de Varredura para compreensão do arranjo microestrutural. O estudo finalizou com a produção de blocos intertravados com três composições validadas, com substituições de 5%, 10% e 15% na mistura 1:3. Os resultados mostraram a viabilidade técnica de formulações com percentuais de substituição de até 15% na mistura 1:3 (cimento/agregado) e soma-se aos esforços que buscam uma produção mais limpa com foco no reaproveitamento de recursos que são desperdiçados.

Resumo em Inglês:

ABSTRACT This research evaluated the advantages and disadvantages of replacing sand with ceramic waste in self-compacting concrete for interlocking blocks production. The by-product was obtained in a warehouse of a commercial store dedicated to civil construction in the city of Maceió-Brazil and processed in ball mills in the laboratory. The material was characterized by X-Ray Fluorescence and X-ray Diffraction and its particle size was evaluated. The particulate was incorporated into experimental compositions of 1:3 and 1:4 (cement/aggregate) and compared with the reference mix without ceramic by-product. The evaluation of the behavior of fresh mix was carried out using the Slump flow, L-box and V funnel tests. Posteriorly, the hardened mass was evaluated by water absorption and compression resistance tests. The fracture surface of the specimens was investigated by Scanning Electron Microscopy for understanding the microstructural arrangement. The study ended with the production of interlocking blocks with three validated compositions, with substitutions of 5%, 10% and 15% in the 1:3 mix. The results showed the technical feasibility of formulations with replacement percentages of up to 15% in the 1:3 mix (cement/aggregate) and add to efforts that seek cleaner production with a focus on the reuse of resources that become waste.

Resumo em Inglês:

ABSTRACT This study evaluates titanium dioxide (TiO2), aluminum oxide (Al2O3), and hybrid coatings on lithium-ion battery electrodes, focusing on their implications for the Indian electric vehicle supply chain. Using Atomic Layer Deposition (ALD) and Chemical Vapor Deposition (CVD), coatings were applied to commercial-grade graphite and LiNiMnCoO2 (NMC) electrodes. The coatings were analyzed for ionic conductivity, chemical stability, mechanical reinforcement, thermal stability, and electrochemical performance using SEM, TEM, XRD, TGA, CV, EIS, and long-term cycling tests. Results show TiO2 coatings provide superior ionic conductivity (3.5 × 10–4 S/cm) but lower chemical stability. Al2O3 coatings, with an ionic conductivity of 1.8 × 10–4 S/cm, demonstrated excellent chemical stability and mechanical reinforcement (elastic modulus of 150 GPa). Hybrid coatings exhibited a balanced performance, with 80% capacity retention after 500 cycles at 0.5C and intermediate thermal stability. Conclusions indicate that TiO2 is suitable for high-rate applications, while Al2O3 is ideal for long-term stability. Hybrid coatings offer a promising solution by combining the strengths of both materials, enhancing battery performance, and supporting the development of efficient and reliable energy storage solutions for India’s electric vehicle industry.

Resumo em Português:

RESUMO Os aços maraging são aços especiais de ultra-alta resistência e alta tenacidade, mas, apesar de suas propriedades notáveis, suas aplicações ainda são limitadas devido ao seu alto custo de produção. O objetivo deste trabalho consiste em avaliar a relação entre a formação de precipitados e o teor de austenita revertida, correlacionando com a dureza e as alterações nas propriedades mecânicas relativas à tração do aço maraging 300 sob diferentes condições de tratamentos térmicos, para servir como parâmetro de análise no seu emprego em blindagens balísticas. Amostras de aço maraging 300 foram tratadas em 29 diferentes condições de envelhecimento e o comportamento de endurecimento por precipitação foi analisado empregando diferentes técnicas, como: ferritoscopia, ensaio de dureza nas situações como recebido e envelhecido, e ensaio de tração nas temperaturas de 440, 480 e 570 °C, a fim de verificar a influência da fase austenítica nas propriedades mecânicas. A influência do superenvelhecimento foi observada na amostra de 570 °C, resultando numa diminuição de aproximadamente 31% na resistência mecânica e um aumento em torno de 40% na ductilidade, em comparação com a amostra envelhecida a 440 °C, indicando uma melhora na tenacidade do material.

Resumo em Inglês:

ABSTRACT Maraging steels are special ultra-high-strength and high-tenacity steels, but despite their remarkable properties, their applications are still limited due to their high production cost. The aim of this work is to evaluate the relationship between the formation of precipitates and the content of reverted austenite, correlating with the hardness and changes in tensile mechanical properties in a class 300 maraging steel subjected to different heat treatment conditions, to serve as analysis parameter in its use in ballistic armor. Samples of maraging 300 steel were treated in 29 different aging conditions and the precipitation hardening behavior was analyzed using different techniques, such as: ferritoscopy, hardness test in as-received and aged situations, and tensile testing at temperatures of 440, 480 and 570 °C, in order to verify the influence of the austenitic phase on the mechanical properties. The influence of overaging was observed in the 570 °C sample, resulting in a decrease of approximately 31% in mechanical strength and an increase of around 40% in ductility, compared to the sample aged at 440 °C, indicating an improvement in the toughness of the material.

Resumo em Inglês:

ABSTRACT To study the damage evolution behavior and damage constitutive model of selective-laser-melted (SLMed) Ti6Al4V alloy under different heat treatment temperatures, tensile tests were conducted. The effect of heat treatment temperature on microstructure and mechanical properties of SLMed Ti6Al4V alloy is discussed. Elastic modulus was selected to characterize damage, and the damage evolution law of SLMed Ti6Al4V alloy was quantitatively analyzed, establishing the damage evolution equation. Based on the theory of continuous damage mechanics, the Ramberg-Osgood model was introduced to establish the damage constitutive model of SLMed Ti6Al4V alloy under different heat treatment temperatures. The results show that with increasing heat treatment temperature, the acicular α′ phase in the microstructure of SLMed Ti6Al4V alloy is gradually transformed into α + β phase, the α phase is gradually coarsened, the volume fraction of β phase gradually increased. The microhardness and tensile strength of the SLMed Ti6Al4V alloy decreased from 376.44 HV and 1171.5 MPa to 317.31 HV and 790.9 MPa, while elongation increased from 6.6% to 13.6% and then decreased to 11.1%. The critical strain in the as-deposited sample is 0.009, entering the rapid damage accumulation stage first, whereas heat-treated samples lag significantly. The error between model and experimental results is within 7%.

Resumo em Inglês:

ABSTRACT In this study, the reinforcement of reinforced concrete (RC) components with a combination of aramid and basalt fibers to enhance the overall structural performance and durability. In this empirical investigation, we meticulously assess the strength of concrete components both with and without the incorporation of fibers, while also scrutinizing the strengthening of concrete components exposed to the detrimental effects of fire. The concrete components under scrutiny encompass cubes, prism cylinders, and other specimens constructed from standard concrete, as well as concrete components enveloped with basalt fiber and aramid fiber. This research endeavor adopts the M20 mix for the concrete specimens, which are meticulously cast and cured in order to facilitate the subsequent testing of compressive strength (CS), flexural strength (FS), and split tensile strength (STS). The potency and fire-resistant properties of the standard concrete specimens are juxtaposed with those of the concrete specimens enveloped with basalt fiber and aramid fiber, which are then subjected to varying temperatures. Ultimately, the culmination of this project consists of the presentation of the findings and the comprehensive elucidation of the details derived from the aforementioned experiments.

Resumo em Inglês:

ABSTRACT This paper presents the feasibility of utilizing Wind Turbine Blade (WTB) wastes as an alternative for the natural aggregate in cement concrete. Three types of experimental investigations were conducted to assess the potential of WTB combined with natural aggregate in concrete. As preliminary investigation, porosity property of the WTB aggregate is determined by water absorption test. Similarly, toughness and impact resistance properties are verified by aggregate impact and crushing tests respectively. An attempt has been made to study the influence of waste WTB as a substitute for natural aggregates in concrete for M25 grade at replacement percentage of 10, 20, 30, 40, and 50. Mechanical properties of developed concrete are evaluated by compressive strength, flexural strength and split tensile strength tests. Based on the results, 20% WTB waste substituted concrete had 8.5%, 14.7%, and 8.9% higher compressive strength, split tensile strength, and flexural strength than conventional concrete. The strength increment in the developed concrete is confirmed through microstructural evaluation using SEM micrographs, XRD and FTIR. Based on the investigation-conducted use of WTBs seems to have prospective applications in concrete with economic and environmental benefits preventing the accumulation of landfills of WTBs paving way for sustainability.

Resumo em Inglês:

ABSTRACT The study uses a phase Doppler particle analyzer to experimentally investigate the influence of minimum quantity lubrication (MQL) parameters on the spray characteristics of vegetable oils in the MQL system. Droplet velocity and diameter of the Azadirachta Indica, Ceiba Pentandra, Madhuca Longifolia, and Calophyllum Inophyllum are measured by varying pressure levels, flow rate, and nozzle diameter. MQL system, Spray chamber system, and PDPA unit are the major systems in the PDPA system. MQL system supplies the oil as a mist in the spray chamber through the nozzle. At the same time, the PDPA unit measures the spray characteristics of the disintegrated oil using the Doppler effect. The oil droplet’s size decreased when the pressure increased, whereas it increased with the oil’s viscosity. The nozzle of 2 mm diameter reduced the droplet size while it increased for the 2.5 mm nozzle. The effect of the oil flow rate on spray characteristics was found to be insignificant. The results showed that lower-viscosity oils, ideal for machining, offer less resistance to disintegration and generate smaller droplets in the spray. Among all, the disintegration of oils is highly encouraged by pressure and nozzle diameter. In addition, suitable MQL system parameters can be identified for sustainable machining.

Resumo em Inglês:

ABSTRACT This study investigates the preparation and application of biochar-supported nanoscale zero-valent iron (nZVI@BC) for the removal of chlortetracycline (CTC) from water and soil. The nZVI@BC composite was synthesized via a modified co-precipitation method and characterized using XRD, SEM, N2 adsorption-desorption, and XPS techniques. The material exhibited enhanced surface area and porosity compared to unmodified biochar. Batch experiments were conducted to evaluate the adsorption and degradation kinetics of CTC in aqueous solutions, revealing rapid initial uptake and equilibrium within 4 hours. The effects of pH, temperature, and adsorbent dosage on CTC removal were examined. In soil matrices, nZVI@BC significantly improved CTC adsorption capacity, with adsorption behavior best described by the Langmuir isotherm model. Thermodynamic analysis indicated an endothermic and spontaneous adsorption process. The impact of nZVI@BC on CTC degradation in soil was assessed through a 14-day experiment, monitoring CTC and its metabolites epichlortetracycline (ECTC) and isochlortetracycline (ICTC). Results demonstrated enhanced degradation of CTC and its metabolites in nZVI@BC-modified soils. This study provides valuable insights into the potential of nZVI@BC as an effective material for remediation of antibiotic-contaminated water and soil environments, showcasing its dual functionality in adsorption and catalytic degradation.

Resumo em Inglês:

ABSTRACT This study examines the structural performance of a cold-formed steel (CFS) structural frame subjected to lateral loading. An experimental investigation was conducted on cold-formed steel frame. Structural building frames made of cold-formed steel structural members. The structural members (beams and columns) were selected for building the structural frame on the basis of optimized design considering factors such as ease of availability of section and adequate testing conditions. In this way, the channel section is used for columns provided with and without lips. Parameters such as load-carrying capacity, stiffness, and the load– deflection relationship were examined. Based on the results and discussion, the structural frame made with a lipped channel section was found to have high load carrying capacity and high stiffness compared with the other models.