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.

Resumo em Inglês:

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.

Resumo em Inglês:

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.

Resumo em Inglês:

ABSTRACT The objective of this work is to study the behavior of corrosion in reinforced concrete slabs from the point of view of geostatistics. To this end, measurements of electrochemical potentials (reinforcement corrosion potentials) were taken in regions of a reinforced concrete slab, which was divided into smaller areas of the same dimensions in the “x” and “y” directions, respectively. In order to make the study feasible, a sub-region of this slab was separated where the corrosive activity was already more aggressive and the variograms were calculated for the “x” and “y” directions, according to the distances from the measurement points. After a detailed analysis of the results and the creation of graphs for each axis, the equations that best fitted the curves were obtained, in particular the polynomial for the “x” direction and the logarithmic for the “y” direction. From the data obtained, it is possible to understand the spatial extent of the problem, identify the corrosion bands in which each region of the structure studied is located and know the zone of influence of the sub-region used for analysis. The results can be used to choose the best technique for mitigating and combating slab corrosion, as well as for future work.

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.