Search Results (2,991)

This study presents a novel application of SVX, a recombinant spider silk-inspired biopolymer, for advanced haircare formulations, designed to protect bleached and color-treated hair. Two SVX-based treatments—a multifunctional leave-on serum and a post-color booster—were developed to address key challenges: color fading, heat damage, and moisture loss. Under simulated oxidative, thermal, and environmental stress conditions, SVX formulations demonstrated significantly improved performance compared to benchmark products. SVX-treated hair exhibited a substantial reduction in color change (ΔE reduced from 5.2 ± 1.1 to 2.1 ± 0.6), retained mechanical strength after intense heat exposure (>90% tensile strength vs. 64% in controls), and showed a marked increase in hydration (>84% moisture retention vs. 56% in untreated hair). The booster treatment further enhanced cuticle sealing and post-color recovery without altering dye intensity. SVX forms a protective, proteinaceous network on the hair surface, reinforcing the fiber structure and maintaining moisture. Its sustainable, biodegradable, and vegan profile supports its use in next-generation cosmetic innovations. These results position SVX as a powerful, multifunctional ingredient for high-performance and eco-conscious haircare applications. Full article

Composite geopolymer concrete (CGPC), is receiving growing attention in the construction sector for its sustainable nature, environmental benefits, and its valuable role in promoting efficient waste utilization. The strategic incorporation of reinforcing fibers into geopolymer concrete (GPC) matrices is critical for enhancing mechanical performance and meeting the durability requirements of high-performance construction applications. Although substantial research has focused on strength enhancement of fiber-reinforced geopolymer concrete (FGPC) individually, it has neglected practical considerations such as energy use for curing and life-cycle assessments. Thus, this study investigates the cost-effective aspects of FGPC cured under different regimes. Different cementitious binders were incorporated, i.e., fly ash (FA) and ground granulated blast-furnace slag (GGBS), in addition to alkaline activators (a combination of sodium hydroxide and sodium silicate), hooked-end steel fibers (HESFs), basalt fibers (BFs), and polypropylene fibers (PPFs), as well as aggregates (gravel and sand). The effect of different geopolymer-based materials, reinforcing fibers, and different curing regimes on the mechanical, durability, and economic performance were analyzed. Results showed that the applied thermal curing regimes (oven curing or steam curing) had a considerable impact on durability performance, compressive strength, and flexural strength development, especially for GPC mixes involving high FA content. Cost analysis outcomes suggested that the most affordable option is GPCM1 (100% FA without fibers), but it demonstrates low strength under ambient curing conditions; RGCM4 (100% GGBS and 0.75% HESF) provided the best strength and durability option but at higher material cost; RGCM7 (50% FA, 50% GGBS, and 0.75% HSF) exhibited a balanced choice since it offer satisfied strength and durability performance with moderate cost compared to other options. Full article

As a support material for mine roadways, shotcrete (SC) exhibits performance limitations in extreme deep-mining environments characterized by high stress and water seepage. Polyoxymethylene (POM) fiber, with its properties of high strength, high modulus, and corrosion resistance, holds potential for application in surrounding rock support of deep roadways. To investigate the effect of POM fiber on the flexural performance of shotcrete, four-point bending tests were conducted on fiber-reinforced concrete specimens with different fiber lengths and dosages. Combined with ABAQUS numerical simulation, damage simulation analysis was performed on each group of specimens, and the stress propagation state of the fibers was tracked. The results show that the flexural strength of polyoxymethylene fiber shotcrete (PFS) increases with the increase in fiber length and dosage, and the influence of fiber dosage is more significant. POM fiber can effectively inhibit the crack development of shotcrete, enhancing its crack resistance and residual strength. The load-deflection curves indicate that PFS exhibits excellent fracture toughness, with the P9L42 group showing the highest flexural strength improvement, reaching an increase of 94%. The numerical simulation results are in good agreement with the experimental conditions, accurately reflecting the damage state and load-deflection response of each group of concrete specimens. Based on the above research, POM fiber is more conducive to meeting the stability requirements of roadway surrounding rock support, providing a scientific basis for the application of PFS in mine roadway surrounding rock support. Full article

Fused filament fabrication of thermoplastic composites, despite its recyclability, increased strength, and efficiency, faces structural limitations under elevated temperatures. The literature on heat treatments for improving the thermal resilience of accessible 3D printed composites is limited. Therefore, this study comprehensively presents the efficacy of annealing on carbon fiber reinforced polyamide (PAHT-CF). The methodology includes uniaxial tensile testing of 200 samples across a wide temperature range (25–150 °C) and five different infill orientations, annealed as per the Technical Data Sheet (80 °C, 12 h). Scanning electron microscopy (SEM) of the fracture surfaces revealed the microstructural changes responsible for the improved properties after annealing. At 25 °C, annealing led to a 50% strength increase (63.88 MPa) and a 70% lower strain (2.65%). At 150 °C, the material maintained a 17.5% strength advantage (23.62 MPa) and a 17.5% reduction in strain (12.67%). The 0°, 90°, and 0/90° orientations exhibited the highest improvements, while the remainder displayed lower strengths and higher deformation beyond the glass transition temperature (70 °C). Overall, annealed PAHT-CF demonstrates high-temperature resilience, comparable to previously analyzed materials like carbon fiber reinforced polyether–ether–ketone (PEEK-CF). This makes it a potentially accessible alternative for the aerospace and automotive sectors. However, practical applications must consider the trade-off between its enhanced mechanical properties and the increased lead time from annealing. Full article

Fiber-reinforced polymer (FRP) composites, particularly glass fiber-reinforced polymer (GFRP), are increasingly utilized in civil engineering due to their high strength-to-weight ratio, corrosion resistance, and environmental sustainability compared to steel. Shear connectors in FRP–concrete hybrid beams are critical for effective load transfer, yet their behavior under static loads remains underexplored. This study aims to investigate the shear strength, stiffness, and failure modes of GFRP, CFRP, AFRP, and stainless-steel shear connectors in FRP–concrete hybrid beams through a comprehensive parametric analysis, addressing gaps in material optimization, bolt configuration, and design guidelines. A validated finite element model in Abaqus was employed to simulate push-out tests based on experimental data. The parameters analyzed included shear connector material (GFRP, CFRP, AFRP, and stainless steel), bolt diameter (16–30 mm), number of bolts (1–6), longitudinal spacing (60–120 mm), embedment length (40–70 mm), and concrete compressive strength (30–70 MPa). Shear load–slip (P-S) curves, ultimate shear load (P), secant stiffness (K₁), and failure modes were evaluated. CFRP bolts exhibited the highest shear capacity, 26.50% greater than stainless steel, with failure dominated by flange bearing, like AFRP and stainless steel, while GFRP bolts failed by shear failure of bolt shanks. Shear capacity increased by 90.60%, with bolt diameter from 16 mm to 30 mm, shifting failure from bolt shank to concrete splitting. Multi-bolt configurations reduced per-bolt shear capacity by up to 15.00% due to uneven load distribution. Larger bolt spacing improved per-bolt shear capacity by 9.48% from 60 mm (3d) to 120 mm (6d). However, in beams, larger spacing reduced the total number of bolts, decreasing overall shear resistance and the degree of shear connection. Higher embedment lengths (he/d ≥ 3.0) mitigated pry-out failure, with shear capacity increasing by 33.59% from 40 mm to 70 mm embedment. Increasing concrete strength from 30 MPa to 70 MPa enhanced shear capacity by 22.07%, shifting the failure mode from concrete splitting to bolt shank shear. The study highlights the critical influence of bolt material, diameter, number, spacing, embedment length, and concrete strength on shear behavior. These findings support the development of FRP-specific design models, enhancing the reliability and sustainability of FRP–concrete hybrid systems. Full article

To address the problem of corrosion, glass fiber-reinforced polymer (GFRP) bars have been introduced as a viable alternative to conventional steel reinforcement in concrete structures. While extensive research has been conducted on the flexural behavior of RC beams reinforced with steel and GFRP bars over both normal-term and long-term periods, studies focusing on fresh concrete beams are almost non-existent. Consequently, this research investigates the impact of steel and GFRP longitudinal reinforcement, as well as the influence of varying concrete compressive strengths, on the flexural behavior of RC beams. The study employs 3-point bending experiments and machine learning (ML) predictive analyses. Specifically, the short-term (fresh) concrete reinforcement compatibility and the effects of steel and GFRP bar reinforcements on beam flexural behavior were examined across three concrete compressive strength categories: low (C25), moderate (C35), and high (C50). A notable contribution of this research is the application of different ML regression models, utilizing Python’s library, for deflection prediction of RC beams. The failure mechanisms of the beams under static loading conditions were analyzed, revealing that composite bar RC beams failed through flexural cracking and demonstrated ductile behavior, whereas steel bar RC beams exhibited brittle failure characterized by shear cracks and sudden failure modes. The ML regression models successfully predicted the deflection values of RC beams under ultimate loads, achieving an average accuracy of 91.3%, which was deemed highly satisfactory. Among the 18 beams tested, the highest ultimate load was obtained for the SC50-1 beam at 87.46 kN. In contrast, while the steel-reinforced beams exhibited higher load-bearing capacities, it was observed that the GFRP-reinforced beams showed greater deflection and ductility, particularly in beams with low and medium concrete strengths. Based on these findings, it is recommended that the Gradient Boosting Regressor, an AI regression model, be utilized to guide researchers in evaluating the load-carrying and bending capacity of structural beam elements. Full article

This paper proposes a multi-objective optimization method that integrates deep neural networks (DNN) with gray relational analysis (GRA) to optimize lay-up configurations for carbon fiber-reinforced plastic (CFRP) automotive components. Specifically, a lab-scale CFRP B-pillar structure was investigated to simultaneously maximize structural strength and failure safety. A DNN surrogate model was trained using finite element simulations of 2000 random stacking sequences to achieve high predictive accuracy. The trained model was then used to evaluate all possible lay-up combinations to derive Pareto optimal solutions. Gray relational analysis was subsequently employed to select the final optimal configurations based on designer preferences. The selected lay-up designs demonstrated improvements in both strength and failure safety. To validate the proposed framework, laboratory-scale CFRP B-pillar was fabricated using a prepreg compression molding process and subjected to bending tests. The experimental results confirmed an error below 5% and failure trends consistent with the simulation results, thereby validating the reliability of the proposed method. The proposed DNN-GRA approach enables efficient multi-objective optimization with reduced computational effort and flexibility in reflecting different engineering priorities. Full article

Large-format additive manufacturing (LFAM) is an enabling manufacturing technology capable of producing large parts with highly complex geometries for a wide variety of applications, including automotive, infrastructure/construction, and aerospace mold and tooling. In the past decade, the LFAM industry has seen widespread use of bio-based, glass, and/or carbon fiber reinforced thermoplastic composites which, when printed, serve as a lower-cost alternative to metallic parts. One of the highest-volume materials utilized by the industry is carbon fiber (CF)-filled polycarbonate (PC), which in out-of-autoclave applications can achieve comparable mechanical performance to metal at a significantly lower cost. Previous work has shown that if this material is recovered at various points throughout the manufacturing process for both the lab and pilot scale, it can be mechanically recycled with minimal impacts on the functional performance and printability of the material while significantly reducing the feedstock costs. End-of-life (EOL) CF-PC components were processed through industrial shredding, melt compounding, and LFAM equipment, followed by evaluation of the second-life material properties. Experimental assessments included quantitative analysis of fiber length attrition, polymer molecular weight degradation using gel permeation chromatography (GPC), density changes via pycnometry, thermal performance using dynamic mechanical analysis (DMA), and mechanical performance (tensile properties) in both the X- and Z-directions. Results demonstrated a 24.6% reduction in average fiber length compared to virgin prints, accompanied by a 21% decrease in X-direction tensile strength and a 39% reduction in tensile modulus. Despite these reductions, Z-direction tensile modulus improved by 4%, density increased by 6.8%, and heat deflection temperature (HDT) under high stress retained over 97% of its original value. These findings underscore the potential for integrating mechanically recycled CF-PC into industrial LFAM applications while highlighting the need for technological innovations to mitigate fiber degradation and enhance material performance for broader adoption. This critical step toward circular material practices in LFAM offers a pathway to reducing feedstock costs and environmental impact while maintaining functional performance in industrial applications. Full article

This study investigates an alternative methodology for incorporating polymeric and steel fibers into concrete. Conventional reinforcement approaches often require complex application techniques and face industrial limitations. In contrast, the present work evaluates the use of short, discontinuous fibers—commercial polypropylene fibers (PFRC), polypropylene fiber braid (PFBRC) and steel fibers (SFRC)—which enable improved dispersion, ease of mixing and potential mechanical benefits. The fibers were randomly oriented and evenly distributed within the cementitious matrix. Mechanical performance was assessed through four-point bending tests combined with displacement measurements, acoustic emission analysis and uniaxial compression tests, while scanning electron microscopy (SEM) confirmed fiber–matrix interaction and fragment retention. The results demonstrated significant improvements, with compressive strength exceeding that of unreinforced concrete, while hybrid fiber systems provided enhanced crack resistance and post-cracking stability. Overall, the findings highlight that the integration of discontinuous fibers may provide tangible mechanical advantages, potentially outweighing the structural benefits of continuous reinforcing bars in applications requiring high strength and reliable mechanical performance. Full article

This study explores the potential of a bio-based thermosetting adhesive system incorporating recycled fillers to enhance structural bonding applications while promoting sustainability. Diglycidylether of vanillyl alcohol (DGEVA) was selected as the resin matrix due to its favorable thermomechanical properties and low moisture absorption. To improve mechanical performance and support circular economy principles, recycled carbon fibers (RCFs) and mineral wool (MW) were integrated into the adhesive formulation in varying proportions (10, 30, and 50 phr). A cationic thermal initiator, ytterbium (III) trifluoromethanesulfonate (YTT), was used to permit polymerization. Comprehensive characterization was performed to assess the curing behavior, thermal stability, and mechanical performance of the adhesive. FTIR spectroscopy monitored the polymerization process, while DSC and dynamic DSC provided insights into reaction kinetics, including activation energy, and curing rates. The mechanical and thermomechanical properties were evaluated using dynamic mechanical thermal analysis (DMTA) and shear lap testing on bonded joints. Additionally, SEM imaging was employed to examine fillers’ morphology and joint interfaces. The results indicated that increasing filler content slowed polymerization and raised activation energy but still permitted high conversion rates. Both RCF- and MW-containing formulations exhibited improved stiffness and adhesion strength, particularly in CMC joints. These findings suggest that DGEVA-based adhesives reinforced with recycled fillers offer a viable and sustainable alternative for structural bonding, contributing to waste valorization and green material development in engineering applications. Full article

Natural fibers are replacing synthetic fibers and are used to develop different useful composite products due to their environmental advantages. To fabricate high-performance composites, high-quality natural fibers are essential. Fiber quality largely depends on the extraction method and subsequent treatment. In this study, fibers were extracted using both machine and manual methods, treated with 5% NaOH, and used at a 30:70 fiber-to-matrix volume ratio to fabricate composite laminates. Key properties such as tensile, flexural, and impact strength, water absorption, elemental composition, and morphological structure were analyzed. When comparing the untreated fiber composites, the machine-extracted samples exhibited a 6.7% increase in tensile strength and a 7.06% increase in flexural strength over those extracted manually. For treated fiber composites, the machine-extracted samples showed improvements in tensile, flexural, and impact strengths of 19.82%, 19.38%, and 26.59%, respectively, compared to those extracted manually. These enhancements indicate that machine extraction provides fibers with better structural integrity and consistency, contributing to stronger fiber–matrix bonding. The machine-extracted treated composites showed reduced water absorption and smaller fiber diameters, indicating that machine extraction was more effective in removing impurities from the fibers. Scanning electron microscopy (SEM) confirmed improved fiber–matrix interfacial bonding in the machine-extracted composites, which also exhibited better water resistance. This study highlights that fiber extraction and treatment significantly influence the mechanical, physical, and morphological properties of natural fiber composites, as verified through SEM, EDS, and universal testing machine (UTM) analysis. Full article

This study explores the mechanical behavior of concrete reinforced with recycled carbon fiber (RCF) and incorporating modified basic oxygen furnace slag (MBOF) as a sustainable aggregate. The RCF was recovered from waste carbon fiber-reinforced polymer (CFRP) bicycle rims via microwave-assisted pyrolysis (MAP), while MBOF was produced by water-based treatment of hot BOF slag. The experimental program included compressive, splitting tensile, and flexural strength tests, as well as impact resistance and stress-reversal Split Hopkinson Pressure Bar (SRSHPB) tests. The effects of RCF length (6 mm and 12 mm) on the mechanical performance of MBOF-based concrete were systematically examined. The results demonstrated that incorporating MBOF as aggregate, combined with the addition of RCF, significantly enhanced both static strength and dynamic impact resistance. Compared with fiber-free MBOF concrete, the incorporation of 6 mm and 12 mm RCF increased compressive strength by 3.03% and 13.77%, flexural strength by 14.50% and 19.74%, and splitting tensile strength by 2.60% and 25.84%, respectively. Similarly, the impact number increased by approximately 6.81 and 12.67 times for the 6 mm and 12 mm RCF specimens, respectively, relative to the fiber-free specimen. Furthermore, the SRSHPB test results indicated that MBOF concrete reinforced with 12 mm RCF exhibited greater dynamic compressive strength than that reinforced with 6 mm RCF. Overall, MBOF concrete incorporating 12 mm RCF demonstrated superior performance to its 6 mm counterpart across all evaluated strength parameters. These findings highlight the potential of utilizing metallurgical and composite waste to develop high-performance, sustainable concrete materials. Full article

Ordinary concrete exhibits inherent brittleness, which restricts its deformation capacity and durability under extreme loading conditions. Engineered cementitious composites (ECC) have been developed to address these limitations; however, conventional ECC often suffers from relatively low compressive strength, limiting its use in demanding structural applications. To overcome this drawback, high-strength ECC (HS-ECC) was prepared by incorporating high-volume mineral admixtures and three types of synthetic fibers-polypropylene (PP), polyethylene (PE), and polyvinyl alcohol (PVA). This study aimed to investigate the influence of fiber type and dosage on the flexural behavior of HS-ECC and to propose a toughness evaluation framework better suited to its strain-hardening characteristics. A comprehensive experimental program, including compressive and four-point bending tests, was conducted to evaluate failure modes, flexural performance, and post-cracking behavior. Results showed that PE fibers significantly enhanced flexural strength and toughness, PP fibers provided superior deformability at higher dosages, while PVA fibers tended to fracture due to strong matrix bonding, limiting their effectiveness in high-strength matrices. Based on the observed load–deflection responses, a physically meaningful flexural toughness evaluation method was developed, which reliably captured elastic, hardening, and softening stages of HS-ECC. The findings not only clarify the role of different fiber types in HS-ECC but also offer a new evaluation approach that can guide fiber selection and mix design for structural applications. Full article

This study presents a systematic evaluation of frost resistance in concrete modified with nano-alumina (NA, 1 wt%), nano-silica (NS, 2 wt%), and polypropylene fiber (PP, 0.2 wt%) through accelerated freeze–thaw testing. The investigation employed a comparative experimental approach, subjecting specimens with optimal mechanical dosages to 300 freeze–thaw cycles. The degradation was quantitatively assessed by monitoring the evolution of mass loss, dynamic elastic modulus, and compressive strength. Results reveal that PP-modified concrete demonstrates optimal performance, retaining 70% of its dynamic elastic modulus (vs. 68% for NA and 64% for control, and failing at 58% for NS after 200 cycles) and exhibiting only 9.3% compressive strength loss (vs. 13.9% for NA and 27.3% for control, and 43.6% for NS). These findings establish PP as the most effective modifier, offering both superior frost resistance (300+ cycle durability) and practical advantages (simpler processing, lower cost). The results provide a scientific basis for designing high-performance concrete in cold regions, with particular relevance to infrastructure requiring long-term durability under cyclic freezing conditions. Full article

Carbon-fiber-reinforced silicon carbide (C/SiC) composite materials, as a kind of composite material with the characteristics of ceramics, have the following characteristics: high strength, high stiffness, low density, high temperature resistance, and high corrosion resistance. These characteristics make them widely applicable in aerospace, defense, automotive, and other high-performance industries. However, because of their anisotropy and inherent brittleness, ceramic-based composites are still difficult to process using conventional processing techniques. In this study, a technique of ultrasonic vibration-assisted micro-electrical discharge machining (micro-EDM) for the precise machining of two-dimensional (2D) C/SiC composites was proposed. The research mainly focused on an investigation of the material removal mechanism of C/SiC composites under ultrasonic vibration-assisted micro-EDM conditions. The erosion process was found to involve melting and vaporization of the SiC matrix, whereas the carbon fibers were removed by fragmentation and localized melting. In order to assess the effects of various process parameters on the material removal rate (MRR), single-factor experiments were performed initially. Afterwards, response surface methodology was used to optimize the MRR of C/SiC composites during ultrasonic vibration-assisted micro-EDM. A Plackett–Burman (PB) design was used to determine the parameters that have a significant effect on MRR. Based on these results, the optimum parameter range was obtained using the method of steepest ascent. Finally, a Box–Behnken design was used to determine the best machining parameters for improved performance. Full article