Journal of Composites Science

With Aligned Formable Fibre Technology (AFFT^™), fibers are reformatted into highly oriented epoxy prepreg tapes, enabling the structural reuse of recycled composite waste. The present study investigates whether discontinuous fiber laminates produced with AFFT^™ can be characterized and optimized with the same finite-element workflows long established for continuous fiber composites and whether the resulting structures meet demanding stiffness targets. Initially, various manufacturing methods were adopted, including vacuum bagging, compression molding at 7 bar to simulate autoclave conditions, and compression molding at 90 bar, comprising the three most reasonable manufacturing processes for AFFT^™ laminates. Experimentally measured orthotropic properties were introduced into a finite-element model representing an idealized bicycle top tube, which was chosen as a case study. A genetic algorithm screened candidate stacking sequences, minimizing the combined bending-and-torsion deflection. The best lay-ups reduced deformation by more than 30% compared to a quasi-isotropic baseline, showing that well-oriented short fibers can significantly contribute to the stiffness of composites. Tubes produced with the optimized lay-up were tested in three-point bending tests, and the measured stiffness matched simulations within 5%. These results confirm a key point for sustainable engineering: despite the absence of continuous fibers, conventional simulation strategies accurately predict the performance of AFFT^™ laminates and can be used as the basis for effective genetic optimization. This validation is significant: it enables the design of stiff, high-performance structures from recycled materials using established, cost-effective methods. By proving that optimization strategies developed for traditional continuous fiber composites apply to AFFT^™, this study offers a trusted and accessible pathway to scale circular economy solutions in next-generation composite products. Full article

Natural fibre hybrid composites have gained attention as cleaner alternatives to synthetic glass fibre systems due to their renewable feedstocks and inherent density advantage. However, moisture ingress degrades fibre–matrix integrity and mechanical performance, making durability a critical design constraint. This study systematically investigates the water absorption kinetics and post-immersion mechanical property retention in ramie–flax/epoxy hybrid composites across four fibre loadings (10–40 wt.%), with the ramie-to-flax weight ratio fixed at 1:1 in all formulations. Tensile, flexural, and impact properties were evaluated under dry and saturated conditions; Fickian diffusion kinetics were analysed to quantify moisture transport parameters; and fracture surfaces were examined by SEM. A density-based material efficiency analysis quantified the lightweighting benefit relative to equivalent synthetic glass/epoxy composites. Water absorption increased monotonically with fibre content; all formulations reached equilibrium after approximately 120 h. The 30 wt.% composite achieved dry-state tensile, flexural, and impact strengths of ca.49 MPa, ca.58 MPa, and 2.82 kJ/m² respectively, retaining ca.78%, ca.69%, and ca.82% after full saturation, superior to all other loadings. These results establish 30 wt.% as the optimal fibre loading for moisture-exposed semi-structural applications, supporting the adoption of ramie–flax composites within a cleaner manufacturing framework. Full article

The growing demand for lightweight and cost-effective vehicular armor systems has driven the development of hybrid multilayer architectures capable of improving ballistic resistance while reducing structural mass. This study evaluates the ballistic performance of a functionally graded aluminum–Kevlar–cabuya fiber composite system designed for vehicle door protection. A combined experimental–numerical framework was implemented, integrating ballistic testing according to NIJ 0108.01 and STANAG 4569 Level 1 standards with explicit dynamic finite element modeling based on the Johnson–Cook constitutive formulation for AA5083-H32. The multilayer configuration (25 mm aluminum/15 mm Kevlar 29/15 mm treated cabuya composite) successfully resisted 9 × 19 mm and 5.56 × 45 mm FMJ threats without complete perforation. Numerical simulations predicted a maximum back-face deformation of 52.75 mm under 9 mm impact, showing strong agreement with the experimental measurements (mean ± SD, n = 3). Post-impact microstructural analysis revealed a sequential energy dissipation mechanism governed by plastic deformation of the aluminum layer, Kevlar fibrillation and fragment retention, and controlled micro-cracking within the treated cabuya backing layer. With an areal density of 140.87 kg/m², the system achieved a 19% weight reduction compared with conventional steel-based solutions. These results demonstrate the structural-scale feasibility of integrating treated cabuya fiber composites as active energy redistribution layers in certified hybrid vehicular armor systems. Full article

This paper investigates the AWJ machinability of Hibiscus Rosa-Sinensis/carbon nanotube (CNT) fiber/epoxy-based hybrid composites by analyzing key machinability metrics such as kerf width (KW), material removal rate (MRR), and surface roughness (Ra). Various process parameters including CNT weight percentage, CNT diameter, stand-off distance, and traverse speed have been varied to optimize the machining performance. Experimental analysis suggested that increasing the CNT weight percentage significantly enhanced material hardness, thereby reducing both the MRR and surface roughness. Moreover, adjusting the stand-off distance and traverse speed further improved the machinability of the composite. ANOVA results highlighted that CNT weight percentage was a significant factor, accounting for 94.17% of the variation in MRR and 93.72% of the variation in surface finish, while the stand-off distance influenced 87.03% of the variation in kerf width. Additionally, response surface methodology (RSM) was utilized to develop predictive models that estimated KW, MRR, and Ra with error rates of 2.95%, 2.23%, and 5.65%, respectively. These insights offer a valuable framework for tailoring the AWJ process to achieve optimal machining outcomes in HRS/CNT/epoxy composite materials Full article

Properties of composite materials with polymer matrix and inorganic filler are affected by preparation methods and starting components’ properties. For example, filler powder particle size distribution, phase composition and presence/absence of dopants can greatly affect properties of resulting composites. The present research attempts to clarify the influence of synthetic CaCO₃ powder properties on alginate/CaCO₃ composite material preparation process. Composite materials in the form of granules, networks and films were created from suspensions of synthetic powders of calcium carbonates CaCO₃ in aqueous solutions of sodium alginate. Powders of calcium carbonates CaCO₃ were synthesized from 0.5 M aqueous solutions of calcium chloride CaCl₂ and aqueous solutions of potassium K₂CO₃ (at molar ratio Ca/CO₃ = 1), sodium Na₂CO₃ (at molar ratio Ca/CO₃ = 1), and ammonium (NH₄)₂CO₃ (at molar ratios Ca/CO₃ = 1 and Ca/CO₃ = 0.5) carbonates. Phase composition of powder synthesized from CaCl₂ and K₂CO₃ was presented by calcite. Phase composition of powders synthesized from other soluble carbonates included calcite and vaterite. The powder preparation protocol excluded the stage of synthesized powder washing for by-product removal. This preparation protocol provided preservation of reaction by-product in the synthesized powder at a very low level. The presence of NH₄Cl as a reaction by-product even in small quantities can be taken as a reason for visually observed subsequences of cross-linking reaction at the stage of suspensions preparation. Aqueous solution of sodium alginate and suspensions containing powders synthesized from potassium K₂CO₃ and sodium Na₂CO₃ carbonates demonstrated similar dependence of viscosities from shear rate. The presence of (NH₄)₂CO₃ in the powder synthesized at molar ratio Ca/CO₃ = 0.5 was the reason for the lower viscosity of the suspension in comparison with suspensions loaded with powders containing KCl, NaCl and (NH₄)₂Cl as reaction by-products due to decomposition of unstable (NH₄)₂CO₃ and gas phase formation. The presence of (NH₄)₂Cl in the powder synthesized at molar ratio Ca/CO₃ = 1 in contrast was a reason for the highest viscosity suspension in comparison with those under investigation. Additionally, (NH₄)₂Cl presence in synthetic powders shows the ability to facilitate partial dissolution of CaCO₃ providing a higher concentration of Ca²⁺ cations at the stage of suspension preparation, thus aiding the cross-linking process of alginate hydrogel. Granules, meshes and films were created via interaction of suspensions of calcium carbonates CaCO₃ in aqueous solutions of sodium alginate with 0.25 M aqueous solutions of calcium chloride CaCl₂ to provide the formation of matrix of composites via Ca-crosslinking of sodium alginate followed by washing and freeze drying under deep vacuum. The created composite materials in the form of granules, meshes and films based on Ca-cross-linked alginate and powders of synthetic calcium carbonate can be recommended for skin wound and bone defect treatment and drug delivery carriers. Full article

The integration of Artificial Intelligence (AI) into the design, manufacturing, and lifecycle management of Composite Overwrapped Pressure Vessels (COPVs) is transforming the pathway toward autonomous and adaptive composite systems. This paper presents a comprehensive review and roadmap for AI-enabled COPVs development, bridging materials design, process optimisation, and predictive maintenance. The study synthesises over a decade of research on data-driven composite manufacturing, combining technology intelligence, PESTEL-SWOT environmental assessment, and cross-sectoral analysis of industrial and academic advances. A unified workflow is proposed to illustrate AI integration across the COPVs lifecycle, highlighting data feedback loops for continuous optimisation through digital twins and intelligent process control. Structural Health Monitoring (SHM) plays a central role in this ecosystem by providing real-time high-fidelity data on damage evolution and environmental interactions in COPVs. Through embedded sensing technologies such as fibre optic sensors and acoustic emission systems, SHM enhances digital twin fidelity, supports AI-based anomaly detection, and strengthens model validation in safety-critical hydrogen storage applications. Critical challenges are identified, including limited hydrogen-exposure datasets, lack of real-time adaptability, explainability in safety-critical design, and sustainability of AI-intensive workflows. These challenges highlight the need for tighter SHM-AI integration to enable reliable condition assessment and prognostics under multi-physics loading conditions. Based on these findings, the paper outlines actionable research directions to enable reliable, transparent, and sustainable AI adoption in composite manufacturing under the Industry 4.0 and hydrogen-economy paradigms. Full article

Composite materials are commonly employed because of their superior mechanical and electrical properties, as well as their lower density compared to metals. In this research, ceramic waste from the Casablanca region (Morocco) was incorporated into a composite material by combining it with finely ground ceramic fragments (CB) in an unsaturated polymer (UP) resin. The study objectives include the characterization of ceramic waste, evaluation of the mechanical stiffness, influenced by CB content and specimen thickness, and the assessment of its hydric behavior and erosion resistance in aggressive chemical environments. This valorization approach includes a baseline assessment of unmodified ceramic waste and UP’s compatibility and systematic documentation of geometry-dependent stiffness in short-cylinder compression tests. Several methods were used to characterize the material, including XRD, optical microscopy, FTIR-ATR, erosion testing, hydric behavior analysis, surface area measurement, and Young’s modulus. The results showed increased tensile strength and stiffness compared to the starting materials through the evolution of Young’s modulus, demonstrating the enhanced mechanical quality of the composite. Additionally, the material properties changed with the CB content and thickness of the sample, which indicated the potential for optimization. These findings advocate for the reuse of Moroccan industrial ceramic waste as a viable mineral filler for semi-structural polymer composites, supporting the circular economy, environmental sustainability, and public health. Full article

In this study, rice-husk fiber (RHF) extracted via alkali hydrolysis was used as a reinforcing material (0–10 wt%) in a pectin-sodium alginate (PE/SA) matrix to develop biofilms by the casting method. These biofilms were characterized by using FTIR, XRD, TGA, and DSC. The thickness, moisture content, water solubility, swelling behavior, water-contact angle, water-vapor permeability, optical transparency, and mechanical properties of biofilms were investigated. It was observed that the PE/SA/RHF film loaded with 5% RHF had better visual attributes, and a further increase in reinforcement was not found to be as favorable. The addition of 10 wt% RHF significantly enhanced the thickness from 0.094 to 0.127 mm, water solubility from 49.25 to 56.13%, water-contact angle from 48.4 to 62.6°, and tensile strength from 4.17 to 10.23 MPa. However, decreases in water-vapor permeability from 1.94 × 10⁻⁹ to 1.32 × 10⁻⁹ g·m⁻¹·Pa⁻¹·s⁻¹ and in elongation at break from 19.24 to 2.87% were observed in the biofilms. Structurally, FTIR confirmed intermolecular hydrogen bonding between components. XRD revealed that the films remained predominantly amorphous, without significant crystalline alterations. Furthermore, thermal stability improved with the addition of RHF. Finally, these PE/SA/RHF composite films may be potential eco-friendly biodegradable packaging candidates for food industry applications. Full article

This paper presents an experimental and numerical study on the effect of steel fiber distribution on the flexural behavior of self-compacting mortars (FRSCMs). Six FRSCM mixtures were modeled in ABAQUS as prismatic specimens (40 × 40 × 160 mm³) subjected to static three-point bending. The methodology involved two steps: (i) preparation of six mortar variants composed of three layers with different hooked steel fiber dosages (20, 30, and 40 kg/m³ for M20, M30, and M40) assembled in various configurations to study fiber distribution effects; (ii) numerical modeling of prismatic specimens in ABAQUS, using structured meshing with C3D8R hexahedral elements. Each layer was meshed separately with aligned nodes to ensure proper assembly. Our results highlight the strong influence of fiber distribution: despite identical fiber content (90 kg/m³ of hooked steel fibers), flexural strength varied across beam configurations. Layered casting led to an increase in flexural strength of up to 71.83% compared to the reference. The numerical predictions closely matched the experimental results, with relative errors ranging from 1% to 8.13% for most variants, demonstrating the reliability of the model. The larger discrepancies observed for specimens M324 and M342 are attributed to the limitation of the study to the elastic domain, as damage and plasticity effects were not included in the simulations. The distribution and orientation of fibers (particularly steel fibers) in a cementitious matrix, namely concrete or cement mortar, has been the subject of several studies aimed at determining the best mechanical performance of fiber-reinforced concrete. The proposed modeling approach of bending mechanical behavior allows us to predict the effects of fiber distribution in fluid mortars and reinforced self-compacting mortars, thereby reducing the need for extensive experimental testing. It also represents a significant improvement over existing approaches reported in the literature. Full article

The modification of road bitumen using micro-sized carbonaceous materials offers a promising route to enhance pavement performance; however, the influence of microdispersed coke derived from coal and petroleum sources has not been sufficiently clarified. In this study, coal and petroleum coke from Pavlodar Petrochemical Plant LLC (Pavlodar, Kazakhstan) were mechanochemically activated and used as the modifiers for BND 100/130 bitumen, produced by Asphaltbeton 1 LLC (Almaty, Kazakhstan). X-ray diffraction and scanning electron microscopy were used to determine the structure and morphology of the resulting coke powders. Standard tests and the Superpave Multiple Stress Creep and Recovery (MSCR) methodology were used to determine the physico-mechanical and rheological properties of the modified binders. Microdispersed granular coke powders produced after mechanochemical activation had a minimum average particle diameter of 8.28 µm (petroleum coke) and 16.64 µm (coal coke), and were mainly an amorphous carbon phase with traces of graphite. Addition of 1 wt.% microdispersed coke resulted in better performance of binder and an enhancement in grades of BND 100/130 to BND 70/100, in line with ST RK 1373-2013. MSCR testing showed that Jnr_3.2 is between 2.0–3.0 kPa⁻¹, which is in the S category of AASHTO M 332-20. This study showed how micro-sized coal and petroleum coke can be effectively used as a high-carbon modifier in bitumen, which reflects the possibility of their practical use in asphalt pavements that are subjected to normal traffic conditions. Full article

Thin wall composite fan blades in aircraft engines demand designs that ensure structural integrity under operational loads while resisting foreign object damage and bird strikes. This study presents a finite element investigation of thin wall composite blades with metal leading edge caps, modeled through parametric coupon analyses under static flexure loading using ANSYS APDL. Three metallic leading edge caps, Ti-6Al-4V, Inconel 718, and 15-5 PH stainless steel, were combined with IM7/8551-7 carbon fiber composites. Parametric variations included changes in metal cap material, geometric designs of the joint, and other things. Performance was evaluated in terms of failure stress, interlaminar shear strains, interface integrity, and failure margins. Results reveal that cap design and cap material critically govern structural response, with distinct interchanges between strength-to-weight efficiency, interface stresses, and interlaminar shear strain. Optimal designs reduced interlaminar shear strain levels in thin wall composite blades, while retaining adequate stiffness and strength. The results underscore the importance of interface design for effective load transfer and provide design guidelines for lightweight, damage-tolerant thin wall composite fan blade structures. Full article

Low-velocity impacts can cause barely visible impact damage (BVID) in carbon-fiber-reinforced polymer (CFRP) laminates, leading to significant reductions in residual compressive strength. Compression-after-impact (CAI) tests are therefore essential for damage-tolerance design, but existing fixtures often allow global buckling or edge crushing, which can compromise test accuracy. This study experimentally investigates the CAI response of two symmetric angle-ply CFRP laminates with reversed stacking sequences, [0/−45/45/90]s and [90/45/−45/0]s, using a modified CAI fixture. Compared to standard CAI rigs, the modified fixture combines the lateral guidance with anti-buckling plates that clamp the upper and lower specimen edges using a bolt–nut assembly, thereby reducing the active gauge length and stabilizing the panel during compression. Rectangular plate specimens were first impacted at low velocity with a hemispherical projectile; the BVID threshold was defined by a permanent indentation depth of 0.8 mm for [0/−45/45/90]s and 0.7 mm for [90/45/−45/0]s, measured 24 h after impact. Subsequent CAI tests showed about a 22% reduction in maximum compressive load at the BVID level for both layups, while the post-impact compressive stiffness decreased by 17% for [0/−45/45/90]s and 6% for [90/45/−45/0]s. These results demonstrate that reversing the symmetric layup significantly affects stiffness degradation and that the proposed CAI setup suppresses global buckling and edge-dominated failures in all testson the investigated thin CFRP laminates, enabling repeatable residual-strength and stiffness measurements. Full article

The growing consumption of natural aggregates in concrete production has raised significant environmental and sustainability concerns, motivating the search for alternative and waste-based materials. Walnut shells (WSs), an abundant agricultural by-product, have attracted increasing attention as a potential partial replacement for fine and coarse aggregates in concrete. This study presents a comprehensive review and comparative analysis of published experimental data examining the influence of WS incorporation on the fresh and hardened properties of concrete. Data from the literature covering WS replacement ratios ranging from 1% to 50% were systematically compiled and evaluated with respect to compressive strength, splitting tensile strength, flexural strength, slump, and density. The results indicate that low WS replacement levels (generally ≤10%) may preserve acceptable mechanical performance while contributing to sustainability objectives, whereas higher replacement ratios lead to pronounced reductions in strength, particularly in splitting tensile and flexural capacities. Workability consistently decreases with increasing WS content due to the porous structure and high water absorption of the shells, while density reductions suggest the potential for producing lightweight concrete. Overall, the findings demonstrate that WSs can be effectively utilized in concrete at limited replacement levels, provided that mix design parameters and performance requirements are carefully balanced. The study also highlights the need for further research focusing on durability, long-term behavior, and optimization strategies to enhance the practical applicability of WS-based sustainable concrete. Full article

Density functional theory (DFT) was used to investigate how bisubstitution doping in graphene alters its electronic structure and interfacial stability with two model lignocellulosic binders, carboxymethylcellulose (CMC), and a representative aromatic fragment (LCmA). The properties were evaluated at the ωB97X-D/LANL2DZ level for pristine graphene and its bisubstitution-doped variants with nitrogen (graphene-2N) and sulfur (graphene-2S), integrating frontier orbitals, electrostatic potential (ESP) maps, electronic localization functions (ELF/LOL), and QTAIM topology. Doping with 2N markedly reduces the HOMO–LUMO gap from 0.16052 eV (graphene) to 0.10560 eV (−34.2%), while 2S reduces it to 0.14222 eV (−11.4%), evidencing different electronic activation mechanisms. The interaction energies show doping-controlled selectivity: In pristine graphene, adsorption strongly favors LCmA ($\mathsf{\Delta }{E}_{int}$ = −99.3 kcal·mol⁻¹) over CMC (−23.7 kcal·mol⁻¹); in graphene-2N, CMC coupling intensifies (−93.7 kcal·mol⁻¹) while maintaining a high interaction with LCmA (−74.3 kcal·mol⁻¹); and in graphene-2S, CMC remains favorable (−71.9 kcal·mol⁻¹) while LCmA falls to a practically marginal regime (−4.1 kcal·mol⁻¹). QTAIM the presence of confirms closed-layer interactions in all complexes (∇²Pc > 0, H > 0, |V|/G < 1), with |V|/G close to unity for graphene–LCmA (0.994) and less compaction when doped with 2N (0.760 for 2N–LCmA). The bisubstitution modulates the electronic heterogeneity of the basal plane and redefines the binder–surface compatibility, favoring the multipoint anchoring of polar ligands in 2N and penalizing efficient aromatic stacking in 2S. Full article

This study investigated the properties of a composite NiCrFeSiB coating with fine-dispersed WC additives, deposited by the HVOF method. The NiCrFeSiB powder alloy with WC additives was applied to a steel substrate. The WC content in the coating was 10, 15, and 20% by weight. The particle size distribution of the mixture ranged from 3 to 10 µm. The WC used was the WC8 alloy (92% WC, 8% Co). The levels of stress, phase composition, hardness, wear resistance, and coating structure were investigated. The studies revealed that the structure was primarily composed of the γ-Ni-Fe solid solution phase, with secondary phases including Ni₃B, Fe₃B, (Cr,)₂B, and carbides of the W₂C, WC, M₇C₃ type. A small amount of the initial WC particles was also present. The use of a fine-dispersed NiCrFeSiB powder mixture with WC particles resulted in a nearly twofold increase in hardness and wear resistance compared to the same parameters of the coating without WC. The coating with 20% WC exhibited the highest hardness. However, its wear resistance was lower than that of the coating with 15% WC. This fact could be explained by a slight difference in the phase composition and an increase in the proportion of the unsolidified WC phase in the structure. This led to the spalling of fine particles and a reduction in wear resistance. The study demonstrated the feasibility of using a fine-dispersed NiCrFeSiB coating with WC additives without additional remelting. Similar hardness and wear resistance results were achieved immediately after HVOF spraying when using a fine-dispersed NiCrFeSiB + 15% WC/Co mixture with a 92/8 composition. This simplification of the technology reduced the coating application process time. It also lowered production costs by eliminating the remelting stage. Full article

The performance of polymer nanocomposites is governed primarily by the structure and properties of the matrix–filler interphase. This study presents a quantitative Raman spectroscopy analysis of interphase evolution in epoxy nanocomposites reinforced with two-dimensional WS₂, whose surface chemistry was systematically tuned via grafting of aminoacetic acid (AA) at concentrations of 2.5, 5.0, and 7.5 wt.%. By tracking peak shifts, linewidths, intensity ratios, and integrated areas of the characteristic WS₂ phonon modes (2LA(M) + E₂g¹, A₁g, and defect-related bands), we establish a non-linear, concentration-dependent interfacial response. Minor spectral variations at 2.5 wt.% AA indicate limited interfacial interaction. At 5.0 wt.% AA, suppression of the A₁g mode and significant band broadening reflect increased structural disorder. At 7.5 wt.% AA, coordinated red shifts (~−1.8 cm⁻¹) and the appearance of an additional band near 432.8 cm⁻¹ suggest the development of a strain-mediated interfacial state. Overall, increasing AA concentration leads to a non-linear evolution of the WS₂–epoxy interface, as reflected in peak positions, linewidths and intensity ratios. These Raman-derived descriptors correlate directly with enhanced mechanical properties (flexural and tensile strength) and thermal stability (Vicat softening point) of the composites. The results demonstrate that effective interfacial coupling requires a critical surface coverage and that Raman spectroscopy serves as a powerful tool for non-destructively probing and optimizing interphase architecture in TMD/polymer systems. Full article

The use of resource-saving technology in road construction material production is a current problem, the solution of which will allow us to increase the environmental and economic efficiency of the road construction industry. Nowadays, secondary raw materials are widely used in highway construction, obtained both from the waste of old road construction materials and collected from other industries. During asphalt production, up to 90% of raw materials can be replaced by reclaimed asphalt pavement (RAP). This technology requires residual binder modification to reduce the negative impact on the technological and operational asphalt concrete properties. On the other hand, the use of rubber crumbs or granules obtained from the disposal of old car tires in asphalt–concrete mixtures is widespread. However, some types of car tires cannot be used as raw materials to produce an effective modifier. Truck tires and tires from special vehicles are suitable for use as a modifier for asphalt–concrete mixtures. Tires designed for passenger cars do not contain enough polymer. As an experiment on asphalt–concrete mixture production using secondary resources only, a testing facility was developed. The testing facility uses hot gas obtained by burning automobile tires in a special oven as a heat source. Rubber residues from the recycling of automobile tires are used as fuel, which cannot be used to produce rubber powder or granules. RAP obtained by cold milling of the pavements of city and public roads was used as the object of the research. When studying the characteristics of the asphalt–concrete-mixture-based binder, it was found that the sulfur compounds present in the composition of hot gases change the properties of the binder, leading to a serious deterioration in the technological characteristics of asphalt–concrete mixtures. The asphalt–concrete mixture obtained during RAP processing is characterized by a narrow temperature range in which it can be laid and compacted to the required density values. After laying the pavement, quality control revealed a significant variation (the number of air voids ranged from 0.8 to 5.5%) in the average density of samples taken from the compacted layer. In addition, there were significant violations of the longitudinal evenness of the finished coating. Experiments were carried out to extract the binder from asphalt–concrete mixtures before and after regeneration. The physico-mechanical and rheological characteristics were studied and qualitative analysis of the binder was realized by IR spectroscopy. The data obtained allow us to establish the mechanism of how sulfur-containing gases influence the bitumen binder’s properties in asphalt mixtures. Additionally, the features of thermo-oxidative degradation occurring during the hot recycling of asphalt–concrete mixtures were established. A justification is also given for the need to use anti-aging modifiers to restore the properties of the residual binder. Full article

This study evaluates the mechanical performance and failure characteristics of concrete reinforced with corn fibers as a sustainable natural additive. Corn fibers were incorporated at 0.25%, 0.5%, and 1.5% by weight of cement, with a control mix used for comparison. All mixtures were prepared at a constant water–cement ratio and adjusted for workability using a high-range water-reducing admixture. Results indicate that fiber dosage significantly influences strength and fracture behavior. The 0.5% fiber content yielded the best performance, improving compressive and flexural strength by approximately 36% and 24%, respectively, and promoting enhanced crack control and ductile response. In contrast, excessive fiber addition reduced performance due to fiber clustering and higher pore content. This study confirms that properly proportioned corn fibers can enhance concrete properties while encouraging sustainable construction through the reuse of agricultural waste. SEM further indicated a denser and more refined microstructure in the fiber-modified matrix. An ANOVA analysis and Tukey’s HSD post hoc test were performed to assess the influence of corn fiber content on the compressive, flexural, and tensile strengths of concrete mixtures, revealing statistically significant effects. Overall, the results highlight the potential of corn fiber reinforcement to improve the short-term mechanical performance of concrete mixes. Full article

The widespread deployment of service robots in domestic and professional environments demands structural solutions that simultaneously achieve high stiffness, low mass, and intrinsic safety. Traditional metallic structural designs face a fundamental physical conflict: achieving high stiffness typically results in excessive mass, which compromises operational safety and battery life. To solve this, this paper presents a critical review of an integrated lightweighting strategy combining material selection, structural design, and additive manufacturing for Carbon-Fiber-Reinforced Polymer (CFRP) service robot structures. Three critical findings are presented. First, specific stiffness is established as the governing criterion for material selection, providing a unified basis to resolve the stiffness–mass conflict. Second, among current 3D printing techniques, Fused Deposition Modeling (FDM) with continuous-fiber reinforcement overcomes the geometric constraints of traditional molding, enabling the fabrication of complex, customized structures. Third, to realize the full potential of 3D-printed CFRP, we highlight the importance of integrating material properties (anisotropy), structural design (topology optimization), and manufacturing processes (path planning) into a concurrent framework. This integrated approach is validated through a collaborative robotic-arm case study, achieving a 30% reduction in structural mass. Full article