Journal of Composites Science

29 pages, 5717 KiB

Open AccessReview

Alkali-Activated Materials Reinforced via Fibrous Biochar: Modification Mechanisms, Environmental Benefits, and Challenges

by Yukai Wang, Kai Zheng, Lilin Yang, Han Li, Yang Liu, Ning Xie and Guoxiang Zhou

J. Compos. Sci. 2025, 9(6), 298; https://doi.org/10.3390/jcs9060298 - 11 Jun 2025

Abstract

Alkali-activated materials, as a low-carbon cementitious material, are widely known for their excellent durability and mechanical properties. In recent years, the modification of alkali-activated materials using biochar has gradually attracted attention. Fibrous biochar has a highly porous structure and large specific surface area, [...] Read more.

Alkali-activated materials, as a low-carbon cementitious material, are widely known for their excellent durability and mechanical properties. In recent years, the modification of alkali-activated materials using biochar has gradually attracted attention. Fibrous biochar has a highly porous structure and large specific surface area, which can effectively adsorb alkaline ions in alkali-activated materials, thereby improving their pore structure and density. Additionally, the surface of the biochar contains abundant functional groups and chemically reactive sites. These can interact with the active components in alkali-activated materials, forming stable composite phases. This interaction further enhances the material’s mechanical strength and durability. Moreover, the incorporation of biochar endows alkali-activated materials with special adsorption capabilities and environmental remediation functions. For instance, they can adsorb heavy metal ions and organic pollutants from water, offering significant environmental benefits. However, research on biochar-modified alkali-activated materials is still in the exploratory phase. There are several challenges, such as the unclear mechanisms of how biochar preparation conditions and performance parameters affect the modification outcomes, and the need for further investigation into the compatibility and long-term stability of biochar with alkali-activated materials. Future research should focus on these issues to promote the widespread application of biochar-modified alkali-activated materials. Full article

(This article belongs to the Special Issue Manufacturing of Fibrous Composites for Engineering Applications, Volume II)

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23 pages, 15965 KiB

Open AccessArticle

Parametric Optimization of Dry Sliding Wear Attributes for AlMg1SiCu Hybrid MMCs: A Comparative Study of GRA and Entropy-VIKOR Methods

by Krishna Prafulla Badi, Srinivasa Rao Putti, Maheswara Rao Chapa and Muralimohan Cheepu

J. Compos. Sci. 2025, 9(6), 297; https://doi.org/10.3390/jcs9060297 - 10 Jun 2025

Abstract

In recent days, aluminum-based hybrid composites have garnered more interest than monolithic alloys owing to their remarkable properties, encompassing a high strength-to-weight ratio, excellent corrosion resistance, and impressive wear durability. The present study attempts to optimize the multiple wear attribute characteristics of Al6061/SiC/Al [...] Read more.

In recent days, aluminum-based hybrid composites have garnered more interest than monolithic alloys owing to their remarkable properties, encompassing a high strength-to-weight ratio, excellent corrosion resistance, and impressive wear durability. The present study attempts to optimize the multiple wear attribute characteristics of Al6061/SiC/Al₂O₃ hybrid composites using grey and entropy-based VIKOR techniques. The composites were produced by adding equal proportions of SiC/Al₂O₃ (0–12 wt.%) ceramics through the stir-casting process, using an ultrasonication setup. Dry sliding wear experiments were executed with tribometer variants, namely reinforcement content (wt.%), load (N), sliding velocity (v), and sliding distance (SD), following L₂₇ OA. The optimal combination of process variables for achieving high GRG values from grey analysis was found to be A₃-B₃-C₃-D₃. The S/N ratios and ANOVA results for GRG indicated that RF content (wt.%) is the predominant component determining multiple outcomes, followed by sliding distance, load, and sliding velocity. The multi-order regression model formulated for the VIKOR index (Q_i) displayed high significance and more accuracy, with a variance of 0.0216 and a coefficient of determination (R²), and adjusted R² values of 99.60% and 99.14%. Subsequent morphological studies indicated that plowing, abrasion, and adhesion mechanisms are the dominant modes of wear. Full article

(This article belongs to the Special Issue Recent Progress in Hybrid Composites)

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24 pages, 10292 KiB

Open AccessReview

Improving Surface Roughness of FDM-Printed Parts Through CNC Machining: A Brief Review

by Mauro Carta, Gabriela Loi, Mohamad El Mehtedi, Pasquale Buonadonna and Francesco Aymerich

J. Compos. Sci. 2025, 9(6), 296; https://doi.org/10.3390/jcs9060296 - 8 Jun 2025

Viewed by 117

Abstract

Fused Deposition Modeling (FDM) has evolved from a rapid prototyping technique to an established manufacturing process for various industrial applications, including aerospace, robotics, biomedical engineering, and food production. Despite its versatility, the surface quality and dimensional accuracy of FDM-printed parts remain significant challenges, [...] Read more.

Fused Deposition Modeling (FDM) has evolved from a rapid prototyping technique to an established manufacturing process for various industrial applications, including aerospace, robotics, biomedical engineering, and food production. Despite its versatility, the surface quality and dimensional accuracy of FDM-printed parts remain significant challenges, limiting their applicability in high-performance and precision-driven industries. Some of the primary limitations of FDM are volumetric error, shape deviation, and surface roughness, which directly affect the mechanical properties and functional performance of printed components. Post-processing techniques are available to mitigate these problems. Among the available post-processing techniques, CNC machining has emerged as a viable solution for improving the surface finish and dimensional precision of FDM parts. The integration of subtractive CNC machining with additive FDM printing enables the development of hybrid manufacturing strategies, leveraging the design freedom of 3D printing while ensuring superior surface quality. This paper presents a comprehensive review of recent studies on CNC post-processing of FDM-printed parts, analyzing its impact on surface roughness, dimensional accuracy, and material properties. Additionally, key process parameters influencing the effectiveness of CNC machining are discussed. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2025)

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19 pages, 9059 KiB

Open AccessArticle

Machine Vision Framework for Real-Time Surface Yarn Alignment Defect Detection in Carbon-Fiber-Reinforced Polymer Preforms

by Lun Li, Shixuan Yao, Shenglei Xiao and Zhuoran Wang

J. Compos. Sci. 2025, 9(6), 295; https://doi.org/10.3390/jcs9060295 - 7 Jun 2025

Viewed by 276

Abstract

Carbon-fiber-reinforced polymer (CFRP) preforms are vital for high-performance composite structures, yet the real-time detection of surface yarn alignment defects is hindered by complex textures. This study introduces a novel machine vision framework to enable the precise, real-time identification of such defects in CFRP [...] Read more.

Carbon-fiber-reinforced polymer (CFRP) preforms are vital for high-performance composite structures, yet the real-time detection of surface yarn alignment defects is hindered by complex textures. This study introduces a novel machine vision framework to enable the precise, real-time identification of such defects in CFRP preforms. We proposed obtaining the frequency spectrum by removing the zero-frequency component from the projection curve of images of carbon fiber fabric, aiding in the identification of the cycle number for warp and weft yarns. A texture structure recognition method based on the artistic conception drawing (ACD) revert is applied to distinguishing the complex and diverse surface texture of the woven carbon fabric prepreg from potential surface defects. Based on the linear discriminant analysis for defect area threshold extraction, a defect boundary tracking algorithm rule was developed to achieve defect localization. Using over 1500 images captured from actual production lines to validate and compare the performance, the proposed method significantly outperforms the other inspection approaches, achieving a 97.02% recognition rate with a 0.38 s per image processing time. This research contributes new scientific insights into the correlation between yarn alignment anomalies and a machine-vision-based texture analysis in CFRP preforms, potentially advancing our fundamental understanding of the defect mechanisms in composite materials and enabling data-driven quality control in advanced manufacturing. Full article

(This article belongs to the Special Issue Carbon Fiber Composites, 4th Edition)

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17 pages, 1075 KiB

Open AccessArticle

Computational Study of Ultra-Small Gold Nanoparticles with Amphiphilic Polymer Coating

by Paulo Siani, Edoardo Donadoni, Giulia Frigerio, Marialaura D’Alessio and Cristiana Di Valentin

J. Compos. Sci. 2025, 9(6), 294; https://doi.org/10.3390/jcs9060294 - 7 Jun 2025

Viewed by 143

Abstract

Nanomedicine is rapidly evolving, with tailored nanoparticles enabling precise cellular-level interventions. Despite significant advances, challenges, such as rapid clearance and off-target effects, hinder the clinical translation of many nanosystems. Among the available nanoplatforms, gold nanoparticles (AuNPs) stand out due to their unique surface [...] Read more.

Nanomedicine is rapidly evolving, with tailored nanoparticles enabling precise cellular-level interventions. Despite significant advances, challenges, such as rapid clearance and off-target effects, hinder the clinical translation of many nanosystems. Among the available nanoplatforms, gold nanoparticles (AuNPs) stand out due to their unique surface chemistry, low toxicity, and excellent biocompatibility. In this work, we present a multi-level computational investigation of ultra-small AuNPs coated with non-conventional amphiphilic polymer chains via atomistic and coarse-grained molecular dynamics. Through high-level-resolution atomistic simulations, we investigate how variations in grafting density impact the collective behaviors of these amphiphilic polymer chains within the coating by quantifying relevant conformational, structural, and energetic descriptors, such as the radius of gyration, terminal group presentation, polymer coating thickness, brush height, and solvation energy. Our results reveal a conformational shift of polymer chains from coiled to stretched as grafting density increases, with a direct effect on the polymer conformational regime, terminal group presentation, and coating thickness. In parallel, we further benchmark low-level coarse-grained models using the atomistic data as a reference, demonstrating their ability to correctly reproduce the atomistic trends. This computational investigation reveals how key descriptors vary with grafting density and provides the tools for conducting similar studies on broader time and length scales, thereby advancing the rational design of nanosystems for nanomedicine. Full article

(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)

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23 pages, 11273 KiB

Open AccessArticle

The In-Plane Compression Response of Thermoplastic Composites: Effects of High Strain Rate and Type of Thermoplastic Matrix

by Svetlana Risteska, Marco Peroni, Sara Srebrenkoska, Vineta Srebrenkoska, Tatjana Glaskova-Kuzmina and Andreas Hornig

J. Compos. Sci. 2025, 9(6), 293; https://doi.org/10.3390/jcs9060293 - 7 Jun 2025

Viewed by 101

Abstract

Designing thermoplastic composites for particular uses requires understanding their dynamic mechanical behaviour, which affects how well they operate in practical settings. The Split Hopkinson pressure bar (SHPB) test allows for evaluating these materials’ responses to high strain rates. In this study, an in-situ [...] Read more.

Designing thermoplastic composites for particular uses requires understanding their dynamic mechanical behaviour, which affects how well they operate in practical settings. The Split Hopkinson pressure bar (SHPB) test allows for evaluating these materials’ responses to high strain rates. In this study, an in-situ laser-assisted fibre placement (LAFP) machine has been utilised to produce laminate composites with varied designs, i.e., different angles of layers [0/45/–45/90]_4s, using three types of thermoplastic tapes (UD-CF/PPS, UD-CF/PEEK, and UD-CF/PEKK). Using a servo-hydraulic testing machine and SHPB apparatus, we have examined the dynamic compressive behaviour of thermoplastic laminate composites with various matrices (PPS, PEEK, and PEKK) in in-plane directions and at strain rates of approx. 0.001, 0.1, 10, 800, 1800/s. Experimental results indicate that the type of thermoplastic matrix and strain rate significantly affect how the laminate composites behave. The in-plane compressive strength and modulus increase approximately linearly with the strain rate. According to the fracture of morphological pictures, the main failure mechanism of all three types of specimens is shear failure under in-plane compression loads, which is followed by delamination and burst. Full article

(This article belongs to the Special Issue Additive Manufacturing of Advanced Composites, 2nd Edition)

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27 pages, 4956 KiB

Open AccessReview

Recent Advancements in Polypropylene Fibre-Reinforced 3D-Printed Concrete: Insights into Mix Ratios, Testing Procedures, and Material Behaviour

by Ben Hopkins, Wen Si, Mehran Khan and Ciaran McNally

J. Compos. Sci. 2025, 9(6), 292; https://doi.org/10.3390/jcs9060292 - 6 Jun 2025

Viewed by 249

Abstract

This review presents a comprehensive analysis of polypropylene (PP) fibre incorporation in three-dimensional printed concrete (3DPC), focusing on the material behaviour in both fresh and hardened states. PP fibres play a critical role in improving rheological properties such as buildability, flowability, and extrudability. [...] Read more.

This review presents a comprehensive analysis of polypropylene (PP) fibre incorporation in three-dimensional printed concrete (3DPC), focusing on the material behaviour in both fresh and hardened states. PP fibres play a critical role in improving rheological properties such as buildability, flowability, and extrudability. While increased fibre content enhances interlayer bonding and shape retention through the fibre bridging mechanism, it also raises yield stress and viscosity, which may compromise extrudability. In the hardened state, PP fibres contribute to improvements in compressive and flexural strength up to an optimal dosage, beyond which performance may decline due to fibre clustering and reduced packing density. When aligned with the printing direction, fibres are particularly effective in mitigating shrinkage-induced cracking by redistributing internal tensile stress. However, their inclusion can lead to a slight increase in porosity and promote mechanical anisotropy. This review also discusses mix design parameters, fibre characteristics, and experimental protocols, while identifying key research gaps including the lack of standardized testing methods, limited understanding of fibre orientation effects, and insufficient exploration of hybrid fibre systems. Based on the synthesis of reported studies, optimal print quality and structural consistency have been associated with the use of 6 mm long fibres, nozzle diameters of 4 to 6 mm, and printing speeds ranging from 40 to 60 mm/s. Overall, PP fibre reinforcement shows strong potential for enhancing the structural integrity and dimensional stability of 3D-printed concrete, while emphasizing the need for further studies to optimize its use in practice. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2025)

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14 pages, 6282 KiB

Open AccessArticle

Influence of Jointing Methods on the Mechanical Properties of CFRTP Structure Under Bending Load

by Yi Wan, Linshu Meng, Hirokuni Wataki and Jun Takahashi

J. Compos. Sci. 2025, 9(6), 291; https://doi.org/10.3390/jcs9060291 - 6 Jun 2025

Viewed by 217

Abstract

Jointing is inevitable for CFRTP (carbon fiber reinforced thermoplastic) component applications in the automotive industry. In this study, commonly used jointing methods were applied to fasten CFRTP components. Three types of jointing methods. Ultrasonic welding, bolted joints, and adhesive joining, and three types [...] Read more.

Jointing is inevitable for CFRTP (carbon fiber reinforced thermoplastic) component applications in the automotive industry. In this study, commonly used jointing methods were applied to fasten CFRTP components. Three types of jointing methods. Ultrasonic welding, bolted joints, and adhesive joining, and three types of CFRTP materials, conventional cross-ply, ultra-thin prepreg cross-ply, and sheet molding compounds, were selected. The influence of the jointing methods on mechanical properties and damage patterns under bending load has been investigated. The finite element models were developed to predict the hazardous area and structural stiffness of jointed structures; the simulation results showed good agreement with experimental ones. The results indicate that the ultrasonic welding could reach similar bending stiffness compared to adhesive joining, whereas the stiffness of bolt jointed structures is relatively lower due to the contact separation induced by the bending deformation. Overall, the finite element model results correlated well with the experimental data. Full article

(This article belongs to the Special Issue Mechanical Properties of Composite Materials and Joints)

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30 pages, 6120 KiB

Open AccessReview

Review of Experimental Testing and Fire Performance of Mass Timber Structures

by Sumita Maharjan, Tharaka Gunawardena and Priyan Mendis

J. Compos. Sci. 2025, 9(6), 290; https://doi.org/10.3390/jcs9060290 - 5 Jun 2025

Viewed by 148

Abstract

Mass timber construction is gaining popularity in mid-rise and tall buildings due to its sustainability, aesthetics, versatile prefabrication, light weight, and faster construction time compared to conventional building materials such as concrete and steel. One of the challenges with timber construction is a [...] Read more.

Mass timber construction is gaining popularity in mid-rise and tall buildings due to its sustainability, aesthetics, versatile prefabrication, light weight, and faster construction time compared to conventional building materials such as concrete and steel. One of the challenges with timber construction is a potential fire hazard, and the risk is even aggravated in taller buildings due to the increased evacuation period. Several researchers have identified and reported important parameters that will have direct influence over mass timber fire performance behaviour. However, the current findings from the literature do not provide a correlation between the key parameters and the fire performance behaviour. This paper presents a review of experimental fire testing of mass timber structures and analyses the fire performance results output obtained from the experimental testing. This paper attempts to identify several key parameters that influence the fire performance behaviour of mass timber structures, such as peak temperature, charring rate and decay behaviour. The correlation between the key parameters and the fire performance behaviour of mass timber structures will enhance in developing a rational model to determine the time to reach the fire growth, peak temperature, charring behaviour, structural integrity (strength and stiffness reduction) and decay behaviour of the exposed timber. Full article

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21 pages, 3347 KiB

Open AccessArticle

Sustainable Building Materials: Optimization and Performance Analysis of Plaster/Wood Shavings Composites for Thermal Insulation

by Rachidi Mohammed Badr, Ennawaoui Amine, Bouyahia Fatima, Remaidi Mohammed, Derraz Meryiem, Mastouri Hicham, El Khoudri Mouad, Chhiti Younes and Ennawaoui Chouaib

J. Compos. Sci. 2025, 9(6), 289; https://doi.org/10.3390/jcs9060289 - 5 Jun 2025

Viewed by 189

Abstract

The development of sustainable insulation materials plays a crucial role in creating energy-efficient and environmentally responsible buildings. This study investigates eco-friendly composite materials based on plaster and wood shavings for insulation purposes. Incorporating wood shavings into plaster improves thermal insulation and mechanical behavior [...] Read more.

The development of sustainable insulation materials plays a crucial role in creating energy-efficient and environmentally responsible buildings. This study investigates eco-friendly composite materials based on plaster and wood shavings for insulation purposes. Incorporating wood shavings into plaster improves thermal insulation and mechanical behavior by enhancing porosity, reducing density, and improving bonding. As the wood shaving content increases from 5% to 15%, the thermal conductivity decreases from 0.252 W/mK to 0.099 W/mK, reflecting superior insulating performance. Concurrently, thermal resistance rises, showcasing enhanced insulation. The material also demonstrates increased flexibility, with the Young’s modulus decreasing at higher wood shaving proportions. Numerical simulations confirm these observations, indicating a 12 K temperature drop for composites with 15% wood shavings compared to a 6 K drop for pure plaster. This study suggests that an insulation thickness of 6–7 cm for the 15% composite strikes the optimal balance between performance and cost-efficiency. The findings underscore the potential of wood shavings to significantly enhance the thermal efficiency and mechanical adaptability of plaster composites, promoting sustainable and effective building insulation solutions. Full article

(This article belongs to the Special Issue Novel Cement and Concrete Materials)

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28 pages, 5048 KiB

Open AccessArticle

Voxel-Based Finite Element Investigation of Micromechanics Models for Stiffness Prediction of Cross-Ply Laminates

by Darya Forooghi and Yunhua Luo

J. Compos. Sci. 2025, 9(6), 288; https://doi.org/10.3390/jcs9060288 - 4 Jun 2025

Viewed by 176

Abstract

Laminate plate and shell structures with symmetric cross-ply configurations are widely used due to their high stiffness-to-weight ratio. However, conventional lamination theories rely on simplifying assumptions that may introduce inaccuracies. This study evaluates the predictive capability of such theories by integrating multiple micromechanics [...] Read more.

Laminate plate and shell structures with symmetric cross-ply configurations are widely used due to their high stiffness-to-weight ratio. However, conventional lamination theories rely on simplifying assumptions that may introduce inaccuracies. This study evaluates the predictive capability of such theories by integrating multiple micromechanics models with First-Order Shear Deformation Theory (FSDT), and comparing the results against voxel-based finite element modeling (VB-FEM), which serves as a high-fidelity numerical reference. A range of models—including Voigt–Reuss, Chamis, Halpin–Tsai, Bridging, and two iterative isotropized formulations—are assessed for unidirectional laminae with fiber volume fractions from 40% to 73%. Quantitative comparison reveals that while all models predict the longitudinal modulus accurately, significant deviations arise in predicting transverse and shear properties. The Bridging Model consistently yields the closest agreement with VB-FEM across all five elastic constants, maintaining accuracy even at high volume fractions where the modified Halpin–Tsai model begins to fail. Discrepancies in micromechanics-based lamina properties propagate to laminate-level stiffness predictions, highlighting the critical role of model selection. These findings establish VB-FEM as a valuable tool for validating analytical models and guide improved modeling strategies for laminated composite design. Full article

(This article belongs to the Special Issue Characterization and Modeling of Composites, 4th Edition)

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18 pages, 9085 KiB

Open AccessArticle

Optimizing the Tribological Performance of Copper-Reinforced A356 Aluminum Alloy: Influence of Heat Treatment and Composition Variation

by G. Divya Deepak, Nithesh Kashimat, Karthik Birur Manjunathaiah, Vignesha Nayak, Gajanan Anne and Sathyashankara Sharma

J. Compos. Sci. 2025, 9(6), 287; https://doi.org/10.3390/jcs9060287 - 4 Jun 2025

Viewed by 311

Abstract

Recent progress in metal matrix composites (MMCs) has led to significant research efforts aimed at refining reinforcement methods and processing techniques and enhancing material properties. Incorporating reinforcements has notably improved both mechanical strength and tribological performance while addressing issues such as porosity and [...] Read more.

Recent progress in metal matrix composites (MMCs) has led to significant research efforts aimed at refining reinforcement methods and processing techniques and enhancing material properties. Incorporating reinforcements has notably improved both mechanical strength and tribological performance while addressing issues such as porosity and particle agglomeration. This study investigates the impact of copper reinforcement (1–4 wt.%) on the tribological characteristics of A356 alloy under both as-cast and heat-treated conditions. The process of heat treatment involved age hardening, where the composites were solution heat treated (SHT) at 535 °C for 2 h, followed by rapid quenching and aging at 100 °C and 200 °C. The results demonstrate that increasing the copper content enhances the composite’s mechanical properties. Specifically, heat treatment promoted the redistribution of the Al₂Cu intermetallic phase during peak aging, leading to improved hardness and wear resistance. Wear testing demonstrated that heat-treated composites exhibited significantly better wear resistance than their as-cast counterparts, with improvements of 50–60% under lower loads and 80–90% under higher loads. Among the tested samples, A356 alloy reinforced with 4 wt.% copper showed the lowest wear rate across all the applied loads, along with a reduced coefficient of friction and enhanced load-bearing capacity, minimizing material deformation. Additionally, aging at 100 °C resulted in the greatest hardness and the lowest wear rate in comparison to untreated A356 alloy. These findings underscore the viability of copper-reinforced A356 composites for applications demanding enhanced mechanical characteristics and wear resistance. Full article

(This article belongs to the Special Issue Mechanical Properties of Composite Materials and Joints)

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18 pages, 5174 KiB

Open AccessArticle

A Numerical Study of the Effect of Hole Offset on Stress Concentrations Due to a Square Hole in a Quasi-Isotropic Composite Laminate

by Matthew K. Pirkle and Pankaj K. Mallick

J. Compos. Sci. 2025, 9(6), 286; https://doi.org/10.3390/jcs9060286 - 3 Jun 2025

Viewed by 271

Abstract

The purpose of this study was to investigate the effect of hole offset of a square hole with rounded corners on stress concentration in a finite-width [0₃/(±45)₃/90₃]_S quasi-isotropic composite laminate using finite element analysis (FEA). The [...] Read more.

The purpose of this study was to investigate the effect of hole offset of a square hole with rounded corners on stress concentration in a finite-width [0₃/(±45)₃/90₃]_S quasi-isotropic composite laminate using finite element analysis (FEA). The corner radius of the square hole and its offset location were varied. For comparison, a circular hole, with its diameter equal to the sides of the square hole, was also considered. It is observed that the maximum stress concentration factor occurs in the 0° laminas, and it increases with decreasing hole edge-to-laminate edge distance. For the offset holes, both lamina and laminate stress concentration factors increase with decreasing hole edge-to-laminate edge distance, i.e., with increasing offset. The laminate stress concentration factor for the square holes decreases with increasing corner radius, and after reaching a minimum value, it starts to increase and approaches that of a circular hole. A square hole has a lower stress concentration at its corners than do the edges of a circular hole, if the corner radius is higher than a minimum value, which is dependent on the offset distance. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Mechanical Analysis of Composite Materials)

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20 pages, 7135 KiB

Open AccessArticle

Effects of Nanofiber Interleaving on the Strength and Failure Behavior of Co-Cured Composite Joints with Fiber Orientation Mismatch

by Abdul Bari Abdul Raheman, Kaan Bilge and Melih Papila

J. Compos. Sci. 2025, 9(6), 285; https://doi.org/10.3390/jcs9060285 - 2 Jun 2025

Viewed by 330

Abstract

This study investigates the effect of nanofiber interleaving on the mechanical performance of co-cured composite lap joints with effective fiber orientation mismatch at the joint interface. Joint configurations were defined by dominant yarn orientations at the bond line—denoted as (lower-substrate|upper-substrate)—and tested in (0|0), [...] Read more.

This study investigates the effect of nanofiber interleaving on the mechanical performance of co-cured composite lap joints with effective fiber orientation mismatch at the joint interface. Joint configurations were defined by dominant yarn orientations at the bond line—denoted as (lower-substrate|upper-substrate)—and tested in (0|0), (90|90), and mismatched (0|90) setups using an 8-harness satin (8HS) fabric architecture, with and without nanofiber interlayers. Mechanical testing revealed an over ~25% reduction in lap shear strength for the (0|90) configuration relative to the matched (0|0) and (90|90) joints. Nanofiber interleaving effectively restored this loss, achieving strength levels comparable to the matched cases. Statistical analysis using two-way ANOVA and ANOM confirmed that both fiber orientation and nanofiber interleaving significantly influence joint strength, with a notable interaction effect (p < 0.001). Fractographic analysis further showed that nanofibers enhanced delamination resistance by stabilizing crack paths and suppressing crack jumps at crimping sites, especially in (0|90) joints where 0/90 yarn intersections are prone to early failure. These findings underscore the role of nanofiber interleaving in mitigating mismatch-induced failure mechanisms and improving the structural integrity of composite bonded interfaces. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2025)

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16 pages, 19335 KiB

Open AccessArticle

The Silylation Effect of C/SiC Nanofillers on Mechanical Properties of Cellulose Nanocomposite: Insights from Molecular Dynamics Simulations

by Ahmad Y. Al-Maharma, Bernd Markert and Franz Bamer

J. Compos. Sci. 2025, 9(6), 284; https://doi.org/10.3390/jcs9060284 - 31 May 2025

Viewed by 279

Abstract

Silylation treatment improves the hydrophobicity of cellulose by reducing the number of hydroxyl groups in the cellulose chains that are available to react with moisture in the surrounding environment. Additionally, silylation increases stress transfer from cellulose to synthetic nanofillers by forming covalent bonds [...] Read more.

Silylation treatment improves the hydrophobicity of cellulose by reducing the number of hydroxyl groups in the cellulose chains that are available to react with moisture in the surrounding environment. Additionally, silylation increases stress transfer from cellulose to synthetic nanofillers by forming covalent bonds between the hydroxyl groups of cellulose and the oxidized surface of these nanofillers. This study investigates the impact of silane coupling agents on the tensile properties of cellulose nanocomposites. The cellulose nanocomposites are reinforced with four types of C/SiC-based nanofillers: carbon nanotubes, graphene nanoplatelets, silicon carbide nanotubes, and silicon carbide nanoplatelets. Subsequently, the nanofillers are subjected to surface treatment using the silane coupling agent KH550. The mechanical properties of the cellulose nanocomposites are evaluated by molecular dynamics simulations based on the polymer’s consistent forcefield. The results indicate that the reinforcements of silylated silicon carbide nanotubes and carbon nanotubes increase the tensile modulus of cellulose by 18.03% and 24.58%, respectively, compared to their untreated counterparts. Furthermore, the application of silylation treatment on the surface of C/SiC nanofillers increases the yield strength and ultimate tensile strength of cellulose nanocomposites due to enhanced load transfer between cellulose and these reinforcements. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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18 pages, 8149 KiB

Open AccessArticle

Design and Analysis of Natural Fiber-Reinforced Jute Woven Composite RVEs Using Numerical and Statistical Methods

by Jakiya Sultana and Gyula Varga

J. Compos. Sci. 2025, 9(6), 283; https://doi.org/10.3390/jcs9060283 - 31 May 2025

Viewed by 239

Abstract

Woven composites and natural fiber-reinforced composites both have widespread applications in various industries due to their appealing load-carrying capacity and performance compared to conventionally manufactured composites, such as polymeric composites. Representative volume element (RVE) generation is one of the most effective and widely [...] Read more.

Woven composites and natural fiber-reinforced composites both have widespread applications in various industries due to their appealing load-carrying capacity and performance compared to conventionally manufactured composites, such as polymeric composites. Representative volume element (RVE) generation is one of the most effective and widely adopted methods for estimating mechanical performance in current research. This study aims to explore the effects of three significant factors in woven composite RVEs: yarn spacing (from 0.5 mm to 1.5 mm), fabric thickness (from 0.2 to 0.5 mm), and shear angle (from 3.5 to 15 degrees) through finite element methods and statistical analysis to understand their effectiveness in the elastic moduli’s. The validation of this research has been conducted using available literature. The generation of representative volume elements (RVEs) and the calculation of elastic moduli were performed using ANSYS-19, including the material designer feature. The experimental design was carried out using Design-Expert software version 13, which used response surface methodology. The materials selected for this study were jute fiber and epoxy. After obtaining the elastic moduli from the ANSYS material designer, three responses were considered: longitudinal Young’s modulus (E₁₁), in-plane shear modulus (G₁₂), and major Poisson’s ratio (V₁₂). ANOVA (Analysis of Variance) and 3D contour graphs were generated to further analyze and correlate the effects of the selected materials on these responses. These investigations revealed that in comparison to twill structure, plain structure in natural fiber-reinforced woven composites could be a good alternative. Additionally, the findings highlighted that yarn spacing and fabric thickness significantly influence the considered moduli in plain-weave NFRC material RVEs. However, in twill-woven composite RVEs, the effects of yarn spacing, fabric thickness, and shear angle were found to be considerable. Moreover, statistical analysis has found the best combinations for both plain and twill structures, while the yarn spacing was 1 mm, the shear angle was 9.25 degrees, and the fabric thickness was 0.35 mm. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Modeling and Simulation of Composite Materials)

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14 pages, 1360 KiB

Open AccessArticle

Fracture Mechanics-Based Modelling of Post-Installed Adhesive FRP Composite Anchors in Structural Concrete Applications

by Amir Mofidi and Mona Rajabifard

J. Compos. Sci. 2025, 9(6), 282; https://doi.org/10.3390/jcs9060282 - 31 May 2025

Viewed by 263

Abstract

Adhesively bonded fibre-reinforced polymer (FRP) anchors have emerged as a progressive alternative to traditional steel anchors in concrete structures, owing to their superior corrosion resistance, high tensile strength, and light weight. Despite their increasing use, a robust mechanics-based bond model capable of accurately [...] Read more.

Adhesively bonded fibre-reinforced polymer (FRP) anchors have emerged as a progressive alternative to traditional steel anchors in concrete structures, owing to their superior corrosion resistance, high tensile strength, and light weight. Despite their increasing use, a robust mechanics-based bond model capable of accurately predicting the load transfer behaviour has not yet been developed. This study presents a fracture mechanics-based analytical bond model for post-installed adhesive FRP anchors embedded in concrete. The model formulation is derived from fundamental equilibrium and compatibility principles, incorporating a bilinear bond–slip law that captures both elastic and softening behaviours. A new expression for the effective bond length is also proposed. Validation of the model against a comprehensive database of direct pull-out tests reported in the literature shows excellent agreement between predicted and experimental pull-out forces (R² = 0.980; CoV = 0.058). Future research should aim to extend the proposed model to account for confinement effects, long-term durability, the impact of adhesive type, and cyclic loading conditions. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Modeling and Simulation of Composite Materials)

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18 pages, 2682 KiB

Open AccessArticle

The Ultimate Flexural Strength of Fiber-Reinforced Ceramic Matrix Composite: A Multiscale Approach

by Jacques Lamon

J. Compos. Sci. 2025, 9(6), 281; https://doi.org/10.3390/jcs9060281 - 30 May 2025

Viewed by 266

Abstract

This paper tackles the important issue of the flexural strength of continuous fiber-reinforced ceramic composite. Estimates of the flexural strength of 2D woven SiC/SiC composite are extracted from symmetric and asymmetric 3-point bending test results using three independent approaches: (1) the equations of [...] Read more.

This paper tackles the important issue of the flexural strength of continuous fiber-reinforced ceramic composite. Estimates of the flexural strength of 2D woven SiC/SiC composite are extracted from symmetric and asymmetric 3-point bending test results using three independent approaches: (1) the equations of elastic beam theory for homogeneous solids, (2) finite element analysis of the stress state, (3) stress–strain relations in the tensile outer surface of specimens. Furthermore, the flexural strength is predicted from the ultimate tensile strength using a bundle failure model based on the fracture of the critical filament. It is shown that the equation of elastic beam theory significantly overestimates the flexural strength of the 2D SiC/SiC (620 MPa), while the alternate approaches and the predictions from the ultimate tensile strength converged to ≈340 MPa. The variability of strength data was approached using the construction of p-quantile diagrams that provide an unbiased assessment of the normal distribution function. Pertinent Weibull parameters are derived using the first moment equations. Important trends in the effects of the size, stress gradient, tension–flexure relations, strength of critical filament in a tow, and populations of critical flaws are established and discussed. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Mechanical Analysis of Composite Materials)

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16 pages, 5084 KiB

Open AccessArticle

Novel Ductile Moment-Resisting Frame Compound of Steel Gusset Plate for Beam-to-Column Connections and I-Shaped FRP Profile Sections

by Ali Ghamari, Chanachai Thongchom, Adamantis G. Zapris and Violetta K. Kytinou

J. Compos. Sci. 2025, 9(6), 280; https://doi.org/10.3390/jcs9060280 - 30 May 2025

Viewed by 259

Abstract

Moment-resisting frames (MRFs) are characterized by high energy dissipation capacity relying on plastic hinge formation at the two ends of beams. Despite their numerous advantages, Fiber-Reinforced Polymer (FRP) profile sections used in MRF systems suffer from low ductility, which remains a dilemma. FRP [...] Read more.

Moment-resisting frames (MRFs) are characterized by high energy dissipation capacity relying on plastic hinge formation at the two ends of beams. Despite their numerous advantages, Fiber-Reinforced Polymer (FRP) profile sections used in MRF systems suffer from low ductility, which remains a dilemma. FRP profiles have emerged as a novel and valuable material with significant advancement in structural engineering. In this paper, an MRF system composed of novel gusset plate steel connections (to provide ductility) and FRP profile sections for beams and columns is proposed and investigated numerically and parametrically. The results indicate that up to a rotation of 0.04 rad, the proposed gusset plate dissipates energy, whereas the beam and columns remain essentially elastic. Accordingly, with an increase in the ratio of vertical length to thickness of the gusset plate, energy dissipation is reduced. Through an increase in the ratio of horizontal length to thickness of the gusset plate from 63.5 to 127 and 254, the ultimate strength of the connection is reduced by 4% to 10% and 3% to 7%, respectively. It is suggested that gusset plate thickness be selected in such a way that its slenderness is not less than 47. Subsequently, the required equation is proposed to achieve the optimum performance of the system. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Mechanical Analysis of Composite Materials)

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20 pages, 1913 KiB

Open AccessArticle

Assessment of Sustainable Structural Concrete Made by Composite Waste for the Concrete Industry: An Experimental Study

by Jamal K. Nejem, Mohammad Nadeem Akhtar, Amin H. Almasri and Mohd Salman Rais

J. Compos. Sci. 2025, 9(6), 279; https://doi.org/10.3390/jcs9060279 - 30 May 2025

Viewed by 269

Abstract

Natural sand and high OPC utilization in the concrete industry have affected our environment and caused climate change. This study developed a novel methodology to prepare modified sand by adding (50% R-Sand + 50% M-Sand) to replace 100% natural sand. The two SCMs [...] Read more.

Natural sand and high OPC utilization in the concrete industry have affected our environment and caused climate change. This study developed a novel methodology to prepare modified sand by adding (50% R-Sand + 50% M-Sand) to replace 100% natural sand. The two SCMs (5–20% of FA) and 10% of optimized SF were added to the four newly developed concrete mixes. The developed sustainable design mix concrete achieved the design and target strength after a curing period of 28 days. The findings for flexural strength showed comparable trends. Significant strength improvement was also seen at later curing ages, till 182 days. The water absorption and sulfuric acid attacks of the design mix concrete at the hardened stage were also measured. The analysis reveals that water absorption percentages tend to decline as the curing age progresses. The developed mixes show better resistance against sulfuric acid attacks than the reference mix NAC*. A mass loss of around 5% was discovered, much closer to the published studies. The developed mix 15FASFRSC showed consistent results when the modified sand (50% R-Sand + 50% M-Sand) was combined with the SCMs of (15% FA + 10% SF). Hence, the mix 15FASFRSC is the best sustainable mix for the concrete industry. Full article

(This article belongs to the Special Issue Composites: A Sustainable Material Solution, 2nd Edition)

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16 pages, 3019 KiB

Open AccessArticle

Predicting the Elastic Moduli of Unidirectional Composite Materials Using Deep Feed Forward Neural Network

by Saiaf Bin Rayhan, Md Mazedur Rahman, Jakiya Sultana and Gyula Varga

J. Compos. Sci. 2025, 9(6), 278; https://doi.org/10.3390/jcs9060278 - 30 May 2025

Viewed by 360

Abstract

Elastic moduli are important mechanical properties that describe a material’s stiffness and its deformation under elastic loading. In addition to experimental techniques, computational homogenization is commonly used for composite materials to calculate their elastic moduli. This research employs a deep learning algorithm, specifically [...] Read more.

Elastic moduli are important mechanical properties that describe a material’s stiffness and its deformation under elastic loading. In addition to experimental techniques, computational homogenization is commonly used for composite materials to calculate their elastic moduli. This research employs a deep learning algorithm, specifically a Feedforward Neural Network (FNN), to predict the longitudinal and transverse Young’s modulus, shear modulus, and Poisson’s ratio of various unidirectional (UD) composites. The predictions are based on several features, including the names of the composites, Young’s moduli and Poisson’s ratios of the fibers and matrices, and the fiber volume fraction. Initially, 20 different UD composites were selected from the existing literature. ANSYS-19 Material Designer was then utilized to calculate the elastic moduli of these materials while varying the fiber volume fraction from 0.2 to 0.7. This process generated a dataset of 1948 samples, with 80% of the data allocated for training the FNN model and the remaining 20% used to evaluate performance metrics of the test data. These metrics include mean squared error (MSE), root mean squared error (RMSE), mean absolute error (MAE), and R² score. The results indicate that, with optimized hyperparameters, the FNN model can accurately predict the elastic moduli, demonstrating its effectiveness as a tool for calculating the elastic properties of UD composites. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Modeling and Simulation of Composite Materials)

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52 pages, 4685 KiB

Open AccessReview

Epoxy Resins and Their Hardeners Based on Phosphorus–Nitrogen Compounds

by Pavel Yudaev, Bakary Tamboura, Anastasia Konstantinova, Heeralal Vignesh Babu and Krishnamurthi Muralidharan

J. Compos. Sci. 2025, 9(6), 277; https://doi.org/10.3390/jcs9060277 - 29 May 2025

Viewed by 408

Abstract

This review examines the fire-retardant properties of compositions that incorporate various classes of phosphorus–nitrogen compounds. Specifically, it focuses on nitrogen-containing derivatives of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phosphinates, phosphorus–nitrogen salts, and aryloxycyclophosphazenes. The findings indicate that these classes of fire retardants enhance the limiting oxygen index, decrease [...] Read more.

This review examines the fire-retardant properties of compositions that incorporate various classes of phosphorus–nitrogen compounds. Specifically, it focuses on nitrogen-containing derivatives of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phosphinates, phosphorus–nitrogen salts, and aryloxycyclophosphazenes. The findings indicate that these classes of fire retardants enhance the limiting oxygen index, decrease heat and smoke emission indices in epoxy compositions, and facilitate the creation of self-extinguishing materials. Notably, aryloxycyclophosphazenes with reactive functional groups emerge as the most effective fire retardants, particularly in terms of their impact on the mechanical properties of epoxy compositions and compatibility with epoxy resin. This review would be a valuable resource for engineers, chemical engineers, materials scientists, and researchers engaged in the development of non-combustible polymer composites and organoelement compounds. Full article

(This article belongs to the Special Issue Polymer Composites and Fibers, 3rd Edition)

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10 pages, 1519 KiB

Open AccessArticle

Investigation of Particleboard Production from Durian Husk and Bamboo Waste

by Thi Kim Hong Tang and Nhat Quang Nguyen

J. Compos. Sci. 2025, 9(6), 276; https://doi.org/10.3390/jcs9060276 - 29 May 2025

Viewed by 332

Abstract

Agricultural residues offer promising opportunities for the development of biocomposites. Durian husk, a lignocellulosic by-product abundantly available in Southeast Asia, and bamboo waste, an underutilized biomass resource, present considerable potential for sustainable particleboard production. This study focuses on developing single-layer bio-based particleboards using [...] Read more.

Agricultural residues offer promising opportunities for the development of biocomposites. Durian husk, a lignocellulosic by-product abundantly available in Southeast Asia, and bamboo waste, an underutilized biomass resource, present considerable potential for sustainable particleboard production. This study focuses on developing single-layer bio-based particleboards using varying proportions of durian husk and bamboo waste bonded with urea formaldehyde resin. The fabricated boards were evaluated for thickness swelling, modulus of rupture, and internal bond strength according to relevant European standards. Results indicated that all particleboards met the Type P1 requirements for general-purpose use under dry conditions, as specified in BS EN 312:2010. The findings demonstrate the feasibility of converting agricultural waste into value-added, eco-friendly materials, supporting waste valorization, promoting circular economy practices, and contributing to the development of bio-based materials. Full article

(This article belongs to the Special Issue Sustainable Biocomposites, 3rd Edition)

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16 pages, 3942 KiB

Open AccessArticle

Utilization of Coal Ash for Production of Refractory Bricks

by Saniya Kaskataevna Arinova, Svetlana Sergeevna Kvon, Vitaly Yurevich Kulikov, Aristotel Zeynullinovich Issagulov and Asem Erikovna Altynova

J. Compos. Sci. 2025, 9(6), 275; https://doi.org/10.3390/jcs9060275 - 29 May 2025

Viewed by 219

Abstract

Coal combustion generates significant volumes of ash, a technogenic by-product that poses a serious threat to regional environmental sustainability (environmental chemical contamination and air pollution). This study aims to assess the feasibility of utilizing this type of ash as a raw material component [...] Read more.

Coal combustion generates significant volumes of ash, a technogenic by-product that poses a serious threat to regional environmental sustainability (environmental chemical contamination and air pollution). This study aims to assess the feasibility of utilizing this type of ash as a raw material component in the fabrication of refractory bricks and to investigate the fundamental properties of the resulting experimental products. Ash was incorporated into the batch composition at concentrations ranging from 10% to 40% by weight, blended with clay and water, then shaped through pressing and subjected to firing at 1000 °C and 1100 °C in an air atmosphere for 2 h. After complete cooling, the samples were subjected to compressive strength testing. Samples containing 40 wt% coal ash exhibited insufficient compressive strength and were therefore excluded from subsequent investigations. For the remaining samples, apparent density, open porosity and slag resistance were determined. The microstructural characterization was performed, and the phase composition of the samples was analyzed. The results revealed that the phase composition of the experimental samples differs significantly from that of the reference sample (ShA-grade chamotte brick in accordance with GOST 390-96, currently used as lining in metallurgical furnaces across the country), exhibiting a higher mullite content and the absence of muscovite. A small amount of kaolinite was detected in the experimental samples even after a 2-h firing process. This observation may be attributed to the effect of kaolinite crystallinity on the transformation process from kaolinite to metakaolinite. The mechanical strength of the experimental samples meets the relevant standards, while slag resistance demonstrated an improvement of approximately 15%. Open porosity was found to decrease in the experimental samples. In addition, a change in the pore size distribution was observed. Notably, the proportion of pores larger than 10,000 nm was significantly reduced. These findings confirm the feasibility of incorporating coal ash as a viable raw material component in the formulation of refractory materials. Full article

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18 pages, 5335 KiB

Open AccessArticle

Surface Modification of Wood Fibers with Citric Acid as a Sustainable Approach to Developing Novel Polycaprolactone-Based Composites for Packaging Applications

by Laura Simonini and Andrea Dorigato

J. Compos. Sci. 2025, 9(6), 274; https://doi.org/10.3390/jcs9060274 - 29 May 2025

Viewed by 265

Abstract

In this study, novel biodegradable polycaprolactone (PCL)-based composites for sustainable packaging applications were developed by adding surface-treated wood fibers (WFs). Specifically, the WFs were treated with citric acid (CA) to improve the fiber/matrix adhesion and then melt compounded with a PCL matrix. The [...] Read more.

In this study, novel biodegradable polycaprolactone (PCL)-based composites for sustainable packaging applications were developed by adding surface-treated wood fibers (WFs). Specifically, the WFs were treated with citric acid (CA) to improve the fiber/matrix adhesion and then melt compounded with a PCL matrix. The presence of an absorption peak at 1720 cm⁻¹ in the Fourier transform infrared (FTIR) spectra of CA-treated WFs, coupled with the increase in the storage modulus and complex viscosity in the rheological analysis, confirmed the occurrence of an esterification reaction between CA and WFs, with a consequent increase in interfacial interactions with the PCL matrix. Scanning electron microscopy (SEM) of the cryo-fractured surface of the composites highlighted that PCL was able to efficiently wet the fibers after the CA treatment, with limited fiber pull-out. Quasi-static tensile tests showed that the composites reinforced with CA-treated wood fibers exhibited a significant increase in yield strength (about 30% with a WF amount of 10% at 0 °C) and also a slight improvement in the VICAT softening temperature (about 6 °C with respect to neat PCL). Water absorption tests showed reduced water uptake in CA-treated composites, consistent with the reduced hydrophilicity confirmed by higher water contact angle values. Therefore, the results obtained in this work highlighted the potential of CA-treated WFs as reinforcement for PCL composites, contributing to the development of eco-sustainable and high-performance packaging materials. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2025)

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22 pages, 4758 KiB

Open AccessArticle

Analysis of Interface Sliding in a Composite I-Steel–Concrete Beam Reinforced by a Composite Material Plate: The Effect of Concrete–Steel Connection Modes

by Tahar Hassaine Daouadji, Boussad Abbès, Tayeb Bensatallah and Fazilay Abbès

J. Compos. Sci. 2025, 9(6), 273; https://doi.org/10.3390/jcs9060273 - 29 May 2025

Viewed by 361

Abstract

This study investigates interface sliding behavior in composite I-steel–concrete beams reinforced with a composite material plate by analyzing various connection configurations combining shear stud connectors and adhesive bonding. The degree of composite action, governed by the shear stiffness at the steel–concrete interface, plays [...] Read more.

This study investigates interface sliding behavior in composite I-steel–concrete beams reinforced with a composite material plate by analyzing various connection configurations combining shear stud connectors and adhesive bonding. The degree of composite action, governed by the shear stiffness at the steel–concrete interface, plays a critical role in structural performance. An analytical model was developed based on the elasticity theory and the strain compatibility approach, assuming constant shear and normal stress across the interface. Five connection modes were considered, ranging from fully mechanical (100% shear studs) to fully adhesive (100% bonding), as well as mixed configurations. The model was validated against finite element simulations, demonstrating strong agreement with relative differences between 0.3% and 10.7% across all cases. A parametric study explored the influence of key factors such as interface layer stiffness and composite plate reinforcement material on the overall interface behavior. The results showed that adhesive bonding significantly reduces slippage at the steel–concrete interface, enhancing bond integrity, while purely mechanical connections tend to increase interface slippage. The findings provide valuable guidance for designing hybrid connection systems in composite structures to optimize performance, durability, and construction efficiency. Full article

(This article belongs to the Special Issue Sustainable Composite Construction Materials, Volume II)

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19 pages, 5377 KiB

Open AccessArticle

The Influence of Multi-Walled Carbon Nanotubes on the Pull-Off Strength of Polymer Concrete Overlays on Concrete Substrates with Sulfate Exposure

by Ali Akbarpour, Jeffery Volz and Shreya Vemuganti

J. Compos. Sci. 2025, 9(6), 272; https://doi.org/10.3390/jcs9060272 - 29 May 2025

Viewed by 229

Abstract

Polymer concrete (PC) is recognized for its lightweight nature, wear resistance, and rapid curing, making it well-suited for the repair of deteriorated infrastructure. This research critically addresses the challenge of enhancing overlay adhesion to compromised substrates by uniquely evaluating the role of pristine [...] Read more.

Polymer concrete (PC) is recognized for its lightweight nature, wear resistance, and rapid curing, making it well-suited for the repair of deteriorated infrastructure. This research critically addresses the challenge of enhancing overlay adhesion to compromised substrates by uniquely evaluating the role of pristine versus functionalized multi-walled carbon nanotubes (MWCNTs) in improving polymer concrete (PC) bond strength, particularly on concrete deteriorated by sulfate attack. PC mixtures containing varying concentrations of MWCNTs (0%, 0.25%, and 0.5% by weight) were prepared and tested for their mechanical properties, including compressive strength, modulus of rupture, and pull-off strength. Pull-off tests were conducted to assess the bond between PC overlays and Portland cement concrete (PCC) substrates. To examine the effects of substrate deterioration, PCC specimens were cured under two conditions: standard and sulfate-exposed environments. The results showed that neat polymer concrete (PC-Neat) achieved a high average pull-off strength of 2.82 MPa under normal conditions. Incorporating 0.25% pristine MWCNTs (PC-P25) significantly reduced the bond strength to 0.039 MPa. In contrast, improved performance was observed with functionalized MWCNTs. The addition of 0.5% COOH-functionalized MWCNTs (PC-FC50) yielded a pull-off strength of 2.22 MPa under normal conditions and 1.65 MPa in sulfate environments. Notably, under sulfate exposure, functionalized MWCNTs enhanced the bond strength by up to 15% compared to PC-Neat, highlighting their potential in aggressive environments. This distinct improvement in bond strength presents a significant finding, demonstrating a novel pathway for developing more resilient repair materials for infrastructure exposed to aggressive chemical environments. Full article

(This article belongs to the Special Issue Environmental Degradation of Composites: Microscopic Characterization and Analysis)

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17 pages, 4524 KiB

Open AccessArticle

Prediction of Mechanical and Fracture Properties of Lightweight Polyurethane Composites Using Machine Learning Methods

by Nikhilesh Nishikant Narkhede and Vijaya Chalivendra

J. Compos. Sci. 2025, 9(6), 271; https://doi.org/10.3390/jcs9060271 - 29 May 2025

Viewed by 275

Abstract

This study aims to investigate the effectiveness of two machine learning methods for the prediction of the mechanical and fracture properties of Cenosphere-reinforced lightweight thermoset polyurethane composites. To evaluate the effectiveness of the models, datasets from our experimental study of composites made of [...] Read more.

This study aims to investigate the effectiveness of two machine learning methods for the prediction of the mechanical and fracture properties of Cenosphere-reinforced lightweight thermoset polyurethane composites. To evaluate the effectiveness of the models, datasets from our experimental study of composites made of five different volume fractions (0% to 40%) of Cenospheres (hollow Aluminum Silicate particles) in increments of 10% are fabricated. Experiments are conducted to determine the effect of the volume fraction of Cenospheres on Young’s modulus (both in tension and compression), percentage elongation at break, tensile strength, specific tensile strength, and fracture toughness of the composites. Two machine learning models, shallow artificial neural network (ANN) and the non-linear deep neural network (DNN), are employed to predict the above properties. A parametric study was performed for each model and optimized parameters were identified and later used to predict the properties beyond 40% volume fraction of Cenospheres. The predictions of non-linear DNN demonstrated less slope than shallow ANN and, for mass density, the non-linear DNN had unexpected predictions of increasing mass density with the addition of lighter Cenospheres. Hence, a double-hidden-layer DNN is used to predict the mass density beyond 40%, which provides the expected behavior. Full article

(This article belongs to the Special Issue Lightweight Composites Materials: Sustainability and Applications, Volume II)

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10 pages, 7299 KiB

Open AccessArticle

Molding Process Effects on the Internal Structures of High-Performance Discontinuous Carbon Fiber Reinforced Thermoplastics

by Yi Wan and Jun Takahashi

J. Compos. Sci. 2025, 9(6), 270; https://doi.org/10.3390/jcs9060270 - 29 May 2025

Viewed by 248

Abstract

High-performance discontinuous carbon-fiber-reinforced thermoplastics (CFRTPs) offer promising manufacturing flexibility and recyclability for advanced composite applications. However, their mechanical performance and reliability strongly depend on the internal fiber architecture, which is largely determined by the molding process. In this study, three distinct compression molding [...] Read more.

High-performance discontinuous carbon-fiber-reinforced thermoplastics (CFRTPs) offer promising manufacturing flexibility and recyclability for advanced composite applications. However, their mechanical performance and reliability strongly depend on the internal fiber architecture, which is largely determined by the molding process. In this study, three distinct compression molding approaches—CFRTP sheet molding compounds (SMCs), bulk molding compounds (BMCs), and free-edge molding compounds (FMCs)—were systematically evaluated to investigate how processing parameters affect fiber orientation, tape deformation, and impregnation quality. X-ray micro-computed tomography (XCT) was employed to visualize and quantify the internal structures of each material, focusing on the visualization and quantification of in-plane and out-of-plane fiber alignment and other internal structure features. The results indicate that CFRTP-SMC retains largely intact tape layers and achieves better impregnation, leading to more uniform and predictable internal geometry. Although CFRTP-BMC exhibits greater tape deformation and splitting due to increased flow, its simpler molding process and better tolerance for tape shape distortion suggest potential advantages for recycled applications. In contrast, CFRTP-FMC shows significant tape fragmentation and poor impregnation, particularly near free edges. These findings underscore the critical role of a controlled molding process in achieving a consistent internal structure for these materials for the first time. This study highlights the utility of advanced XCT methods for optimizing process design and advancing the use of high-performance discontinuous CFRTP in industry. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2025)

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24 pages, 5760 KiB

Open AccessArticle

Heat Treatment of Clay Shales and Their Utilization as Active Mineral Additives for the Production of Composite Cements

by Baurzhan Amiraliyev, Bakhitzhan Taimasov, Ekaterina Potapova, Bakhitzhan Sarsenbaev, Meiram Begentayev, Mukhtar Dauletiyarov, Aknur Kuandykova, Aidana Abdullin, Nurzhan Ainabekov and Sultan Auyesbek

J. Compos. Sci. 2025, 9(6), 269; https://doi.org/10.3390/jcs9060269 - 28 May 2025

Viewed by 274

Abstract

A structure of composite cement with 15 wt.% thermally activated clay shales has been developed. The phase composition and properties of aluminosilicate rocks of the Kazakhstan deposits—Mynaral and Kuyuk—have been studied. It has been shown that aluminosilicates are related to clay shales by [...] Read more.

A structure of composite cement with 15 wt.% thermally activated clay shales has been developed. The phase composition and properties of aluminosilicate rocks of the Kazakhstan deposits—Mynaral and Kuyuk—have been studied. It has been shown that aluminosilicates are related to clay shales by their composition. The regularities of thermal activation processes of aluminosilicates have been established, and it has been shown that pozzolanic activity increases for all compositions with an increase in the heat treatment temperature from 700 to 900 °C. The clay shale of the Mynaral deposit is characterized by the highest activity. The physicomechanical properties of the obtained composite cements–including Portland cement clinker, gypsum, and thermally activated clay shale—have been studied. It has been shown that when replacing up to 15 wt.% Portland cement clinker with thermally activated clay shales, there is no decrease in the strength properties of the composite cement. The obtained results allow us to consider heat-treated clay shales as active mineral additives. Full article

(This article belongs to the Section Composites Applications)

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