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Experimental evaluation of sustainable jute–basalt hybrid FRP systems for flexural strengthening of RC beams with variable wrapping and light-weight aggregate replacement
(2026-12-01)
Saingam, Panumas
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Hanif, Muhammad Adnan
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Ahmed, Fahad
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Chatveera, Burachat
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Sua-iam, Gritsada
This research experimentally assesses the flexural strengthening of reinforced concrete (RC) beams through the use of sustainable jute–basalt (JB) hybrid fiber-reinforced polymer (FRP) systems with variable wrapping schemes and lightweight aggregate (LWA) replacement. A total of 18 beams with identical geometry and reinforcement were tested under four-point bending, including controls, basalt FRP (BFRP), jute FRP (JFRP), and hybrid JB FRP systems in bottom-only, U-wrap, and full-wrap configurations. The results indicate that FRP confinement significantly modified failure modes, transitioning from the brittle crushing in controls to rupture- or debonding-controlled mechanisms. BFRP significantly enhanced strength, achieving up to 36.8% greater capacity in full-wrap beams, while JFRP improved ductility but was more prone to premature debonding. Hybrid JB FRP systems demonstrated the most balanced performance, with U-wrap hybrids achieving 39.6% higher load capacity and maintaining significant deformation capacity even in LWA concrete. Load–strain responses confirmed yielding of steel reinforcement in all cases, though maximum strains were reduced after confinement due to premature fiber debonding or rupture at smaller deflections. The use of LWA reduced ductility of control beams, but hybrid U-wrap systems successfully compensated for this limitation, providing the highest load and deflection values among all specimens. These results emphasize the potential of hybrid natural–mineral FRP systems as sustainable alternatives to synthetic composites, providing competitive ductility and reinforcement for structural retrofitting applications in both conventional and lightweight concretes.
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Cost-effective FRP solutions for enhancing strength and strain of sustainable concrete made with waste tyre rubber
(2026-12-01)
Saingam, Panumas
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Chatveera, Burachat
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Hussain, Qudeer
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Sua-iam, Gritsada
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Chaimahawan, Preeda
This study investigates the compressive behavior and analytical modeling of natural and rubberized concretes confined with cost-effective glass fiber-reinforced polymer (GFRP) jackets. Forty-two cylindrical specimens were tested under axial compression, including natural aggregate concrete (NAC) and rubberized concretes (RuC) prepared with 20% fine aggregate replacement using coarse (2.0 mm) and fine (0.425 mm) waste tire rubber. Both full and strip GFRP wrapping configurations with two, four, and six layers were examined. The results showed that GFRP confinement substantially enhanced both strength and ductility, transforming brittle failure into a gradual, energy-absorbing response. Full wrapping produced up to 63% and 90% strength increases for NAC and rubberized concretes, respectively, with ultimate strain gains exceeding 1300% in the fine-rubber mix. Strip wrapping achieved moderate yet significant improvements while offering material savings. Analytical models were developed for both concrete types to predict confined stress–strain behavior, achieving strong correlations (R2 = 0.84–0.99) between predicted and experimental data. The derived regression-based formulations successfully captured the influence of confinement pressure, rubber content, and wrapping configuration. These findings demonstrate that GFRP provides an economical and sustainable confinement solution for enhancing the performance of rubberized concrete in structural and retrofitting applications.
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Evaluating the shear capacity of reinforced concrete beams retrofitted with hybrid FRP composite techniques: experimental and analytical study
(2026-07-01)
Joyklad, Panuwat
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Chatveera, Burachat
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Sua-Iam, Gritsada
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Chaimahawan, Preeda
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Suthumma, Chisanuphong
This study investigates the shear performance of reinforced concrete (RC) beams strengthened with externally bonded hybrid fiber-reinforced polymer systems. The strengthening materials include mild steel strips, glass chopped strand mat (GCSM) fiber-reinforced polymer (FRP) composites, natural basalt fiber-reinforced polymer (BFRP) composites, and hybrid combinations of GCSM and BFRP. The hybrid systems pair low-strain GCSM composites with higher-strain natural BFRP to improve both strength and ductility. Eleven RC beams were tested and compared to a control specimen that lacked shear reinforcement over half the span. All strengthened beams showed substantial improvements over the unstrengthened control (35.49 kN). Peak loads ranged from 59.94 kN to 144.86 kN, corresponding to increases of approximately 69–308% relative to the control. In term of deflections again peak load, strengthening increased deflections by roughly 4.4–10.5 times versus the control beam. Strip orientation and layering strongly influenced crack redistribution and energy dissipation. The hybrid GCSM–BFRP systems provided a balanced improvement in strength and post-peak behavior.These results indicate that steel-strip and composite-based strengthening approaches offer affordable and effective solutions for retrofitting shear-deficient RC elements, particularly in post-disaster or resource-limited settings.
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Temperature-resilient performance of hemp rope–Confined recycled aggregate concrete in axial compression
(2026-07-01)
Thansirichaisree, Phromphat
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Ejaz, Ali
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Chaimahawan, Preeda
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Hussain, Qudeer
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Jirasakjamroonsri, Amornthep
This study addresses the growing need for sustainable and cost-effective alternatives to conventional fiber-reinforced polymer (FRP) confinement systems, particularly for recycled aggregate concrete (RAC) subjected to elevated temperatures. The axial compressive behavior of hemp rope-confined RAC cylinders was experimentally investigated under ambient and moderate thermal exposure (150°C). Two strength grades were considered, with confinement applied using one to three layers of hemp rope. The results demonstrate that hemp confinement significantly enhances both compressive strength and axial strain, with improvements increasing with the number of layers, while strain enhancement was consistently more pronounced than strength gain. The stress–strain response exhibited a characteristic two-stage behavior, consisting of an initial unconfined-like region followed by a confinement-activated ascending branch. The elastic modulus of RAC was found to be approximately 21.9% to 29.7% lower than ACI 318-19 predictions, suggesting a reduction factor of about 25% for practical applications. Thermal exposure had a limited effect on normalized strength and strain parameters, although post-peak stiffness showed some sensitivity. Notably, confinement proved even more effective in thermally damaged specimens due to increased lateral deformability. A regression-based analytical model was developed to predict the complete stress–strain response, showing close agreement with experimental results. This study is among the first to evaluate the performance of hemp rope confinement for RAC under elevated temperature conditions and to propose a unified predictive framework. Overall, the findings confirm that hemp rope confinement is an effective, sustainable, and reliable technique for enhancing both the strength and ductility of RAC, with strong potential for structural applications, including post-fire rehabilitation.
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Advancing Masonry Engineering: Effective Prediction of Prism Strength via Machine Learning Techniques
(2026-04-01)
Saingam, Panumas
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Chatveera, Burachat
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Nawaz, Adnan
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Ali, Muhammad Hassan
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Choudhary, Sandeerah
Masonry buildings have shaped construction history since about 6500 BCE. They offer durability, strength, and cost effectiveness, especially in developing countries. Yet assessing compressive strength during construction remains challenging due to the constituent materials soil, cement, and stone, complicating standardization worldwide. In the present study, an innovative model based on a machine learning algorithm is put forth to predict the compressive strengths of prisms. Some important factors considered as input to the algorithm based on traditional methods are the brick and mortar strengths, prism geometry, mortar bed thickness, and empirically derived height-to-thickness (t) (h/t) ratios. Three different ANN algorithms are coded and trained on the input data, and they are based on the Levenberg–Marquardt algorithm, the resilient backpropagation algorithm, and the conjugate gradient algorithm. The optimal ANN model trained using the conjugate gradient Polak–Ribière algorithm (traincgp) achieves superior performance, with R2 = 0.9881, R2 = 0.9927, RMSE = 0.9914 MPa, MAE = 0.6039 MPa, MAPE = 20.9141%, VAF = 0.9881, and WI = 0.9970. Sensitivity analysis shows the height-to-thickness (h/t) ratio is the dominant influence on compressive strength, consistent with structural mechanics. The primary contributions are the systematically curated, richly parameterized dataset and its use to produce robust, physically interpretable predictions with established ANN methods.
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From Experiment to Prediction: Machine Learning Solutions for Concrete Strength Assessment with Steel Clamps
(2026-02-01)
Saingam, Panumas
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Chatveera, Burachat
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Sua-Iam, Gritsada
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Chaimahawan, Preeda
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Suthumma, Chisanuphong
This study examines the confined compressive strength (Fcc) of circular, square, and rectangular column geometries under varying confinement conditions. Results indicate that circular columns have the highest Fcc values, exceeding those of square and rectangular shapes. Increased confinement through clamps significantly enhances compressive strength. Five machine learning models, Linear Regression, Decision Tree, Random Forest, AdaBoost, and Gradient Boosting, were used to predict Fcc based on geometric and confinement parameters. Linear Regression and Decision Tree models achieved moderate predictive performance, with R2 values of 0.84 and 0.83, respectively, and relatively higher error measures (RMSE, MAE, and MAPE), indicating limited ability to capture complex nonlinear relationships in the data. In contrast, ensemble-based methods demonstrated superior performance. The Random Forest model improved the coefficient of determination to 0.90 while substantially reducing all error metrics, reflecting enhanced generalization through bagging. The boosting-based approaches yielded the best results, with AdaBoost achieving the highest R2 value of 0.99 and the lowest RMSE, MAE, and MAPE among all models, followed closely by Gradient Boosting with an R2 of 0.98. These results confirm that ensemble learning techniques, particularly boosting algorithms, yield more accurate and robust predictions than single learners for the problem studied. Data visualization techniques, including Regression Error Characteristic curves (REC) and SHapley Additive exPlanations (SHAP) value analysis, highlighted model performance and feature importance, emphasizing the roles of confinement and geometry in compressive strength. This research demonstrates the potential of machine learning to optimize structural engineering design and suggests further exploration of alternative shapes and confinement strategies to enhance structural integrity.
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Eco-Friendly Structural Solutions: The Synergy of Waste Rubber and Hemp Fibers in Sustainable Concrete Design
(2026-01-01)
Thansirichaisree, Phromphat
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Mohamad, Hisham
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Chaimahawan, Preeda
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Hussain, Qudeer
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Jirasakjamroonsri, Amornthep
The growing emphasis on sustainable construction has encouraged the integration of recycled and renewable materials into structural concrete. This study investigates the axial compressive behavior of rectangular columns incorporating waste-tire rubber as a partial replacement of fine aggregate (5% and 10%) and external confinement using low-cost hemp ropes. A total of twelve specimen configurations, including unconfined and hemp-confined columns with up to three wrapping layers, were tested under monotonic axial compression. The results show that rubber inclusion reduces initial stiffness and peak strength by up to 46%, yet significantly enhances deformability. Hemp-rope confinement effectively compensates for strength loss, increasing compressive strength by up to 53% and ultimate strain by over 500%, with more pronounced effects in rubberized mixes. Normalized strength and strain trends demonstrate a strong dependence on confinement ratio, particularly for highly deformable concrete. To generalize these behaviors, Popovics-based models were calibrated using nonlinear regression, yielding high predictive accuracy (R2 = 0.94–0.98) for key parameters including peak stress, peak strain, post-peak modulus, and elastic modulus. The proposed expressions closely reproduce the experimental stress–strain response and provide practical tools for modeling confined conventional and rubberized concrete.
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Axial compressive performance of sustainable BFRP-confined rectangular columns using recycled brick aggregates
(2025-10-01)
Suthumma, Chisanuphong
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Ejaz, Ali
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Iqbal, Muhammad Jawed
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Yooprasertchai, Ekkachai
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Hussain, Qudeer
This study examines the mechanical behavior of basalt FRP confined rectangular concrete columns using crushed brick aggregates, addressing a research gap. While previous work focused on circular and square columns, this is the first to explore rectangular ones. The use of waste brick aggregates promotes sustainability. The study aims to assess the mechanical properties, expecting improvements in strength and ductility, and could lead to broader applications of basalt FRP. A total of 32 rectangular specimens were tested to evaluate the influence of aggregate type, concrete grade, and number of BFRP layers (0, 2, 4, and 6) on axial compressive performance. Results showed that BFRP confinement significantly enhanced strength and ductility, with maximum gains of 81% in strength and 230% in strain observed in low-strength natural aggregate concrete. Although recycled brick aggregate concrete (RBAC) exhibited lower stiffness, BFRP still provided up to 23% strength improvement. The effectiveness of confinement reduced with increasing unconfined strength. Post-peak analysis revealed that additional BFRP layers delayed stiffness degradation, promoting more ductile failure. Experimental elastic modulus closely matched ACI predictions in natural aggregate (NA) specimens but was overestimated in RBAC due to its higher porosity. The findings demonstrate the viability of BFRP confinement for enhancing the structural performance of sustainable concrete, while emphasizing the need for aggregate-specific design considerations. Design-oriented modelling was adopted to predict the complete stress-strain response of BFRP-confined concrete incorporating both natural and recycled brick coarse aggregates. A two-branch idealization of the compressive response was performed. Several key points were identified and predicted by using nonlinear regression analysis. The proposed approach closely predicted the response of BFRP-confined concrete.
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Green reinforcement techniques: Using natural hemp and cotton ropes to enhance the structural integrity of short-span RC beams
(2025-09-01)
Thansirichaisree, Phromphat
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Ejaz, Ali
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Saingam, Panumas
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Mohamad, Hisham
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Hussain, Qudeer
This study evaluates the structural performance of natural fiber ropes—hemp and cotton—as sustainable strengthening materials for short-span reinforced concrete (RC) beams. A total of 15 beams were tested under four-point bending: one unstrengthened control beam and 14 strengthened beams divided into three groups. Group I included three cotton-strengthened beams using two strip configurations (Type A: 50 mm wide, Type B: 100 mm wide) and one full wrap (Type C). Group II comprised nine hemp-strengthened beams reinforced with 1, 2, or 3 layers in various configurations, while Group III included two CFRP-strengthened beams using a single layer of CFRP strips (Types A and B). Beams strengthened with a single cotton or hemp rope layer exhibited inadequate shear resistance, showing concrete crushing or diagonal cracking. In contrast, two-layer hemp confinement led to more vertical cracking, indicating improved ductility. Results showed that cotton- and hemp-strengthened beams improved peak load capacity by 17 %–40 % and 22 %–78 %, respectively, compared to the control beam, while CFRP offered 36 %–51 % gains. Deflection capacity, indicating ductility, increased by 58 %–95 % for cotton, 42 %–155 % for hemp, and 71 %–145 % for CFRP. Full wrap configurations consistently provided the highest enhancements in both load and ductility, while among strip configurations, Type B outperformed Type A. Hemp ropes delivered higher load capacity due to their superior tensile strength, whereas cotton ropes exhibited greater ductility because of their higher fracture strain (13.5 % vs. 3.5 %). Energy dissipation improved with increased rope quantity and tighter strip spacing. The study also found that conventional FRP-based shear prediction models significantly overestimated the contribution of hemp confinement due to its larger diameter (2.1 mm), underscoring the need for revised modeling approaches. These findings demonstrate the technical feasibility, cost-effectiveness, and environmental advantages of using natural fiber ropes as alternative strengthening materials in structural retrofitting.
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Influence of recycled electronic waste fiber on the mechanical and durability characteristics of eco-friendly self-consolidating mortar incorporating recycled glass aggregate
(2025-07-01)
Saingam, Panumas
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Chatveera, Burachat
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Roopchalaem, Jutatip
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Hussain, Qudeer
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Ejaz, Ali
In the paper, the sustainable production of eco-friendly self-consolidating mortar (SCM) is explored with waste glass as a partial and complete substitution for fine aggregate owing to crucial environmental concerns. For that, the waste glass was replaced at 0 %, 25 %, 50 %, 75 %, and 100 %, while electronic waste fibers were added at 5, 10, and 15 % levels. Results showed that mini slump flow values varied between 233 mm and 263 mm, which confirmed the self-consolidating properties of the material even at 100 % replacement of fine aggregates and an addition of 15 % fiber. The increase in waste glass replacement reduced compressive strength; notably, a 30 % decrease was identified at the maximum substitution level of 100 %. Meanwhile, the mixtures incorporating 5 % fibers demonstrated the highest compressive strength at all maturation periods and replacement levels, even more markedly than the control mixture. The water absorption also increased significantly with increasing waste glass levels, up to 28.87 % at 100 % replacement, indicating increased porosity. Thermal conductivity decreased substantially, ranging from 1.97 W/mK for the control to 1.39 W/mK for 100 % replacement, which could be considered an improvement in insulation properties. These results show the possibility of using waste glass and electronic waste fibers to develop green SCM with enhanced thermal insulation and optimized mechanical properties.

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