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Integrating machine learning with experimental data to predict tensile strength of cement pastes with binary cementitious systems
(2026-07-01)
Khan, Ameer Murad
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Hussain, Qudeer
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Mohamad, Hisham
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Jirasakjamroonsri, Amornthep
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Anotaipaiboon, Weerachai
This study demonstrates a concerted experimental and machine learning model to determine the direct tensile strength of cement pastes with the addition of supplementary cementitious materials (SCM) used as binary cementitious systems. Five types of SCM were used as single binary substitutes at levels of 5–25 % each to form a complete experimental database of 135 cement paste mixtures at water-cement ratios of 0.30–0.40, respectively, to provide a systematic and applied evaluation of the individual contribution of each material to tensile performance. Briquette tests were used to measure direct tensile strength at the binder level to isolate behaviour. Ten mix design parameters were used to train six machine learning regressors (Decision Tree, Random Forest, Gradient Boosting, XGBoost, CatBoost and Support Vector Regression) to predict tensile strength. Support Vector Regression and XGBoost had the best predictive accuracy with R<sup>2</sup> that reached 0.88 and lowest RMSE of 3.3. Analysis of feature importance and partial dependence indicated that the dominant predictors were the water-cement ratio, cement content, and dosage of fly ash and silica fume had a small optimal replacement range, which is in line with the experimental data. The existence of a correspondence between the trends of machine learning and the known hydration mechanisms proves the physical plausibility of the models. The most successful model was an interactive web based tool, TensAile-Lab, to be used in support of fast, data-driven mix design decisions. The suggested framework illustrates the use of interpretable machine learning to forecast tensile behavior with high reliability and speed up the creation of optimized, low-carbon cementitious systems.
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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 (R<sup>2</sup> = 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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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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Data-driven prediction of failure loads in low-cost FRP-confined reinforced concrete beams
(2025-07-01)
Talpur, Shabbir Ali
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Thansirichaisree, Phromphat
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Anotaipaiboon, Weerachai
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Mohamad, Hisham
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Zhou, Mingliang
This study investigates the application of machine learning (ML) models to predict the ultimate failure load of reinforced concrete (RC) beams confined with low-cost fiber-reinforced polymers (FRP), relatively underexplored area. A dataset of 100 samples, including beams designed to fail in flexure and shear, was compiled from literature and experimental testing. Four ML models—XGBoost, Random Forest (RF), Neural Network (NN), and Decision Tree (DT)—were evaluated using k-fold cross-validation with performance metrics such as Mean Absolute Error (MAE), Mean Squared Error (MSE), Root Mean Squared Error (RMSE), and R². XGBoost outperformed the other models, achieving the highest R² of 0.96 and the lowest RMSE of 12.81, while SHAP analysis identified beam height, bottom rebar strength, and beam width as key predictors. These results highlight the effectiveness of ensemble methods for predicting failure loads in RC beams and provide insights into the most influential features affecting structural performance.
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Hybrid B-CSM Composites Strengthening Approach for Improved Stress–Strain Behavior of Concrete Columns and Development of Analytical Models
(2025-02-01)
Thansirichaisree, Phromphat
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Mohamad, Hisham
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Zhou, Mingliang
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Ejaz, Ali
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Saingam, Panumas
The brittle behavior of concrete under axial compressive loading has been a persistent issue. This study investigates the effectiveness of a hybrid Basalt-E-glass confinement (B-CSM) in improving the compressive behavior of concrete. The B-CSM confinement demonstrates a considerable improvement in ultimate strength and strain capacity by over 250 and 500%, respectively, making it a favorable solution for enhancing the ductility of concrete structures. Specimens at 18.43 MPa unconfined strength, confined with 3-layer B-CSM, demonstrated a 258% ultimate strength enhancement. For 24.43 MPa specimens, the same confinement resulted in a 207% increase in ultimate strength. Specimens with an initial ultimate strain of 18.43 MPa, when confined with 3-layers, showed a notable 516% increase. Likewise, for 24.43 MPa specimens, the same confinement led to a significant 395% improvement in ultimate strain. The use of B-CSM confinement is also effective in terms of cost compared to synthetic fiber-reinforced polymer jackets, and its availability is widespread. Existing analytical models for fiber-reinforced polymer confinement were evaluated, and it was found that these models could not predict the ultimate strength and strain of B-CSM-confined concrete. Therefore, this study proposes a unique regression-based approach for predicting the various points of the compressive stress vs. strain curve of B-CSM confinement. These points are then used to trace the complete stress vs. strain curve, which matches closely with experimental results. This work contributes to the development of new design recommendations for B-CSM confined concrete structures, which can enhance the performance of concrete structures and potentially reduce construction costs.
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Performance of Environmentally Friendly Concrete Containing Fly-Ash and Waste Face Mask Fibers
(2024-12-01)
Nawaz, Adnan
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Khan, Ameer Murad
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Jirasakjamroonsri, Amorntep
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Saingam, Panumas
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Ejaz, Ali
This work was carried out to explore the potential use of used face masks in concrete to develop sustainable green concrete. In this experimental study, used face masks were cut up, removing the ear stripes and internal nose steel wire, to prepare elongated fibers. These fibers were incorporated in cement fly ash mixtures as an additive to determine the response of M20-grade concrete. The Class F fly ash (FA) was employed as a fractional substitute of cement up to 25% by weight, whereas the addition of face masks occurred at 0%, 0.125%, and 0.25% by volume of concrete. The testing scheme focused on the mechanical and durability characteristics of the cement FA mixtures carried out after 3, 28, and 60 days of curing. The inclusion of FA and face mask fibers reduced the density of concrete specimens. The compressive, splitting tensile, and flexural strengths of mixes were also reduced at an early age; however, the strength characteristics improved at later ages, compared to the control mix. The combination of both materials in concrete mixtures resulted in lower water absorption, lower bulk water sorption, and lower mass loss values against acid attack at later ages. Similarly, the electrical resistance of concrete substantially enhanced by increasing the percentage of both materials. The experimental results demonstrated that processed face masks can be utilized in cement fly ash mixes without significantly compromising the resultant concrete characteristics.
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Stress-strain behavior of square concrete columns confined with hybrid B-CSM composites and development of novel prediction models
(2024-07-01)
Thansirichaisree, Phromphat
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Mohamad, Hisham
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Ejaz, Ali
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Saingam, Panumas
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Hussain, Qudeer
This paper presents a comprehensive investigation into the behavior of concrete confined with hybrid Basalt and Chopped Strand Mat (B-CSM) fibers. The newly proposed B-CSM confinement technique substantially enhances the brittle compressive stress-strain behavior, leading to a noteworthy increase in peak strength (approximately 90%) and ultimate strain (approximately 461 %). The efficiency of B-CSM confinement is affected by the strength of plain concrete, with lower-strength specimens indicating a more pronounced enhancement. The performance of existing analytical models for FRP confinement in predicting ultimate strength and strain in B-CSM confined concrete is assessed, highlighting the need for tailored models. Regression-based equations are proposed for characteristic points along the stress-strain curve, enabling accurate prediction of material behavior. The predicted stress-strain curves exhibit a high level of agreement with experimental results. These findings provide valuable insights for the design and application of B-CSM confinement techniques in structural engineering, facilitating improved performance and ductility of concrete structures under compressive loading conditions.
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Machine learning approach to predict the strength of concrete confined with sustainable natural FRP composites
(2024-07-01)
Ali Talpur, Shabbir
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Thansirichaisree, Phromphat
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Poovarodom, Nakhorn
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Mohamad, Hisham
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Zhou, Mingliang
Recent earthquakes have highlighted the need to strengthen existing structures with substandard designs. NFRPs provide a sustainable, cost-effective alternative for strengthening, but accurately predicting their performance remains a challenge. This study investigates the use of machine learning algorithms for predicting the compressive strength concrete specimens confined with various NFRPs. Four algorithms were employed: decision tree, random forest, neural network, and gradient boosting regressor. A diverse dataset encompassing various geometries, material properties, and confinement configurations was used to train and evaluate the models. Gradient boosting regressor (GBR) achieved the highest performance, with an average R-squared value of 0.94 and low mean absolute error (MAE) and root mean squared error (RMSE) during training and k-fold cross-validation. Neural network and random forest also demonstrated satisfactory performance, with average R-squared values of 0.88 and 0.86, respectively, during cross-validation. These results suggest that machine learning holds promise for predicting the compressive strength of concrete confined with NFRPs. GBR offers the most accurate predictions, making it a valuable tool for engineers seeking to optimize the design and performance of strengthened structures using sustainable materials.
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Behavior of shallow concrete beams strengthened using low-cost GCSM and mechanical anchors
(2024-01-01)
Thansirichaisree, Phromphat
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Mohamad, Hisham
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Zhou, Mingliang
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Ejaz, Ali
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Saingam, Panumas
This study aimed to evaluate the shear strengthening capabilities of reinforced concrete (RC) shallow beams constrained by externally bonded glass chopped strand mat (GCSM) sheets and metallic mechanical anchors. The research investigated the effectiveness of GCSM sheets, known for their cost-effectiveness, ease of installation, and absence of specialized labor requirements, in improving the shear capacity, energy dissipation, and deformation capacity of RC beams. Experimental results revealed that GCSM sheets significantly enhanced the deformation capability, ultimate shear strength, and energy dissipation of RC shallow beams. Beams with GCSM applied to both the sides and bottom (SB) configuration demonstrated higher load-bearing capacity and energy dissipation compared to beams with GCSM only on the sides. The incorporation of a metallic mechanical bolt anchorage (MBA) system reduced the load-carrying capacities of beams with SB and beams with GCSM applied to only side by 28% and 5%, respectively, due to the drilling required for installation. However, the MBA system significantly improved the deflection performance, with beam B-S-A (GCSM on sides only and supplemented with MBA exhibiting the highest ultimate deflection of 23.92 mm. Overall, beams equipped with the MBA system showed superior ultimate deflection compared with those without it. Despite some reductions in load-bearing capacity, GCSM sheets combined with MBA systems proved highly effective in enhancing the shear strength, energy dissipation, and deformation capabilities of RC shallow beams, making them a valuable alternative for shear strengthening applications.
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Influence of natural fiber rope wrapping techniques on the compressive response of recycled aggregate concrete circular columns
(2023-09-01)
Chaiyasarn, Krisada
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Poovarodom, Nakhorn
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Ejaz, Ali
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Ng, Anne W.M.
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Hussain, Qudeer
The utilization of recycled waste in the production of new concrete raises significant concerns regarding the quality of the resulting concrete. One prominent drawback of recycled aggregate concrete (RAC) is its inferior mechanical properties compared to natural aggregate concrete. In this study, we examine the impact of hemp fiber rope (HFR) confinement on improving the compressive stress-strain behavior of RAC, specifically using recycled brick aggregates from fired-clay solid bricks (RAC-FCSB) as a partial substitute for natural coarse aggregates. Furthermore, we explore and compare the effectiveness of HFR confinement in the form of strips versus fully wrapped confinement. To conduct the experiments, a comprehensive framework was developed, involving a total of 32 cylindrical specimens. The parameters of interest included the configuration of HFR confinement (strips or full wrapping), the number of HFR layers, and the inherent strength of the concrete. The results indicate that HFR strips can significantly enhance the compressive stress-strain response. However, their performance falls short when compared to the fully wrapped HFR confinement. Nonetheless, HFR strips were able to enhance the peak compressive stress and strain of RAC-FCSB up to 204% and 190%, respectively. The second part of the study investigated the performance of existing models of HFR confinement in predicting the peak compressive stress and strain of RAC-FCSB. The deficiencies in existing models were highlighted, and new models based on non-linear regression analysis were proposed to accurately predict the peak compressive stress and strain of HFR-confined RAC-FCSB.

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