Performance evaluation of strengthened concrete beams: flexural and shear enhancement using chopped strand and woven roving mats

Concrete, the most widely used construction material, is inherently strong in compression but deficient in tension. This study investigates the effectiveness of externally bonded glass fibre composites namely chopped strand mats (CSM), woven roving mats (WRM), and combined wrapping in a U-shaped wrapping scheme to enhance the flexural and shear performance of reinforced concrete (RC) beams. For specimen preparation, Ordinary Portland Cement (53 grade), natural river sand, granite coarse aggregate, and high-strength cold-twisted reinforcement bars were employed, while the fibre sheets were bonded using epoxy resin. A total of eight beams were cast and grouped into flexural and shear categories, each consisting of a control specimen and beams strengthened with single-layer CSM, WRM, and hybrid CSM + WRM wrapping. Experimental evaluation was carried out under two-point loading for flexural beams and near-point loading for shear beams, focusing on load-deflection response, moment-curvature behaviour, stiffness degradation, and crack propagation. The results demonstrate that fibre wrapping significantly delayed crack initiation and improved energy absorption capacity. Flexural beams exhibited ultimate load enhancements from 18.6 kN for the control (FBO) to 23.6 kN (+ 21.18%), 27.2 kN (+ 31.62%), and 31.84 kN (+ 41.58%) for CSM, WRM, and CSM + WRM strengthened beams, respectively. Similarly, shear beams improved from 18.6 kN for the control (SBO) to 24.0 kN (+ 22.5%), 25.2 kN (+ 26.19%), and 28.32 kN (+ 34.32%) for the corresponding strengthening configurations. The findings confirm that U-shaped hybrid wrapping with CSM and WRM provides superior strengthening efficiency, offering substantial improvements in both flexural and shear capacities compared with single-layer applications.