Flexural Strengthening of Reinforced Concrete Beams Using Textile-Reinforced Mortar, Carbon Fiber-Reinforced Polymer...

This study conducted an experimental investigation of the flexural behavior of reinforced concrete beams strengthened using externally bonded and near-surface-mounted techniques. The strengthening materials consisted of carbon fiber-reinforced polymer (CFRP) sheets, carbon fiber plates, and textile-reinforced mortar (TRM) with carbon, basalt, and glass textiles, as well as near-surface-mounted (NSM) glass and carbon bars. Twenty-two reinforced concrete beams were tested, comprising one reference specimen and 21 strengthened specimens with different strengthening techniques, numbers of layers, and anchorage conditions. The results showed a marked improvement in the flexural performance of the strengthened specimens compared with the reference specimen, which had an ultimate load capacity of 60.01 kN. CFRP strengthening achieved the highest increase in ultimate load capacity and stiffness, with the best specimen recording 110.44 kN and a stiffness value of 18.83 kN/mm. Carbon fiber plates also exhibited a significant improvement in strength. In contrast, TRM and NSM systems produced comparatively lower strength gains but offered superior ductility and more gradual failure behavior. In terms of TRM strengthening, carbon textiles demonstrated the highest ultimate load capacity, whereas basalt and glass textiles enhanced deformation capacity. The use of fan-type anchors further enhanced the efficiency of externally bonded strengthening systems by delaying premature debonding. Within the scope of the present experimental program, the findings provide a direct comparison of the investigated carbon fiber-reinforced polymer (CFRP), carbon-plate (CP), textile-reinforced mortar (TRM), and near-surface-mounted (NSM) strengthening configurations under identical testing conditions and demonstrate their relative effects on strength, stiffness, ductility, energy dissipation, and failure behavior. These results provide comparative experimental evidence that may assist in selecting strengthening strategies for RC beams with comparable characteristics; however, broader generalization requires consideration of additional member geometries, material properties, reinforcement configurations, and loading conditions.