Experimental and Numerical Investigations of Flexural Strengthening of Reinforced Concrete Beams Using Textile Glass Fabric

Textile-reinforced concrete (TRC) beams have attracted widespread interest in recent years as an alternative to fiber-reinforced polymer (FRP) techniques. However, despite their effectiveness, they are often associated with high material cost, sensitivity to elevated temperatures, and limitations in bonding performance under certain environmental and surface conditions. This research examines incorporating textile reinforcement internally (INT) by supplementing steel bars with glass fiber grids, as well as externally (EXT) by retrofitting existing members. The experimental work evaluates five RC beams: a control (CTR), two INT beams strengthened with alkali-resistant glass fabric textile (AR-GFT), one using one layer (INT1L) and the other three layers (INT3L), and two EXT beams where AR-GFT is bonded with mortar, again with one layer (EXT1L) and three layers (EXT3L). Altogether, 10 beams were tested, with duplicate specimens for every configuration. Observing load-deflection responses, cracking behavior, and the strengthening system’s performance revealed that AR-GFT contributes to enhanced load-bearing resistance in the RC beams. The INT1L beams exhibited negligible improvement compared with the CTR specimen, suggesting that internal strengthening alone does not meaningfully increase strength. Conversely, the INT3L beams demonstrated a 45% rise in strength for one sample, although the second performed similarly to the CTR specimen owing to slippage between the textile and adjacent matrix. EXT3L beams achieved up to a 90% increase in load-bearing capacity in one specimen. Nevertheless, the second specimen exhibited textile layer debonding and performed similarly to the CTR beam, underlining the necessity for correct textile positioning and sufficient mortar impregnation during application. Moreover, a three-dimensional (3D) nonlinear finite-element analysis (FEA) was performed to replicate beam responses, showing strong correlation with experimental observations. Overall, the results indicate that textile-based strengthening systems can successfully retrofit and upgrade RC structures, provided meticulous attention is paid to the quality and execution of the installation process. The study provides new insights into the flexural behavior of textile-strengthened RC beams, particularly in terms of the interaction between internal and external textile reinforcement with conventional steel.