Flexural performance of reinforced concrete beams reinforced with hybrid fiber reactive powder concrete

In order to study the retrofitting effects of hybrid fiber reinforced reactive powder concrete (HFRPC), the flexural behaviour of reinforced concrete (RC) beams reinforced with HFRPC was investigated by experiment and theory, then compared with reinforced concrete beams without retrofitting. Seven test beams were designed and made, one of which was not retrofitted, while the other 6 were retrofitted with HFRPC. The test variables include thickness of HFRPC, HFRPC and concrete interfacial bonding method, retrofitting fiber, and so on. The test results show that the reinforced concrete beam strengthened with HFRPC exhibits improved bearing capacity and decreased deformation. The HFRPC retrofitting layer bonds well with concrete, no debonding failure happens. While there are numerous cracks on the HFRPC reinforcement layer, crack width is significantly decreased. Gouged beams have larger bearing capacity than those with troughs. The superior performance of high-strength steel set in HFRPC is fully utilized. Beams with a 40 mm thickness retrofitting layer have larger capacity than 30 mm beams, about 5% better flexural performance. Adopting fiber cloth wraps to retrofit new and old concrete beams can effectively prevent crack propagation, and thus slowing down loss of ultimate load bearing capacity. Through theoretical analysis, a formula for the calculation of HFRPC beam crack load, yield load, and ultimate load is provided. Finally, the experimental results match well with the theoretical predictions. ©, 2015, Editorial Board of Journal of HEU. All right reserved.