Experimental study on rehabilitation of corrosion-damaged reinforced concrete beams with carbon fiber reinforced polymer

Abstract

The repair and rehabilitation of reinforced concrete (RC) structures in coastal areas is a challenging engineering problem. In order to retrofit the degraded RC structures, numerous studies have been devoted to the method of non-corroded RC components retrofitted with carbon fiber reinforced polymer (CFRP). There is, however, less research available on corroded, patched and CFRP-repaired RC specimens. The purpose of this paper is to investigate rehabilitation of corrosion-damaged RC beams with CFRP, which focus on the effectiveness of CFRP-repaired methods and the effects of CFRP amount on flexural behavior of the beams. In this study, a modified retrofit method based on substrate repairs was developed, which is bonding CFRP after replacing V-notch of substrate concrete with polymer mortar. To compare the modified method with two common retrofit methods, which are respectively bonding directly CFRP and bonding CFRP after replacing damaged concrete, four-point bending experiments were conducted on a series of corrosion-damaged RC beams with CFRP. Important factors were considered in the experimental study, including the number of CFRP layers and corrosion level denoted by the mass loss rate of tensile steel. There were totally 32 RC beams (250mm×150mm×1400mm) constructed in these experiments, 27 of which were corroded by an accelerated aging approach. The results show that the modified retrofit method could provide better load carrying capacity for the beams having more than 15% mass loss of tensile steel. In addition, to improve the short-term performance, the simple method of directly bonding CFRP was suitable for the beams having less than 15% mass loss of tensile steel. It is noted that bonded CFRP could not work for the damaged beams which undertaken more than 50% mass loss of tensile steel. In particular, it is indicated that by optimizing the amount of CFRP, it is possible to balance strength recovery with control of failure mode.