Shear strengthening of RC beams using NSM CFRP bonded using cement-based adhesive

Abstract The shear strength of existing Reinforced concrete (RC) members can be improved by bonding Carbon fibre reinforced polymers (CFRPs) as Near-surface mounted (NSM) or Externally bonded reinforcement (EBR). CFRPs are typically bonded to RC members using epoxy resins which have low glass transition temperatures resulting in poor fire performance. In an effort to improve the fire performance of CFRP strengthened members, researchers have developed Cement-based adhesives (CBAs) and verified their efficacy using NSM CFRP-to-concrete joint tests, however no applications have been conducted on full-scale RC beams strengthened in shear using NSM CFRP and CBA. This study attempts to fill this gap and involves testing fourteen RC beams strengthened in shear using NSM CFRP textile bonded using CBA. The experimental results showed that CFRP textile bonded using CBA in NSM configurations significantly improved the shear capacity of the RC members. Further, comparisons were made between CBA and epoxy resins as bonding agents and it was found that CBA achieved comparable results to epoxy when used in the configuration explored. The results of NSM-CFRP strengthened beams with CBA showed shear strength improvements of 97% and 70% using CFRP textile and laminate, respectively. Therefore, the use of CBA in the NSM CFRP strengthening techniques is considered a good substitute for epoxy resins for bonding CFRP to concrete members.