Flexural strengthening of reinforced concrete beams using textile-reinforced mortar improved with short PVA fibers

Abstract

Textile-reinforced mortar (TRM) composites were developed to avoid the problems caused by fiber-reinforced polymer (FRP) composites. Furthermore, short and dispersible polyvinyl alcohol (PVA) fibers were applied in TRM matrix to improve the brittle behavior and limit the crack width of TRM composites. In this study, eight reinforced concrete (RC) beams, including two reference beams and six strengthened beams, were designed to investigate the flexural behaviors of RC beams strengthened with PVA fibers-improved TRM composites. The investigation variables were (i) the longitudinal steel bar ratio, (ii) the carbon textile reinforcement ratio, and (iii) the sustaining load level. The test results indicated that (1) TRM composites could effectively limit the crack width of RC beams, and multi-crack behavior was observed in the strengthening overlay. (2) The flexural capacity of strengthened beams was enhanced as the number of textile layers increased. This enhancement came with a decrease in deformation, energy absorption, and ductility to some extent depending on the failure modes. (3) For strengthened RC beams with the sustaining load of 60kN and 96kN, the yield load was decreased by 8% and 16% respectively compared with the strengthened beam without the sustaining load. The enhancement efficiency in yield load was reduced as the sustaining load level increased. However, an acceptable reduction in ductility was obtained. Finally, based on the plane section assumption, an analytical mode was proposed to calculate the flexural capacity and deflection of RC beams strengthened with TRM composites.