Effect of freeze-thaw cycles on shear resistance of reinforced concrete beams strengthened with UHPFRC

Abstract

Ultra-high performance fiber-reinforced concrete (UHPFRC) has emerged as one of the promising materials for strengthening of concrete structures. For the strengthening application of UHPFRC, one of the primary concerns is to evaluate the degradation of bond behavior and structural re-sponse of strengthened elements under harsh environmental conditions. Therefore, an experi-mental program has been carried out to investigate the interfacial behavior between UHPFRC and normal concrete, as well as the shear performance of UHPFRC-concrete hybrid beams subjected to combined freeze-thaw cycles and mechanical load. In this study, two groups of shear-deficient reinforced concrete beams were first strengthened by UHPFRC precast panels using epoxy resin. Then, the specimens subjected to 0 and 30 freeze-thaw cycles were loaded to failure under three-point bending. The results indicate that the utilization of epoxy resin is an effective bonding tech-nique to ensure the integral performance of the composite beams and the shear capacity is greatly enhanced with the application of UHPFRC. In addition, it is observed that the effect of applied freeze-thaw regime on the UHPFRC-concrete interfacial bond strength and shear resistance of unstrengthened and strengthened beams is negligible.