Experimental investigation for GFRP rebar couplers for reinforced concrete

The use of fiber reinforced polymer (FRP) rebars is nowadays becoming popular in reinforced concrete (RC) construction due to their excellent inherent properties such as corrosion resistance, lightweight, and high strength to weight ratio. The steel rebars, being susceptible to corrosion, are being replaced by FRP rebars. The higher strength of FRP rebars, as compared to steel, requires larger lap lengths when embedded in concrete. Although laps in steel rebars can be replaced by mechanical couplers, this is not feasible for FRP rebars. Thus, the present study investigates the use of couplers for Glass FRP (GFRP) rebars. Three types of couplers were tried: (i) steel pipe coupler, (ii) CFRP pipe coupler, and (iii) CFRP sheet coupler. These couplers were tested in direct tension for assessing their feasibility and establishing the design requirements. Although the steel pipe coupler demonstrated excellent performance, the use of CFRP pipe and CFRP sheet couplers were not successful. However, the performance of CFRP sheet couplers can be improved by increasing the length of sheet, and/or number of wraps.