Mechanical characterization of CFRP/steel bond cured and tested at elevated temperature

Glass transition temperature (Tg) of the bond between CFRP and steel influences on the service and fire performance of strengthened members. A total of eighty-two CFRP/steel double strap joints were prepared and tested under elevated temperature. They were cured under a range of elevated temperature conditions in the control laboratory environment and in the open environment which is practically feasible in large civil engineering structures. The test results showed a similar trend of reductions in the bond strength, Poisson's ratio and Elastic modulus of CFRP/steel joint with the exposure to the elevated temperature. More than 50% reduction in the Poisson's ratio, elastic modulus and the bond strength was noted when the bond line temperature exceeds Tg + 15 °C, irrespective of the curing time and curing conditions. Initial elevated temperature curing also causes for shifting the curves in the right-skewed direction. A significant increase in Tg of bond was noted with 4 h initial curing at 75 °C, i.e. Tg + 20 °C.