Experimental study on durability of CFRP-concrete bond subjected to temperature, humidity and outdoor environment

This paper presents experimental results and observations to-date of an ongoing research undertaken to investigate the long-term behaviour of bond between externally bonded Carbon Fibre Reinforced polymer (CFRP) and concrete. Carbon FRP strips were externally bonded to concrete prisms and were exposed separately to three different environmental conditions, namely, temperature, humidity and outdoor environment for extended durations. Single-lap-joint shear test (pull-out test) was conducted to investigate bond strengths of control (unexposed) and exposed specimens. Moreover, material characterisation of concrete cylinders and CFRP control and exposed coupons was carried out to observe the changes of mechanical properties with the time of exposure. Finally, experimental results of exposed specimens were compared to those of control specimens in terms of bond strengths and failure modes. Based on the results to-date, the most significant degradation of bond strength was observed in specimens exposed to outdoor environment. Whereas no significant effect of temperature cycles were found provided that the temperature is below the glass transition temperature of epoxy resin.