Environment-Assisted Subcritical Debonding of Epoxy-Concrete Interface

Interface debonding can grow slowly within the FRP-to-concrete interface in aggressive environments, even though the energy release rate at the crack tip is only a fraction of the critical energy release rate of the interface. This slow debonding process is called environment-assisted subcritical debonding, which may be a dominant mechanism for the failure of the FRP-to-concrete interface under service loads in aggressive environments. By using wedge-driven testing, this study shows that aggressive environments can substantially increase the debonding growth rate along the epoxy-concrete interface. Fracture surface analysis suggests that the debonding mode can change from the cohesive failure within the concrete in critical debonding to the adhesive failure along the epoxy-concrete interface in subcritical debonding.