Environment-Assisted Subcritical Debonding of Epoxy-Concrete Interface

Abstract

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. In this study, environment-assisted subcritical debonding of the epoxy-concrete interface was first observed and characterized using wedge-driven testing. Aggressive environments have been found to 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. The proposed subcritical debonding testing closely simulates the failure occurring during the service life of the FRP-to-concrete interface, and allows interaction with environmental species during testing. Subcritical debonding testing provides a new approach to understand the degradation mechanism and to assess the long-term durability of the FRP-to-concrete interface.