Bond degradation and EMI-based monitoring of CFRP to concrete interfaces exposed to wet-dry cycling

This study aims to examine the bond behaviour of CFRP to concrete interfaces that are exposed to wet-dry (WD) cycling and to explore the applicability of an electromechanical impedance (EMI)-based monitoring method for the bond via the use of piezoelectric transducers (PZTs). Single shear tests were performed on CFRP-concrete interface specimens subjected to a maximum of 360 WD cycles. WD cycling causes a shift in the debonding failure mode from cohesive failure within the concrete to a mixed mode of cohesive failure and adhesive failure. The bond capacity of the conditional specimens did not decrease significantly until 270 WD cycles, indicating that severe bond degradation occurred after 270 WD cycles. Moreover, a generalized method that yields representative evaluation results was applied based on the load response curve, and the bond slip relationship was proposed for the interfaces under WD cycling. In addition, an EMI method that is based on PZTs was employed to monitor the CFRP-concrete interface during exposure to WD cycling and single shear tests. It can be found that EMI monitoring can monitor WD cycling-induced bond degradation and interfacial debonding damage that occurs in single shear tests.