Debonding damage detection of the CFRP-concrete interface based on piezoelectric ceramics by the electromechanical impedance method

Debonding in carbon fiber reinforced polymer (CFRP)-strengthened RC structures might always carry the risk of structural collapse. Several studies have focused on the debonding detection of CFRP-strengthened RC structures by nondestructive methods, which represents some limitations. Therefore, an electromechanical impedance (EMI) method based on piezoelectric ceramic (PZT) was applied to detect damage at the CFRP-concrete interface. First, different simulated interfacial defects in a CFRP sheet-wrapped concrete column were detected, and the feasibility of the method was validated. Then, the debonding process of a CFRP plate strengthened RC beam under four-point loading was monitored by the EMI method. Two damage indices, the root mean square deviation (RMSD) and the mean absolute percentage deviation (MAPD), were used to quantify the degree of damage at the CFRP-concrete interface. It is verified that these two damage indices obtained from the EMI method can clearly capture the process of damage development. Moreover, compared to the wave-based method, the EMI method is more sensitive to incipient concrete and debonding damage, which confirms the practicability of the EMI method for on-site applications.