Evaluation of damage and repair rate of self-healing microcapsule-based cementitious materials using electrochemical impedance spectroscopy

In this study, self-healing cementitious materials based on urea-formaldehyde microcapsules were investigated. Electrochemical impedance spectroscopy tests were conducted on specimens with a single crack and a model describing the relationship between the impedance parameters and the degree of damage was established by equivalent circuit fitting. The model was applied to multi-crack specimens that were representative of actual engineering conditions and the coefficients of the model of the multi-crack specimens were determined. Based on this model, the trends of the repair rate for different self-healing times were obtained. The dynamic elastic modulus of all the specimens was tested for verifying the reliability of this model, and the repair rate of the dynamic elastic modulus was calculated according to a similar method. It is found that the repair rate of the dynamic elastic modulus and the damage repair rate were not uniform in value, but with a similar variation trend. The results demonstrated the reliability of the proposed non-destructive method.