EMI-based damage evaluation of the recycled aggregate concrete under compressive loading

This study focuses on damage evaluation of the recycled aggregate concrete (RAC) subjected to compressive loading using the electromechanical impedance (EMI) method. To this end, five groups of RAC specimens were prepared with different replacement ratios of recycled coarse aggregate (RCA) for compressive tests under both monotonic and cyclic loading, as well as the EMI tests adopting the embedded PZT smart aggregate (SA) transducer. The influences of RCA content and loading regime on damage process of the RAC were examined in detail based on the test results. In particular, the EMI analysis of SA transducer was theoretically carried out to further explore the general characteristics of admittance curves. Finally, two types of damage indicators were defined based on damage mechanics and the EMI method, respectively. By statistical analysis, correlations between damage indicators were analyzed for different loading regimes and RCA replacement ratios. The results show that damage progress of the RAC under different loading regimes and RCA replacement ratios is generally similar. Besides, correlation coefficient of the conductance curve exhibits the highest correlation with the mechanical damage indicator, making it satisfactory for assessing mechanical damage of the RAC under compressive loading.