Real-time monitoring stiffness degradation of hardened cement paste under uniaxial compression loading through piezoceramic-based electromechanical impedance method

Abstract Real-time health monitoring of cementitious materials under external loadings is of great significance to help engineers evaluate structural safety state and ensure timely maintenance. As a promising nondestructive testing method, the electromechanical impedance (EMI) method has been widely applied in the field of structure health monitoring (SHM) in civil engineering. In this study, this method was explored in monitoring the stiffness degradation of hardened cement paste subjected to compression loadings. Based on the theoretical modelling, a simplified one-dimensional analytical model was established based upon the piezo-elasticity theory to interpret the correlation between the PZT transducer and the cement specimen in the presence of uniaxial compression loading. Moreover, by embedding the PZT transducer inside cement specimens, the conductance signatures in two different frequency ranges throughout the entire loading process were captured and analyzed. It is revealed that the trend of the EMI spectra is compatible with the cement deterioration. More importantly, the resonance frequency and the statistic metric correlation coefficient (CC) can serve as good indicators to quantitatively assess the stiffness degradation of cement paste under uniaxial compression loadings. This research well validates the effectiveness and applicability of the EMI method in real-time monitoring of cement stiffness degradation under compression loadings.