Corrosion Sensor for Monitoring the Service Condition of Chloride-Contaminated Cement Mortar

A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (R-p) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (R-s). The results show that the polarization resistance is related to the chloride content and R-s; ln (R-p) is linearly related to the R-s values in mortar without added chloride. The relationships observed between the R-p of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that R-s can indicate the corrosion state of concrete structures.