Characterization of internal damage of concrete subjected to freeze-thaw cycles by electrochemical impedance spectroscopy

In this work, internal damage condition of concrete subjected to freeze-thaw (F-T) cycles was investigated by means of electrochemical impedance spectroscopy (EIS) technique. The equivalent circuit model was adopted to explain the EIS results according to the establishment of physical model simulating the internal micro structure of concrete. As a result, continuous decrease of resistance of continuous path was found out in the process of F-T cycle because of the expansion and propagation of internal cracking of concrete. This was also demonstrated by microscopic analysis obtained from environmental scanning electron microscope (ESEM) observation. Besides, damage degree calculated based on the decrease of resistance was introduced to evaluate the internal degradation condition of concrete suffering from F-T cycles.