Electrochemical impedance measurement and modeling analysis of the carbonation behavior for cementititous materials

In this paper, electrochemical impedance spectroscopy (EIS) was adopted as a nondestructive testing method for studying the carbonation behavior of the cementitious materials. A newly proposed electrochemical model was used to explain the carbonation related phenomenon. Results of the micro-morphology observation were obtained to evaluate the reliability and the accuracy of the model. The experimental results demonstrate that the porous structure of the cement changes and porosity of the cement reduces during the carbonation process. With the increase of the water/cement ratio, the internal porosity increases, resulting in even more remarkable carbonation. The carbonation can be quantitatively analyzed by the parameters fitted from the electrochemical model based on EIS. It was found that the fitted parameter has direct function related to carbonation time and carbonation depth. As a result, it is possible to predict carbonation depth quantitatively.