Determination of calcium leaching behavior of cement pastes exposed to ammonium chloride aqueous solution via an electrochemical impedance spectroscopic approach

This study employed EIS (electrochemical impedance spectroscopy) as a non-destructive method to study the leaching behavior of the cementitious materials subjected to aggressive environments. A novel electrical equivalent circuit was established based on a microstructure assumption concerning the leaching induced degradation. Electrochemical parameters were extracted from the impedance spectra by fitting the established equivalent circuit. On the basis of the understanding of the physical meanings, a proper equivalent-circuit parameter was defined as the indicator of leaching depth. Then the relationship between the leaching depth and the indicator was estimated. As a result, leaching depths can be quantitatively estimated using EIS method. (C) 2018 Elsevier Ltd. All rights reserved.