Electrochemical characterization of internal damage in saline soil under freeze–thaw cycles

The engineering performance of saline soil in high-altitude, cold, and arid regions significantly deteriorates under the actions of freeze–thaw (F–T) cycles. This study systematically investigates the electrochemical characteristics of saline soil with vary contents and types during F–T cycles. The results demonstrate that the electrochemical behavior of saline soil changes with F–T cycles. As the F–T cycles increase, the diameter of the high-frequency Nyquist plot and the volume resistance gradually decrease. Due to the more obvious temperature effect of sodium sulfate compared to sodium chloride, sulfate saline soil exhibit volume expansion, resulting in Nyquist diagrams that differ from those of chloride saline soil. Furthermore, the variation in soil pore structure reflects the F–T damage level in saline soil, which is used to establish an equivalent circuit model. By analyzing the model parameters, a damage index is introduced to quantify the soil damage level, offering a tool for monitoring the evolution of structural damage.