Engineering Property of Salt-Contaminated Clay: Mechanistic Insights from Diffuse Double Layer Evolution and Salt Crystallization Effect with Liquid Limit Prediction

DDL compression dominated below the threshold, whereas crystal precipitation subsequently altered pore structure, particle contacts, and water binding. In the NaHCO3 group, the liquid limit increased and then stabilized because alkaline hydrolysis and deprotonation promoted DDL expansion and particle dispersion, whereas subsequent crystallization restricted further expansion. In the NaCl group, the liquid limit generally decreased because increasing ionic strength compressed the DDL and promoted particle flocculation.

Salt-specific semi-empirical prediction models were further developed using DDL evolution and salt crystallization effect as the primary controlling factors, achieving R² values above 0.96. Overall, this study elucidates the physicochemical mechanisms governing salt-dependent liquid limit evolution and provides a practical approach for predicting the liquid limit of salt-contaminated clay.