Time-resolved effects of electrolyte chemistry on kaolinite consistency: toward a kinetic, DLVO‑informed interpretation

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4. Time-resolved effects of electrolyte chemistry on kaolinite consistency: toward a kinetic, DLVO‑informed interpretation

Electrolyte - clay interactions strongly influence geotechnical performance because changes in porewater chemistry can modify consistency limits and microfabric evolution in soft soils. These effects are increasingly relevant in environments affected by salinisation, contaminant ingress, and chemically dynamic engineered barriers, yet most predictive models still assume static chemical conditions. This study examines how cation valency, electrolyte concentration, and exposure time influence the Atterberg limits of Speswhite kaolin, toward a time-resolved, DLVO-informed interpretation of kaolinite consistency. Clay pastes were exposed to NaCl, MgCl₂, CaCl₂, and AlCl₃ solutions (0.00 - 0.60 M) for 0.1 - 1000 h prior to testing. Liquid limit (LL) and plasticity index (PI) were measured following standard procedures using repeat and duplicate tests. LL and PI decreased systematically with increasing electrolyte concentration for all salts tested. While multivalent cations produced larger reductions overall than Na⁺, the concentration response did not exhibit a consistent monotonic ranking with cation valency, reflecting the combined influence of ionic strength and ion-specific interactions. A marked transition occurred between 0.20 and 0.60 M, particularly for Ca²⁺- and Al³⁺-treated samples. Time resolved analyses revealed overall negative trends in LL and PI at higher electrolyte concentrations over longer exposure times, with LL reductions reaching up to -1.31 percentage points per decade. At moderate concentrations, multivalent cations exhibited small, non-monotonic time-dependent changes indicative of gradual microfabric rearrangement. These findings highlight the importance of incorporating kinetic chemical effects into models for chemically evolving soil environments.

International Conference on Advances and Innovations in Soft Soil Engineering (ICAISSE2026)

Multiphysics Behaviour