Shrinkage and soil water retention characteristics of undisturbed soft sensitive clay after electroosmosis treatment

Abstract

The availability of low-cost and renewable electricity in Finland has encouraged practitioners to explore electroosmosis for consolidating soft clay. However, the shrinkage and soil water retention characteristics of soft sensitive clays after application of electroosmosis remain underexplored. Current study presents the laboratory electroosmotic dewatering experiments conducted on meticulously sampled undisturbed Finnish clays. The hydraulic properties, consolidation potential, shrinkage curves, and soil water retention characteristics, along with the electro-chemical changes, were evaluated at 10, 20, and 30 V. Electroosmotic treatment resulted in a two-order magnitude (10²) increase in dewatering rate and up to 22% settlement, outperforming conventional incremental loading methods. Significant pH variations induced near electrodes altered clay microstructure: dispersed nature increased the minimum void ratio (e_min) near the 10 V cathode (up to 35%), while flocculated nature near the 30 V anode reduced it by 5% as compared to undisturbed sample. The effect of pH on the shrinkage limit (SL) was evident, as acidification reduced the SL, while it increased under alkaline conditions at each voltage. The air-entry value decreased near cathodes and increased near anodes at each voltage, reflecting voltage-dependent alterations in soil water retention curves at both ends. Additionally, the degradation of Si–O functional groups near the anode (up to 27%) and their enrichment near the cathode (up to 70%) indicate mineralogical reorganization induced by electroosmotic treatment. The preliminary findings from this study encourage exploring electroosmosis to self-consolidate soft sensitive clay in field conditions.