Suction Stress of Soil Slurry

Suction stress, the part of effective stress induced by soil–water interaction, is the source for the intrinsic cohesion of fine-grained soil slurries. Here, the previous unified effective stress equation is generalized to extend the suction stress variation from the liquid state to the oven-dry state, yielding an augmented closed-form equation. This equation includes a new term, named slurry adsorptive suction stress, to incorporate the adsorptive mechanism of soil slurries at the liquid state. This adsorption mechanism involves the interparticle van der Waals attraction, face-to-edge attraction, and electrical double-layer repulsion when soils are in the liquid state. The proposed equation is validated with a wide array of 12 fine-grained soils’ shrinkage curves, modulus, and suction stress data measured by the drying cake test. It is demonstrated that the proposed equation can excellently capture the experimental data across all saturations. Furthermore, the practical implications of the proposed model are illustrated via its relevance to rheological properties of soil slurries and correlations with both liquid limit and plastic limit.