Pore-size changes and responses of kaolinite with different structures subject to consolidation and shearing

• Consolidation and shearing involves the inter-aggregate pores of kaolinites.
• Mechanical responses of kaolinite depend on aggregate-to-aggregate interactions.
• The aggregates of kaolinite can be considered analogous to sand particles.

In this paper, the responses of kaolinite samples with two different soil structures, i.e., unwashed and pH 7.8 samples, under 1-D consolidation, isotropic loading–unloading and triaxial shearing are examined. The focus is on the associated changes in the pore-size distribution. During isotropic consolidation, the unwashed sample, with an open, aggregated and flocculated structure, exhibits higher compressibility than the pH 7.8 sample, which has a densely packed aggregated structure. The associated deformation in both samples primarily arises from the compression of the large inter-aggregate pores, which are not controlled by the suppression of the electrical double layer, and the intra-aggregate pores remain almost unchanged during consolidation. Similar behavior is observed in clay samples with different structures during 1-D consolidation and triaxial shearing that only the inter-aggregate pores are affected and the intra-aggregate pores stay almost the same. All of these findings suggest that the mechanical responses of kaolinite clay depend on aggregate-to-aggregate interactions rather than on particle-to-particle interactions. The aggregates of kaolinite clay can be considered analogous to sand particles.