The objective of this study is to investigate the fabric effects on the mechanical responses of kaolinite and its pore-size evolution at different stress states. Samples with two distinct fabric associations, i.e., flocculated and dispersed structures, are investigated. The results of sedimentation tests and mercury intrusion porosimetry (MIP) tests suggest that the sample with flocculated structure, i.e., the unwashed and pH 7.8 with salt samples, exhibit an open packing and the feature of dual porosity. The sample with dispersed structure, i.e., the pH 7.8 sample, possesses a dense packing. _c...[ Read more ]

The objective of this study is to investigate the fabric effects on the mechanical responses of kaolinite and its pore-size evolution at different stress states. Samples with two distinct fabric associations, i.e., flocculated and dispersed structures, are investigated. The results of sedimentation tests and mercury intrusion porosimetry (MIP) tests suggest that the sample with flocculated structure, i.e., the unwashed and pH 7.8 with salt samples, exhibit an open packing and the feature of dual porosity. The sample with dispersed structure, i.e., the pH 7.8 sample, possesses a dense packing.

Under isotropic and one-dimensional consolidation, the sample with flocculated structure has a greater compression index, C_c, compared with the sample with dispersed structure. However, both samples have similar recompression indices, C_r. In addition, the sample with flocculated structure possesses a larger axial strain than the radial strain during isotropic consolidation while the sample with dispersed structure shows an opposite trend. During isotropic unloading, both samples show a higher elastic rebound in the axial direction, which is due to the contribution from the regain of the double layer thickness. In the one-dimensional consolidation, the secondary compression index, C_α, of the sample with flocculated structure is greater than the sample with dispersed structure but the values follow the same trend of C_c. This supports the observation that the secondary consolidation is a continuous process of the primary consolidation.

From the MIP results, the intra-aggregate pores are found to be almost unchanged after triaxial shearing to large strains. All the shearing deformation is attributed to the redistribution of inter-aggregate pores and the reorientation aggregates. There is no sign of rupturing of aggregates. In samples after oven-dried, both the inter-aggregate and intra-aggregate pores are affected, which suggests that the oven drying process can further pull the particles to get closer.