Pore Morphology, Porosity, and Pore Size Distribution in Kaolinitic Remolded Clays under Triaxial Loading

Abstract This work aims to investigate the micropore properties of saturated kaolin subjected to triaxial loading. Consolidated drained triaxial compression tests were conducted on both normally consolidated and overconsolidated clay specimens. In the (p′, q) plane, a given stress level was reached by following two different stress paths (i.e., the purely deviatoric stress path and the conventional constant σ′3 stress path). This approach allows observing the influence of stress path on the evolution of pore structure. The experimental approach consisted in using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) to quantify the micropore structure of the specimens after being submitted to mechanical loading. The results clearly show that the micropore structure of clay was affected by the loading conditions. Consequently, the development of induced anisotropy appeared as mainly related to the variation of pore shape and pore orientation. Meanwhile, for overconsolidated specimens featuring dilative behavior, the pores exhibited a trend to be more open (i.e., rounder) and more randomly oriented compared with the normally consolidated specimens showing contractive behavior. Even if the micropore structures deduced from the SEM-based method, on the one hand, and from MIP tests, on the other hand, concern different scales of pores, the analysis shows that both methods of investigation were quite well comparable and revealed similar variation tendencies in void ratio and pore size distribution.