Compressive behavior of kaolinitic clay under chemo-mechanical loadings

A series of laboratory experiments, including sedimentation, liquid limit, SEM and oedometer tests, was performed to explore the influence of chemo-mechanical loadings on the compression behavior of kaolinitic clay. The results indicate that the concentration and valence of pore solution have significant effect on the volume change of kaolinitic clay. The volume change can be attributed to the change of intergranular forces caused by the variation of pore water chemistry. It is observed that the recompression curves under mechanical loading after solution replacement at various vertical stresses merge into a single curve. In addition, the salinization-induced volumetric strain under the same vertical stress is independent of the step number of salinization, provided that the total change of ionic strength is the same. A recently developed formulation of intergranular stresses, which accounts for the physicochemical interactions between the solid matrix and the pore solution, is introduced to interpret the experimental results. It is shown that the compression behaviors of kaolinitic clay under complex chemical and mechanical loadings can be remarkably unified by a single intergranular stress, showing the capability of the intergranular stress in describing the chemo-mechanical behavior of kaolinitic clay.