From sedimentation to consolidation of kaolinite: A molecular dynamic study

Abstract

The consolidation of clay is the main measure for reclamation project, which is related to the compressibility, permeability, and coupling effect of clay-water. However, the mechanism of consolidation of clay remains unclear. This study focuses on the microscopic consolidation property of kaolinite using Molecular Dynamics (MD) simulation method. The nano-scale consolidation model was established to reproduce the sedimentation to consolidation. According to the different distribution of water film in pores, the consolidation process could be divided into different stages: (1) in the process of sedimentation and primary consolidation, the drainage occurred continuously except the strongly bound water; (2) just a part of the strongly bound water could be drained during the secondary consolidation. The minimum consolidation stress which can cause significant consolidation was found to be 0.1 GPa in a narrow throat of about 1 nm at nano-scale. The evolution of interparticle spacing between kaolinite particles during the consolidation process was analyzed to reflect the role of interparticle water on the pore water pressure and effective stress. Besides, models with different wettability show that the drainage of water on hydrophilic basal surface was difficult, while water molecules on hydrophobic basal surface are more easily expelled and have directional flow paths.