The Effects of Pore Fluids with Different Dielectric Constants on the Geotechnical Behaviour of Kaolinite

Abstract

The properties of pore fluid in clayey soil are usually influential on the intergranular physicochemical forces, i.e., on the geotechnical properties of clay. In this paper, the Atterberg limits of kaolinite were determined for pure water and four different chemical fluids with various concentrations (20, 40, 60 and 80) whose dielectric constants represent a wide range of interval, and kaolinite’s shear strength and compression behaviors were investigated by using the specimens obtained by consolidating the mixtures under 100 kPa pressure with water content twice their liquid limits. During the tests, an optical microscope was used to take the photographic views of the structural changes taking place on kaolinite due to the changing pore fluids. According to the experimental results, the effect of the chemical fluids caused to have increase in shear strength values and decrease in compression and swelling index values obtained by the consolidation tests. Moreover, kaolinite’s liquid limit increased with the increasing chemical fluid concentration and decreasing dielectric constant of the pore fluid. The changes observed on the geotechnical properties of kaolinite subjected to chemical fluids can be explained with intergranular Van der Waals attraction forces whose increase causes the flocculation of particles and the tendency of the clayey soil to behave like the silt–fine sand. Additionally, the optical microscope views taken during the experiments also supported these conditions clearly.