ABSTRACT
One of the characteristic properties of argillaceous soils is their multiphase state. The specific features of each phase in isolation and its physico-chemical and mechanical properties determine the overall properties of the soil which include expansion (increase of volume with addition of moisture) and contraction (decrease of volume with reduction of moisture). The clay fraction plays an essential role during the interaction between soil and water. A combination of individual particles and aggregates leads to the formation of a structural system. The particles lying at the surface and the exchangeable cations participate in the processes occurring at the dividing line between the two phases and dictate the extent of attraction of water molecules. The concentration of salts in the pore fluid affects swelling. The gradient arising out of the difference in the concentration of salts in the pore fluid and the wetting agent leads to an osmotic accumulation of water in the interspace between particles.
