CHANGES IN ADHESION FORCES OF MONTMORILLONITE AND KAOLIN CLAYS AT STRESS PRESSURES

Abstract

For the formation of the technological properties of clays, various methods of their processing have been developed: thermal, chemical, ultraviolet, mechanical, etc. However, the issues of changing the energy properties of the surface of clay particles, previously compacted by stress pressure, are not fully understood. Therefore, the aim of the work is to study the patterns of change in adhesion forces on the surface of particles of montmorillonite and kaolin clays treated with stress pressure up to 800 MPa and a shift of 90°. The adhesion forces of clay samples subjected to stress pressure and shear were studied using an NT-MDT NTEGRA Prima atomic force microscope (Russia). It was experimentally proved that during the machining of kaolin and montmorillonite clays by stress pressure and shear changes in adhesion forces are multidirectional in nature. In kaolin clay, as the pressure increases, the adhesion force increases. In montmorillonite, an increase in pressure up to 150 MPa leads to an increase in the adhesive interaction, a further increase to 800 MPa leads to its decrease. It was revealed that during the processing of clays by stress pressure and shear, the processes of crushing, aggregation and deformation of particles occur in them, leading to a change in the defectiveness of the crystal lattice and the surface of the particles. Such transformations create changes in the energy potential of clay particles, which in turn changes the sorption and adhesive properties of clays. At the same time, in the studied soils the formation of the energy potential on the surface of particles takes place in different ways: in kaolin clays, the main factor is the crushing process, and in montmorillonite — aggregation.