CLASSIFICATION OF BOUND WATER FORMS IN KAOLINITIC CLAYS

Abstract

Relevance. Water is the most important component of soils, as it influences the main geological processes. This is due to the peculiarities of its composition and structure. Many scientists have studied the issue of the content of bound water in clays. However, experiments on this issue are not enough. The purpose of this work is to study the forms of bound water in kaolinite clays squeezed out at high pressures, as well as to reveal the relationship between the loss of water masses under pressure and thermodynamic parameters. The object of the research is kaolinite clays. Method. To achieve this goal, samples were prepared with various degrees of compression under pressure, and then thermogravimetric and diffractometric analyzes were performed. The results of experimental data and analysis of thermograms made it possible to identify four peaks of water mass loss, in accordance with this, a classification of bound water in clay was proposed: loosely bound water on the surface of colloids; firmly bound water on the surface of colloids; mineral surface water; crystal lattice water. The impact of high pressure on the mass of removed water is ambiguous. This is due to the fact that the formation of defects occurs under pressure, as a result, the energy potential and sorption activity of clay particles change. At the same time, a close relationship was revealed between the roughness index and the gradient of the removed bound water in the pressure range from 0 to 200 MPa. Relationship is not established at pressures from 200 to 800 MPa.

Keywords

• kaolinite clay
• forms of bound water
• thermogravimetry
• pressure
• specific surface area
• roughness
• sorption activity