A Thermoanalytic Quantitative Method for Studying the Bound Water of Sodium Montmorillonite

In hydration process, water molecules adsorbed by clay particles in different hydration stages have different structures and properties. The adsorbed water includes free water and bound water, which have different ways of being attached onto clay particles. Researchers both at home and abroad have paid more attention to qualitative analysis of the type and amount of the bound water, the quantitative analysis of bound water and research on the effects of the type and amount of bound water on rock mechanics, on the other hand, provides a quantitative correction method for the establishment of force-chemistry coupling model. Assume that the sodium montmorillonite particles are in a shape of hexahedron, a power function model describing the relationship between the amount of bound water and the total adsorbed water of sodium montmorillonite can be established taking into account the micro characteristics of water adsorption. The type and amount of water adsorbed by sodium montmorillonite can be measured with thermogravimetry, airdrying of clay, adsorption in room temperature and isotherm adsorption. The experimental data are then fitted with data from model calculation. The results show that the product of the relative errors and the geometric mean of relative errors of the established model are both approximately equal to 1, indicating that the established model has good precision of prediction.