Microstructural transformations of swelling clay minerals

Abstract

An original model of microstructural transformations during clay swelling is considered, a thermodynamic and physical-mechanical description of the properties of clays during the process of swelling in vapors and aqueous solutions is given. The model proposed to explain these properties is based on the concept of mutual displacement of clay particles in clay rock aggregates during swelling with the formation of new pores between clay particles forming crystallites and aggregates. The model is based on the mechanism of utilization of the excess surface energy of clay particles during hydration, taking into account the influence of certain environmental parameters, for example, the concentration of the solution, through a change in the mutual orientation of clay particles, mainly due to rotations or shifts relative to each other, with the formation of an area available for further wetting free surface. In the thermodynamic description, such a process will manifest itself in a change in the surface interaction energy on the wetted areas of the particles when moving during mutual shifts and rotations. At the same time, one of the most important parameters of clay rock, microporosity, also changes. In this work, this phenomenon was experimentally studied using the methods of static moisture capacity and Mössbauer (NGR) spectroscopy. The proposed model makes it possible to explain the features of the clay hydration process and to compare the observed experimental data with the theoretical description of the clay swelling process.