Modeling the Mechanisms of Clay Damage by Molecular Dynamic Simulation

Abstract

We carried out MD simulations to review the mechanisms of clay damage under hydration, the manners clays interact with water and cations, and the structures they form in between aluminosilicate sheets and offered an alternative explanation as to how clay structures become instable after certain water concentration. Water molecules form one, two, and sometimes three layers parallel to the clay surfaces. The cations already present in montmorillonites (the most representative of the smectites) or coming with low salinity water will either be adsorbed by the clay surfaces or become fully hydrated, detached from the surfaces, and located in the midst of the interlayer space between clay surfaces, while water molecules that do not hydrate the cations invade the clay structures, making them unstable. The driving force of this phenomenon happens to be the hydration energy of the cations in question.