Coupling of chemical and hydromechanical properties in bentonite: A new reactive transport model

The reactive transport framework ORCHESTRA was used to implement a dual porosity reactive transport system that accounts for mechanical processes relevant for confined swelling clays at full saturation. The new implementations are based on water retention data generated by molecular dynamics simulations, and on fundamental mechanical formulations. The code predicts and fully couples porewater chemistry, exchanger population, diffusive transport, mineral reactions, volume fractions of the free and Donnan porosity domains, and swelling pressure. The chemomechanical predictions were compared with experimental measurements of swelling pressure and d-value of the clay in different chemical environments. A simulation of bentonite in contact with a constant concentration reservoir demonstrates the performance of the new model approach. It can be used to model interactions of bentonite with different groundwaters or cement and steel.