Hydro-chemio-mechanical coupling effects on permeability and swelling behaviour of a Ca smectite soaked by Cu solutions

Hydro-chemio-mechanical coupling effects in an expansive clay have been studied along soaking paths with oedometer cells equipped with two solute injection systems. Two sets of boundary conditions for soaking were applied: solute and gas–solute mixture. The clay used for the experiments was a Ca French expansive clay known as Fo–Ca. The role of solute chemistry on clay permeability, swelling strain, porosity and on the retention curve was investigated. Copper cations were chosen for taking into account strong adsorption capacity, as the migration of toxic cations normally occurs in acid solutions, exchanges being produced with alkaline content. Permeability as well as swelling strain changes along soaking paths have been investigated with copper concentration with respect to the two sets of boundary conditions. Moreover, the ability of the Fo–Ca for ions sorption was studied by means of leachate analyses. Porosity and retention curves were also given after testing with respect to copper concentrations. Significant changes resulting from the copper solute injection have been obtained for all these material parameters.