ABSTRACT
Clay-water interactions and reactions involve, for example, acid-base reactions, oxidation-reduction reactions, and hydrolysis. The interactions and reactions between the clay minerals and water establish the internal energy state of a clay-water system, and affect not only the physical and mechanical properties of clays, but also their hydraulic properties and transport processes in clays. In engineered clay buffers and barriers, the initial water content of the clay is expected to be very low, as engineered clay buffers and barriers are emplaced in a semi-dry to an air-dried state. Interactions between water and clay minerals, and chemical reactions in the porewater and with the clay minerals, will occur first when water is taken into the clay. Various mechanisms and processes are involved in water entry and movement in anhydrous and partly saturated clays. To distinguish ‘what is happening’ at the various stages of water movement in clays, we need to review our perception and understanding of the various terms used to describe water movement, interactions and reactions in clay-water systems.
