The evolution of clay rock/cement interfaces in a cementitious repository for low- and intermediate level radioactive waste

► We compared geochemical evolution at host rock/concrete interfaces. ► We developed a set of thermodynamic data, valid for different materials. ► The thermodynamic model contains intrinsically varying cation exchange properties. ► The mineralogical changes at material interfaces are restricted to narrow zones. ► The calculations show massive porosity changes near the interface.