Modeling of leaching in pure cement paste and mortar

Predicting the long-term behavior of concrete, particularly concrete used for radioactive waste disposal, requires a sound knowledge of the various deterioration mechanisms that will affect the structures over their lifetimes and the extensive use of simulation tools. The leaching of cement-based materials is analyzed through experimental and numerical results. From the experimental point of view, the leaching processes of a pure cement paste and a mortar are characterized by the degraded depths and the cumulative amount of leached calcium at different times. From the mathematical point of view, the leaching is modeled with the mass balance equation of calcium in the liquid phase. Material properties useful for a numerical resolution of this equation are presented and the finite volume method is applied for the numerical simulations. Comparisons between experimental and predicted results show the validity of the simple model used to describe the leaching phenomenon and the ability of the finite volume method to support high nonlinearities