A model has been developed for prediction of pore water chemistries and solid constituents of cement, in order to study the cement degradation process caused by dissolution of hydrates. The dissolution models of portlandite, hydrated calcium-silicate gels and other hydrates, which are the main hydrates in cement, are introduced into the geochemical code to couple with the one-dimensional advective-dispersion transport model. The pH and the chemical concentrations in pore water, and the distributions of pore volume and elements in solid are studied by using this coupled code. The calculated results agree with the permeability test results for hardened cement. By using calculated results of distributions of elements, hydrates and pore volume in solid, the dissolution process in which the hydrated cement is altered by its own dissolution is discussed.
