The suitability of cement matrices for the long-term immobilisation of radionuclides cannot be predicted from short-term experimental data alone because the chemical properties of cementitious systems change continuously over the repository lifetime. To model such changes is complex, so a stepwise approach has been adopted. A chemically simplified model for the solubility and compositional properties of calcium silicate hydrate gels in the system CaO-SiO//2-H//2O was previously developed but has been extended and improved and is applicable to gels in the wider composition range 0. 8 less than Ca/Si less than 1. 7. The effects of silicate speciation in aqueous solution on the formation of the solid phase have been more fully considered and the dissolution equilibrium has been revised. Solubility products and free energies of C-S-H formation have been evaluated and predictive applications of the model are discussed.
|Title of host publication||Materials Research Society Symposia Proceedings|
|Editors||John K. Bates, Waldemar B. Seefeldt|
|Publisher||Materials Research Soc|
|Number of pages||11|
|Publication status||Published - 1987|