Long-term modeling of glass waste in portland cement- and clay-based matrices

Abstract

A set of "templates" was developed for modeling waste glass interactions with cementbased and clay-based matrices. The templates consist of a modified thermodynamic database, and input files for the EQ3/6 reaction path code, containing embedded rate models and compositions for waste glass, cement, and several pozzolanic materials. Significant modifications were made in the thermodynamic data for Th, Pb, Ra, Ba, cement phases, and aqueous silica species. It was found that the cement-containing matrices could increase glass corrosion rates by several orders of magnitude (over matrixless or clay matrix systems), but they also offered the lowest overall solubility for Pb, Ra, Th and U. Addition of pozzolans to cement decreased calculated glass corrosion rates by up to a factor of 30. It is shown that with current modeling capabilities, the "affinity effect" cannot be trusted to passivate glass if nuclei are available for precipitation of secondary phases that reduce silica activity. 4.1 THERMODYNAMIC DATA 10