THE DEVELOPMENT OF DURABLE CEMENTITIOUS MATERIALS FOR USE IN A NUCLEAR FUEL WASTE DISPOSAL FACILITY

This paper describes the work on cement paste development and short-term leaching tests in Standard Canadian Shield Saline Solution (SCSSS) in the presence of bentonite at 150 °C. The objective was to evaluate the performance of various cementing materials in enhancing the properties of sulphate resistant portland cement (SRPC). Methodologically, the study involved the addition of supplementary cementing materials, including silica fume and fly ash, and the incorporation of bentonite in the testing process. Results showed that these supplementary materials could significantly improve the permeability to water and pore size distribution of SRPC. Furthermore, the addition of bentonite was found to suppress the rapid increase of groundwater pH experienced in conventional cement mixtures. It was also observed that the presence of bentonite enhanced the release of potassium ions from the cements. Notably, SRPC blended with 20% silica fume exhibited a lower groundwater pH compared to SRPC alone, with the cumulative fraction of released potassium being significantly lower than that of SRPC, both with and without bentonite. The findings indicate the potential for improved cement formulations for use in nuclear waste containment applications.