The engineering or sealing materials is an integral part of a repository design system for the disposal by isolation of nuclear wastes in geologic media. Cement, concrete, zeolites and clay minerals are some of the promising candidate borehole plugging or sealing materials. In order to evaluate the efficacy of these sealing materials, Cs+ and Cl- diffusion studies were conducted on thin cured discs or cement and cement admixtures with zeolite or montmorillonite or silica fume or blast furnace slag. The cement admixtures are superior to straight cement in retarding the migration of Cs+ and Cl-. The montmorillonite blended cement performs in an intermediate fashion when compared to the straight cement and zeolite or silica fume bearing cements. The diffusions of Cs+ and Cl- appear to be related to the pore structure as well as the crystal structures of the phases added or subsequently formed during curing. These results tend to suggest that the addition of 10-20% silica fume or zeolite phase to the portland cement may be very advantageous in resisting the migration of Cs+ and, to some extent, Cl- ions across cement pastes.
All Science Journal Classification (ASJC) codes
- Building and Construction
- Materials Science(all)