ABSTRACT
Figure 1 presents a schema of an engineered barrier (EB) section of a disposal pit according to the concept of deep nuclear waste disposal. One can appreciate the EB surrounding the waste container (C) and filling up the void zone between the pit walls crossed in the host rock (HR) and the container. The EB is composed of specially shaped compacted bentonite bricks arranged in such a way that void zones (joints) are minimized. The joints are present in the EB-EB, EB-C and EB-RH contact surfaces and their presence within the barrier highlight the importance of the swelling potential of the EB material. The self sealing capacity of bentonites is particularly important to ensure an adequate isolation of the waste (Pusch 1982). Marcial et al. (2006) have shown with a reduced model test, that in bentonite based EB, such joint system could heal very soon with hydration if the joint sizes are small enough, even for a relatively low EB dry density. However, higher periods of time could be necessary as the joint size increases.
