DISCUSSION ON WATER MIGRATION AND SWELLING OF COMPACTED POWDER BENTONITES

Abstract

 Bentonite based buffer will change its condition from unsaturated state to saturation by groundwater seepage in high level radioactive waste disposal facility. This study has investigated water migration and swelling pressure characteristics in bentonite based buffer from unsaturated state to saturation from the viewpoint of material specifications such as kinds of bentonite and dry density. From the experimental results in this study, water migration behaviors in various powder bentonites as buffer have an analogy to water-diffusion from initial water content to around 90% saturation. Furthermore, the inflection points have appeared at around 90% saturation in the relationships between swelling-pressure and elapsed time. Therefore, the factor dominating water migration in buffer will change according to alternation of micro-structure in bentonite based buffers by swelling.