EVALUATING INFLUENCE OF CEMENTATION ON SWELLING PROPERTIES OF BENTONITE BUFFER MATERIAL BASED ON THE RESULTS OF BENTONITE ORES

In the high-level radioactive waste geological disposal, bentonite buffer material will be keeping exposed to complex environmental of high pressure and high temperature. Therefore, bentonite buffer material will be consolidated and its physical properties such as swelling and permeability will be changed. In this study, the authors thought that bentonite raw ore, consolidated in the natural ground, will have similar properties of consolidated buffer material. Three sodium type bentonite ore were choosen whose mined places and age were different. For experimental evaluation of influence of cementation on swelling properties, the authors made undisturbed and reconstituted specimens, and conducted swelling pressure and one-dimen-sional swelling deformation tests. As a result, for the undisturbed specimens, it was tended to have lower swelling properties than the reconstituted specimens by the effect of cementation. Also, the swelling properties tended to decline as the geological age of the ores was older.