抄録
Long term behavior of a bentonite sand mixture used for the disposal of radioactive wastes has been of great concern when it continuously contacts with concrete. This is explained by the fact that the characteristics of the bentonite will be altered due to the leaching of calcium ions in the concrete. In particular the Sodium type (Na type) bentonite exhibits a reduced expansion characteristic. However little research has been conducted using a bentonite-concrete composite system to investigate long term effects.
In this present research an alteration of the characteristics of the Na type bentonite is studied by the use of a concrete bentonite composite specimen. An electrical migration method was employed to accelerate the transport of calcium ions present in the pore solution in concrete through the interface of a bentonite sand mixture. A constant DC voltage of 15 V was continuously applied to a concrete bentonite composite specimen for 50 days. Chemical analysis for cation content and expansion force, the measurements of EPMA and XRD were conducted.
