Abstract
Diffusion in compacted bentonite clay is investigated by the homogenization analysis, which related the microscale structural and chemical characteristics to the macroscale behavior. However, the diffusion coefficient of the cation by calculations is smaller than the effective diffusion coefficient by experiments. This difference is caused by the surface diffusion. In order to resolve the surface diffusion by numerical analysis, we formulated the phenomenon owing to the cation thickening model on the clay surface by the homogenization technique. The numerical results showed that the total Cs diffusion in compacted bentonite increase with the increase in a distribution ratio of Cs. The increase in the diffusion flux under the increase in a local concentration gradient causes surface diffusion. Although the simulation of the surface diffusion was impossible by the previous homogenization method, this improved method made it possible.
