Homogenization analysis of surface diffusion in compacted bentonite

Fujii, Naoki; Ichikawa, Yasuaki*

Diffusion in 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 calculation is smaller than the effective diffusion coefficient by experiment. 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 result showed that the total diffusion increase with the increase in a distribution ratio of cation. The increase in the diffusion flux under the increase in a local concentration gradient causes surface diffusion.