Zhishin clay and Black Hill bentonite are used as raw clay materials in this study. These clays are mixed with Taitung area hard shale to produce the backfill material for potential application as barrier for the disposal of low-level radioactive waste. The interaction between concrete barrier and the backfill materials is simulated by an accelerated migration test to investigate the effect of concrete on the expected functions of backfill material. The results show some decrease in swelling potential in the backfill material near the interface. Also, backfill material close to the contact with concrete exhibits greater change in the ratio of calcium/sodium concentration, due to the release of calcium ions from the concrete material.