Abstract：Attentions have been devoted in recent years to the behaviors of highly compacted bentonites used in engineered barriers for high level radioactive nuclear waste disposal. Througth a nationwide screening and comparison，Gaomiaozi(GMZ) bentonite deposit located in Xinghe County，Inner Mongolia，is considered as the first choice of Chinese buffer materials for high-level radioactive waste geological repository. A laboratory study has been carried out on compacted GMZ bentonite，including the measurement of soil-water characteristic curves(SWCC)，the environmental scanning electron microscopy(ESEM) test，and the mercury intrusion porosimetry(MIP) test. The osmotic technique and vapour equilibrium technique were used for controlling suction. Comparison between the SWCCs of GMZ bentonite obtained from the MIP test results and the measured data under confined conditions is also made. Water retention properties of the GMZ bentonites under different suctions are related closely with to microscopic mechanisms.
