ABSTRACT
Gaomiaozi (GMZ01) bentonite, which originated from a deposit locates in Xinghe County, Inner Mongolia Autonomous Region, China, has been considered as the first choice for using as buffer/ backfill materials for deep disposal of high radioactive waste in China. For this purpose, densely compacted GMZ01 bentonite should present satisfactory thermal stability. In this paper, laboratory tests were conducted to obtain hydro-thermal behaviour of densely-compacted GMZ01 and its water retention properties were determined under both confined and unconfined conditions at temperature: 20, 40, 60 and 80°C. The vapour equilibrium technique was employed for suction control. Results show that, i) the water retention capacity of the highly compacted bentonite under confined/unconfined conditions falls with heating; ii) for high suction (greater than 4 MPa), no difference was observed between the water retention curves of confined and unconfined specimen, while for low suction, the water-retention capacity of confined sample was found to be significantly lower than that of unconfined sample at same temperature; iii) the hysteresis of the unconfined compacted bentonite decreases as temperature increases; for high suctions (greater than 4 MPa), there is an increasing trend in hysteresis of unconfined bentonite when suction decreases.
