Temperature effects on soil-water retention properties of densely compacted GMZ01 bentonite
Résumé
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 con- ducted to obtain hydro-thermal behaviour of densely-compacted GMZ01 and its water retention proper- ties 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 reten- tion 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.