Swelling Pressure and Permeability of Compacted Bentonite from 10th Khutor Deposit (Russia)

Abstract

Bentonites from the 10th Khutor deposit (Republic of Khakassia, Russia) are considered a potential buffer material for isolation of radioactive waste in the crystalline rocks of Yeniseyskiy site (Krasnoyarskiy region). This study presents the results of a series of permeameter experiments with bentonite compacted to dry densities of 1.4, 1.6, and 1.8 g/cm3, saturated and permeated by the artificial groundwater from Yeniseyskiy Site. Permeation was conducted at hydraulic gradients of 180–80,000 m/m to simulate potential hydraulic conditions in the early post-closure phase of a deep geological repository (DGR). The respective swelling pressures of 0.8 ± 0.3, 2.2 ± 0.6, and 6.3 ± 0.3 MPa and permeabilities of (27 ± 15) × 10−20, (3.4 ± 0.8) × 10−20, and (0.96 ± 0.26) × 10−20 m2 were observed for the hydraulic gradient of 2000 m/m, which is recommended for the determination of undisturbed swelling pressures and permeabilities in permeameter experiments. Upon incremental increases in the hydraulic gradient, swelling pressures at all densities and permeability at the density of 1.8 g/cm3 remained unchanged, whereas permeabilities at 1.4 and 1.6 g/cm3 decreased overall by a factor of approximately 5 and 1.7, respectively. Seepage-induced consolidation and/or reorganisation of bentonite microstructure are considered possible reasons for these decreases.

Mineralogical and Physico-Chemical Characterization of the Oraşu-Nou (Romania) Bentonite Resources

“…tonites from the Oraşul Nou deposit can be considered a potential buffer material for isolation of radioactive waste, where they can be used due to their low permeability and high CEC [34]. Bentonite blocks serve as a sealing material around waste canisters to isolate them from the surrounding atmosphere [35].…”

“…They can also be used in pollutant removal processes for industrial or civilian residual waters [29,30], for the purification of industrial gases, protection of waste storage areas [31], including nuclear waste storages [32,33]. Bentonites from the Oraşul Nou deposit can be considered a potential buffer material for isolation of radioactive waste, where they can be used due to their low permeability and high CEC [34].…”

A MiniSandwich Experiment with Blended Ca-Bentonite and Pearson Water—Hydration, Swelling, Solute Transport and Cation Exchange

“…These paths slowly closed and the permeability decreased again. The second and third increase of the permeability might have been similarly caused by local changes in the discrete fluid pathways due to the more pronounced swelling of the bentonite granules in cell 9 and a rearrangement of the inter-aggregate pores in the DS as described for pure bentonites in Meleshyn, et al [23].…”

Characteristics and Rates of Microbial Processes in Clays of Different Mineral and Elemental Composition in Relation to Safety Prediction for ESB Clay Materials

“…Clays and clay materials are used for deep disposal of the waste of nuclear power plants in the USA, France, Sweden, etc. [3][4][5][6]; it is also planned in Russia [7,8].…”