Elevated temperature effects on swelling pressure of compacted bentonite

Abstract

Understanding the effects of temperature on the hydro-mechanical behavior of compacted bentonite is important for performance assessments of bentonite-based buffer, backfill, and sealing systems in deep geological disposal of high-level radioactive wastes. Motivated by such applications, most past experimental studies were focused on highly compacted and high-quality bentonite. Such degrees of dry densities may not be economically or technically feasible for other emerging applications, including as an alternative material to cement in plugging and abandonment of wells. A bespoke high-pressure high-temperature constant rate of strain (CRS) apparatus was developed for the work reported here to conduct a series of tests for evaluating the hydro-mechanical response of compacted bentonite to elevated temperatures. Experiments were performed with bentonite specimens with high impurity contents at a range of dry densities (1.1, 1.4, and 1.7 Mg/m³) and temperatures between 20 and 80°C. The results show that temperature increase leads to the decrease of swelling pressure for all studied densities. Larger reductions of swelling pressure were observed with increasing dry densities, suggesting the possibility of a larger exchange of pore water in the microstructure system of the clay. The transfer of water from micropores to macropores at elevated temperatures is shown to be a key controlling process at high-density compacted bentonite by which temperature affects the swelling pressure and hydraulic conductivity.

Keywords

compacted bentonite / nuclear waste / swelling pressure / temperature / well plugging

References

[1] Bag R, Rabbani A. Effect of temperature on swelling pressure and compressibility characteristics of soil. Appl Clay Sci. 2017; 136: 1-7.

[2] Bourg IC, Sposito G, Bourg ACM. Tracer diffusion in compacted water-saturated bentonite. Clays Clay Miner. 2006; 54: 363-374.

[3] Bradbury MH, Baeyens B. Porewater chemistry in compacted re-saturated MX-80 bentonite. J Contam Hydrol. 2003; 61: 329-338.

[4] BS 1377-2. Soils for Civil Engineering Purposes. Part 2: Classification Tests. British Standards Instituition; 1990.

[5] Bucher F, Müller-Vonmoos M. Bentonite as a containment barrier for the disposal of' highly radioactive wastes. Appl Clay Sci. 1989; 4: 157-177.

[6] Cerato A, Lutenegger A. Determination of surface area of fine-grained soils by the ethylene glycol monoethyl ether (EGME) method. Geotech Test J. 2002; 25(3): 315-321.

[7] Chen T, Sedighi M, Jivkov AP, Seetharam SC. A model for hydraulic conductivity of compacted bentonite–inclusion of microstructure effects under confined wetting. Géotechnique. 2021; 71(12): 1071-1084.

[8] Cho WJ, Lee JO, Kang CH. Influence of temperature elevation on the sealing performance of a potential buffer material for a high-level radioactive waste repository. Ann Nucl Energy. 2000; 27: 1271-1284.

[9] Daniels K, Harrington J, Zihms S, Wiseall A. Bentonite permeability at elevated temperature. Geosciences. 2017; 7(1): 3.

[10] ENRESA. FEBEX project. Full-scale Engineered Barriers Experiment for a Deep Geological Repository for High Level Radioactive Waste in Crystalline Host Rock. Final Report. Publicacion Tecnica ENRESA 1/2000, Madrid (354); 2000.

[11] Fernández AM, Baeyens B, Bradbury M, Rivas P. Analysis of the porewater chemical composition of a Spanish compacted bentonite used in an engineered barrier. Phys Chem Earth Parts A/B/C. 2004; 29: 105-118.

[12] Holl HG. Hydraulic testing of compacted bentonite Used for plug and abandonment operations. J Miner Mater Charact Eng. 2019; 7(5): 261-278.

[13] Idemitsu K, Tachi Y, Furuya H, et al. Diffusion of uranium in compacted bentonites in the reducing condition with corrosion products of iron. Mater Res Soc Symp Proc. 1996; 412: 683-690.

[14] Imbert C, Villar MV. Hydro-mechanical response of a bentonite pellets/powder mixture upon infiltration. Appl Clay Sci. 2006; 32: 197-209.

[15] Jacinto AC, Villar MV, Gómez-Espina R, Ledesma A. Adaptation of the van Genuchten expression to the effects of temperature and density for compacted bentonites. Appl Clay Sci. 2009; 42: 575-582.

[16] Jacinto AC, Villar MV, Ledesma A. Influence of water density on the water-retention curve of expansive clays. Géotechnique. 2012; 62(8): 657-667.

[17] Jackson CP, Jefferies NL, Alexander R, et al. Sealing deep site investigation boreholes: Phase 1 report. 2014.

[18] JNC. H12: Project to Establish the Scientific and Technical Basis for HLW Disposal in Japan, Project Overview Report. JNC Technical Report TN1410 2000-001, Japan Nuclear Cycle Development Institute, Tokaimura, Japan; 2000.

[19] Kale RC, Ravi K. Influence of thermal history on swell pressures of compacted bentonite. Process Saf Environ Prot. 2019; 123: 199-205.

[20] Komine H. Simplified evaluation for swelling characteristics of bentonites. Eng Geol. 2004; 71: 265-279.

[21] Komine H, Ogata N. Experimental study on swelling characteristics of compacted bentonite. Can Geotech J. 1994; 31: 478-490.

[22] Lee JO, Lim JG, Kang IM, Kwon S. Swelling pressures of compacted Ca-bentonite. Eng Geol. 2012; 129-130: 20-26.

[23] Lloret A, Villar MV. Advances on the knowledge of the thermo-hydromechanical behaviour of heavily compacted FEBEX bentonite. Phys Chem Earth Parts A/B/C. 2007; 32(8/14): 701-715.

[24] Ma C, Hueckel T. Stress and pore pressure in saturated clay subjected to heat from radioactive waste: a numerical simulation. Can Geotech J. 1992; 29: 1087-1094.

[25] Madsen FT. Clay mineralogical investigations related to nuclear waste disposal. Clay Miner. 1998; 33: 109-129.

[26] Massat L, Cuisinier O, Bihannic I, et al. Swelling pressure development and inter-aggregate porosity evolution upon hydration of a compacted swelling clay. Appl Clay Sci. 2016; 124-125: 197-210.

[27] Mitchell JK, Soga K. Fundamentals of Soil Behaviour3rd edition. John Wiley & Sons, LTD; 2005.

[28] Navarro V, Cabrera V, Merlo O, De la Morena G, Torres-Serra J. Density of water adsorbed on bentonites: determination and effect on microstructural void ratio modelling. Appl Clay Sci2022; 219:106434.

[29] Pusch R. Swelling pressure of highly compacted bentonite. SKBF/KBS technical report: No. 80-13;1980a.

[30] Pusch R. Permeability of highly compacted bentonite. SKB Technical Report 80-16, Swedish Nuclear Fuel and Waste Management; 1980b.

[31] Pusch R. Mineral–water interactions and their influence on the physical behavior of highly compacted Na bentonite. Can Geotech J. 1982; 19: 381-387.

[32] Pusch R, Bluemling P, Johnson L. Performance of strongly compressed MX-80 pellets under repository-like conditions. Appl Clay Sci. 2003; 23(1/4): 239-244.

[33] Pusch R, Karnland O, Hokmark H. GMM a general microstructural model for qualitative and quantitative studies of smectite clays. SKB Technical Report 90–43; 1990.

[34] Pusch R, Ramqvist G. Sealing of 300 mm boreholes KXTT3 and KXTT4 at Äspö HRL. Report of Subproject 3 of Borehole sealing project. No. SKB-R--11-19. Swedish Nuclear Fuel and Waste Management Co; 2011.

[35] Pusch R, Yong RN. Microstructure of Smectite Clays And Engineering Performance. CRC Press; 2006.

[36] Radioactive Waste Managmement Directorate. Sealing Deep Site Investigation Boreholes: Phase 1 Report, vol. I. RWMD/03/042; 2014.

[37] Rautio T Borehole plugging experiment in OL-KR24 at Olkiluoto, Finland., Working report 2006-35, Posiva Oy, Olkiluoto, Finland; 2006

[38] Ruan K, Wang H, Komine H, Ito D. Experimental study for temperature effect on swelling pressures during saturation of bentonites. Soils Found. 2022; 62(6):101245.

[39] Schanz T, Al-Badran Y. Swelling pressure characteristics of compacted Chinese Gaomiaozi bentonite GMZ01. Soils Found. 2014; 54: 748-759.

[40] Schanz T, Tripathy S. Swelling pressure of a divalent-rich bentonite: Diffuse double-layer theory revisited. Water Resour Res. 2009; 45: 1-9.

[41] Sedighi M. An Investigation of Hydro-geochemical Processes in Coupled Thermal, Hydraulic, Chemical and Mechanical Behaviours of Unsaturated Soils. PhD Thesis, Cardiff University; 2011. http://orca.cf.ac.uk/54236/

[42] Sedighi M. Elevated temperature effects on microstructure of compacted smectite International Symposium on Energy Geotechnics, September 25-28, Lausanne, Switzerland; 2018. https://seg2018.epfl.ch/wp-content/uploads/2018/08/EA_152_Sedighi.pdf

[43] Sedighi M, Thomas HR. Micro porosity evolution in compacted swelling clays—a chemical approach. Appl Clay Sci. 2014; 101: 608-618.

[44] Sedighi M, Thomas HR, Vardon PJ. Reactive transport of chemicals in compacted bentonite under nonisothermal water infiltration. J Geotech Geoenviron Eng. 2018; 144(10):04018075.

[45] Tang AM, Cui YJ, Barnel N. Thermo-mechanical behaviour of a compacted swelling clay. Géotechnique. 2008; 58(1): 45-54.

[46] Tiller KG, Smith LH. Limitations of EGME retention to estimate surface area of soils. Aust J Soil Sci. 1990; 28: 1-26.

[47] Towler BF, Firouzi M, Holl HG, et al. Field Trials of Plugging Oil and Gas Wells with Hydrated Bentonite. Proceeding of SPE Asia Pacific Oil & Gas Conference and Exhibition, Perth, 25–27 October 2016.

[48] Tripathy S, Bag R, Thomas HR. Enhanced isothermal effect on swelling pressure of compacted MX80 bentonite. Eng Geol Soc Territory. 2015; 6: 537-539.

[49] Villar MV, Gómez-Espina R, Lloret A. Experimental investigation into temperature effect on hydro-mechanical behaviours of bentonite. J Rock Mech Geotech Eng. 2010; 2: 71-78.

[50] Villar MV, Lloret A. Influence of temperature on the hydro-mechanical behaviour of a compacted bentonite. Appl Clay Sci. 2004; 26: 337-350.

[51] Villar MV, Lloret A. Influence of dry density and water content on the swelling of a compacted bentonite. Appl Clay Sci. 2008; 39(1/2): 38-49.

[52] Ye WM, Wan M, Chen B, et al. Temperature effects on the swelling pressure and saturated hydraulic conductivity of the compacted GMZ01 bentonite. Environ Earth Sci. 2013; 68: 281-288.

RIGHTS & PERMISSIONS

2025 The Author(s). Deep Underground Science and Engineering published by John Wiley & Sons Australia, Ltd on behalf of China University of Mining and Technology.