Advertisement

Thermal Water Retention Characteristics of Compacted Bentonite

Conference paper

Abstract

Compacted bentonites are popularly being considered as buffer or backfill material in high level nuclear waste repositories around the world. These bentonites may undergo various conditions including hydration from around geo-environmental water and heating by the radiation of the used fuel during its period of operation. Water retention properties of as-compacted Czech bentonite B75 with three initial dry densities (1.27 g/cm3, 1.60 g/cm3 and 1.90 g/cm3) and bentonite powders were investigated within temperature 20–80 °C at unconfined conditions. Vapor equilibrium method was used to control constant relative humidity. The influence of temperature on water retention properties was analyzed and discussed. Results show that the temperature decreased water retention capacity for all cases. The water retention capacity is lower at high temperature especially at lower suction. The temperature has more significant effect on drying path than wetting path. Furthermore, the volume swelling decreased with the increased temperature upon saturation. The hysteretic behavior decreased with the increase of temperature for all studied materials.

Keywords

Bentonite Temperature Water retention capacity 

Notes

Acknowledgements

Financial support by the research grant GACR 15-05935S of the Czech Science Foundation is greatly appreciated. This project receives funding from the Euratom research and training programme 2014–2018 under grant agreement No 745942. The first author acknowledges support by the grant No. 846216 of the Charles University Grant Agency. The authors are grateful to the Centre of Experimental Geotechnics of Czech Technical University (prof. J. Pacovský, Dr. J. Svoboda, Dr. R. Vašíček) for providing access to their thermal facilities.

References

  1. 1.
    Grant, S.A., Salehzadeh, A.: Calculation of temperature effects on wetting coefficients of porous solids and their capillary pressure functions. Water Resour. Res. 32(2), 261–270 (1996)CrossRefGoogle Scholar
  2. 2.
    Romero, E., Gens, A., Lloret, A.: Suction effects on a compacted clay under non-isothermal conditions. Géotechnique 53(1), 65–81 (2003)CrossRefGoogle Scholar
  3. 3.
    Yao, Y.P., Zhou, A.N.: Non-isothermal unified hardening model: a thermo-elasto-plastic model for clays. Geotechnique 63(15), 1328 (2013)CrossRefGoogle Scholar
  4. 4.
    Zhou, A.N., Sheng, D., Li, J.: Modelling water retention and volume change behaviours of unsaturated soils in non-isothermal conditions. Comput. Geotech. 55, 1–13 (2014)CrossRefGoogle Scholar
  5. 5.
    François, B., Laloui, L.: ACMEG-TS: a constitutive model for unsaturated soils under non-isothermal conditions. Inte. J. Numer. Anal. Meth. Geomech. 32(16), 1955–1988 (2008)CrossRefGoogle Scholar
  6. 6.
    Mašín, D.: Coupled thermo hydro mechanical double-structure model for expansive soils. J. Eng. Mech. 143(9), 04017067 (2017)CrossRefGoogle Scholar
  7. 7.
    Sun, H., Mašín, D., Boháč, J.: Experimental characterization of retention properties and microstructure of the Czech bentonite B75. In: Proceedings of the 19th International Conference on Soil Mechanics and Geotechnical Engineering, Seoul, pp. 1249–1252 (2017)Google Scholar
  8. 8.
    Delage, P., Howat, M.D., Cui, Y.J.: The relationship between suction and swelling properties in a heavily compacted unsaturated clay. Eng. Geol. 50, 31–48 (1998)CrossRefGoogle Scholar
  9. 9.
    Greenspan, L.: Humidity fixed points of binary saturated aqueous solutions. J. Res. Natl. Bur. Stan. 81(1), 89–96 (1977)CrossRefGoogle Scholar
  10. 10.
    The International Organization of Legal Metrology (OIML): The scale of relative humidity (RH) of air certified against saturated salt solutions. OIMLR 121, France (1996)Google Scholar
  11. 11.
    Tang, A.M., Cui, Y.J.: Controlling suction by the vapour equilibrium technique at different temperatures and its application in determining the water retention properties of MX80 clay. Can. Geotech. J. 42(1), 287–296 (2005)CrossRefGoogle Scholar
  12. 12.
    Sun, H., Mašín, D., Najser, J., Neděla, V.: Bentonite micro-structure evolution in wetting-drying cycles studied by ESEM, MIP and WRC measurements, Géotechnique, (under view) (2018)Google Scholar
  13. 13.
    Nelson, J.D., et al.: Foundation Engineering for Expansive Soils (2015). ISBN: 978-0-470-58152-0Google Scholar
  14. 14.
    Villar, M.V., Lloret, A.: Influence of temperature on the hydro-mechanical behaviour of a compacted bentonite. Appl. Clay Sci. 26(1), 337–350 (2004)CrossRefGoogle Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Faculty of Science, Institute of Hydrogeology, Engineering Geology and Applied GeophysicsCharles UniversityPragueCzech Republic

Personalised recommendations