Influence of sodium-rich water on the hydraulic conductivity of a model soil-bentonite backfill
Influence of sodium-rich water on the hydraulic conductivity of a model soil-bentonite backfill
The purpose of this study was to investigate the influence of sodium-rich water on the hydraulic conductivity of a model soil-bentonite cutoff wall backfill containing uniform sand and sodium bentonite. Four backfill samples were created by combining the sand with bentonite slurry and additional dry bentonite to achieve a total bentonite content of 5 % by dry mass. Each sample was prepared using mix water with a different NaCl concentration, CM, ranging from 10 to 500 mM. Backfill specimens were permeated in flexible-wall cells under a low effective confining stress (14 kPa) using permeant liquids with NaCl concentrations, CP, ranging from 10 to 1,000 mM. Final hydraulic conductivities (kf) for specimens prepared with a given mix water generally increased with increasing CP, but the increases were modest (i.e., 1.2x to 2.6x). Increases in CM had a greater impact on kf relative to CP, causing up to a two-fold increase in kf for CM = 50 mM, a four- to six-fold increase in kf for CM = 100 mM, and a 10- to 55-fold increase in kf for CM = 250-500 mM relative to the backfill mixed with CM = 10 mM. The results illustrate the importance of mix water quality as the dominant factor controlling the initial bentonite fabric and, therefore, the hydraulic conductivity of the backfill.
Michael Malusis; S. Jacob; D. Ruffing
9th International Congress on Environmental Geotechnics (ICEG2023)
Engineered Barriers
Groundwater & Seepage, Geoenvironmental Engineering
https://doi.org/10.53243/ICEG2023-8
Contact Information
- Secretary General - Dr A M McNamara
- Email: [email protected]
- Phone: +44 20 7040 8154
- City, University of London
- Northampton Square
- London EC1V 0HB. United Kingdom