Measurement of hydraulic properties of bentonite cake formation deposited on base soil medium

• Hydraulic properties of two different bentonite cakes on base soil medium are estimated under various pressure levels.
• The filtration theory estimates the hydraulic conductivities of bentonite cake ranging from 2.1 × 10− 11 to 5.7 × 10− 10 m/s.
• The 6% of slurry highlights the effect of filter medium on the permeability of the Bentonil GTC4 bentonite cake.
• The thickness and hydraulic conductivity of the filter cake decreases with increasing applied overall pressure.

Bentonite cake and filter cake on the surface of porous media result from the filtration of stabilizing slurry into the adjacent porous formation. This paper provides measurements of hydraulic conductivities of bentonite cake formed on Korean standard sand under various pressure levels. Two types of bentonite (Tixoton and Bentonil GTC4) were used to create the slurries with three different concentrations (4, 6, and 8% by weight). An estimation of the hydraulic conductivity of the bentonite cake based on the filtration theory was carried out. The range of hydraulic conductivities of the bentonite cake was from 2.1 × 10− 11 m/s to 5.7 × 10− 10 m/s. The hydraulic conductivity of the bentonite cake deposited on Korean standard sand were compared with that of the bentonite cake deposited on filter paper to show the effect of the filter medium. The slurry concentration of 6% seems to be a value that most stimulates the effect of the filter medium on the permeability of the Bentonil GTC4 bentonite cake. In addition, a simple approach was developed to characterize the hydraulic properties of the filter cake, which has usually been confused with the bentonite cake in recently published literature.