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The effects of salt solutions on the properties of bentonite-sand mixtures

  • P. G. Studds (a1), D. I. Stewart (a1) and T. W. Cousens (a1)


The swelling behaviour and hydraulic conductivity of Na-bentonite powder and bentonite-sand mixtures (10 and 20% of bentonite by dry weight) have been measured with distilled water and various salt solutions (0.01, 0.1 and 1 mol/l concentrations), It was found that in dilute solutions, the bentonite in mixtures subjected to small confining stresses swells sufficiently to separate the sand particles and reach a clay void ratio similar to that achieved by bentonite alone. At high stresses, or in strong solutions, the bentonite in a mixture has insufficient swelling capacity to force the sand particles apart and swelling is limited by the sand pore volume. The hydraulic conductivity of a mixture depends on the bentonite void ratio, and the porosity and tortuosity of the sand matrix. A design model is proposed to predict the engineering properties of a mixture over a range of confining stresses from the properties of its constituents and the permeant.


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The effects of salt solutions on the properties of bentonite-sand mixtures

  • P. G. Studds (a1), D. I. Stewart (a1) and T. W. Cousens (a1)


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