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

Published online by Cambridge University Press:  09 July 2018

P. G. Studds ,
D. I. Stewart  and
T. W. Cousens
P. G. Studds
Affiliation:
Department of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
D. I. Stewart*
Affiliation:
Department of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
T. W. Cousens
Affiliation:
Department of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
*
*Corresponding author
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Abstract

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.

Type
Research Article
Information
Clay Minerals , Volume 33 , Issue 4 , December 1998 , pp. 651 - 660
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1998

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