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The factors controlling the engineering properties of bentonite-enhanced sand

Stewart, D.I., Studds, P.G. and Cousens, T.W. (2003) The factors controlling the engineering properties of bentonite-enhanced sand. Applied Clay Science, 23 (1-4). 97-110. ISSN 0169-1317

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This paper considers the engineering behaviour of bentonite-enhanced sand (BES) mixtures in relation to their performance as environmental barriers. Data on the swelling and hydraulic conductivity are presented. At low effective stresses the bentonite within BES mixtures swells sufficiently to separate the sand particles. In such states two factors affect the void ratio reached by the bentonite after swelling: the ionic concentration of the pore solution and the bentonite fabric after compaction. Bentonite swelling is very sensitive to the pore solution concentration because increasing concentration suppresses the diffuse double layer component of swelling. Remoulding during compaction can result in a slight reduction in bentonite swelling, probably because of disruption to the cluster-based fabric of bentonite. At high effective stresses the bentonite has insufficient swelling capacity to force the sand particles apart, and the sand pore volume thus limits swelling.

A model to predict the swelling and hydraulic conductivity of BES in distilled water and various salt solutions is described. This model requires the swelling behaviour and hydraulic conductivity of the bentonite in the relevant solution, and the compressibility and porosity of the sand component as input parameters. Soil tortuosity is used as a fitting parameter, and is estimated from Archie’s equation. Application of this model to the swelling of compacted mixtures is shown to produce a good fit with the experimental data.

Item Type: Article
Copyright, Publisher and Additional Information: © 2003 Elsevier Science B.V. All rights reserved. This is an author produced version of a paper published in Applied Clay Science.
Keywords: Barriers; Bentonite; Geotechnical engineering; Hydraulic conductivity; Landfill; Sand
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Engineering (Leeds) > School of Civil Engineering (Leeds)
The University of Leeds > Faculty of Engineering (Leeds) > School of Civil Engineering (Leeds) > Inst for Pathogen Control Engineering (Leeds)
Depositing User: Douglas I Stewart
Date Deposited: 21 Jun 2006
Last Modified: 04 Jun 2014 12:21
Published Version: http://dx.doi.org/10.1016/S0169-1317(03)00092-9
Status: Published
Publisher: Elsevier
Refereed: Yes
Identification Number: 10.1016/S0169-1317(03)00092-9
Related URLs:
URI: http://eprints.whiterose.ac.uk/id/eprint/1329

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