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Swelling pressure of a divalent-rich bentonite: Diffuse double-layer theory revisited

Schanz, T. and Tripathy, Snehasis 2009. Swelling pressure of a divalent-rich bentonite: Diffuse double-layer theory revisited. Water Resources Research 45 (5) , W00C12. 10.1029/2007WR006495

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Abstract

[1] Physicochemical forces are responsible for the swelling pressure development in saturated bentonites. In this paper, the swelling pressures of several compacted bentonite specimens for a range of dry density of 1.10–1.73 Mg/m3 were measured experimentally. The clay used was a divalent-rich Ca-Mg-bentonite with 12% exchangeable Na+ ions. The theoretical swelling pressure–dry density relationship for the bentonite was determined from the Gouy-Chapman diffuse double-layer theory. A comparison of experimental and theoretical results showed that the experimental swelling pressures are either smaller or greater than their theoretical counterparts within different dry density ranges. It is shown that for dry density of the clay less than about 1.55 Mg/m3, a possible dissociation of ions from the surface of the clay platelets contributed to the diffuse double-layer repulsion. At higher dry densities, the adsorptive forces due to surface and ion hydration dominated the swelling pressures of the clay. A comparison of the modified diffuse double-layer theory equations proposed in the literature to determine the swelling pressures of compacted bentonites and the experimental results for the clay in this study showed that the agreement between the calculated and experimental swelling pressure results is very good for dry densities less than 1.55 Mg/m3, whereas at higher dry densities the use of the equations was found to be limited.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Engineering
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Uncontrolled Keywords: Clays; expansive clays; bentonite
Additional Information: Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0043-1397/ (accessed 28/08/2014)
Publisher: American Geophysical Union
ISSN: 0043-1397
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 01:53
URI: http://orca.cf.ac.uk/id/eprint/5466

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