Hostname: page-component-78c5997874-mlc7c Total loading time: 0 Render date: 2024-11-07T23:10:34.506Z Has data issue: false hasContentIssue false
  • English
  • Français

Micro-Structure and Hydraulic Conductivity of Simulated Sand-Bentonite Mixtures

Published online by Cambridge University Press:  01 January 2024

Tarek Abichou ,
Craig H. Benson  and
Tuncer B. Edil
Tarek Abichou*
Affiliation:
Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310, USA
Craig H. Benson
Affiliation:
Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
Tuncer B. Edil
Affiliation:
Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
*
*E-mail address of corresponding author: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

This paper describes the relationship between the micro-structure and hydraulic conductivity of simulated sand-bentonite mixtures (SSBMs) prepared with powdered and granular bentonite. Glass beads were used to simulate sand grains because of their superior optical properties. The micro-structure of SSBMs was observed using optical micrography and scanning electron microscopy. For mixtures prepared with powdered bentonite, the indications are that bentonite coats the particles. As the bentonite content increases, the thickness of bentonite coating increases and reduces the area available for flow. For mixtures containing granular bentonite, the dry bentonite granules occupy the space between the particles and then swell to fill the void space. As the bentonite content increases, the number of granules increases, leading to more void spaces being filled with bentonite. At higher bentonite content (>8%), flow paths devoid of bentonite are unlikely, and the hydraulic conductivity appears to be controlled by the hydraulic conductivity of bentonite. The changes in micro-structure that were observed are consistent with the decrease in hydraulic conductivity that occurs with increasing bentonite content. However, the relationship between hydraulic conductivity and bentonite content differs depending on whether a mixture contains powdered or granular bentonite.

Keywords

Bentonite DistributionHydraulic BarrierHydraulic ConductivityMicro-structureSand-Bentonite MixturesOptical MicrographsScanning Electron Micrographs
Type
Research Article
Information
Clays and Clay Minerals , Volume 50 , Issue 5 , October 2002 , pp. 537 - 545
Copyright
Copyright © 2002, The Clay Minerals Society

References

Abichou, T., (1999) Hydraulic properties of foundry sands and their use as hydraulic barriers Wisconsin, USA University of Wisconsin-Madison.Google Scholar
Boley, T. and Overcamp, T., (1998) Displacement of nonwetting liquids from unsaturated sands by water infiltration Groundwater 36 810–814 10.1111/j.1745-6584.1998.tb02199.x.Google Scholar
Chang, M. Trussell, R. Guzman, V. Martinez, J. and Delaney, C., (1999) Laboratory studies on clean bed headloss of filter media Aqua 48 137 145.Google Scholar
Chapuis, R., (1990) Simulated sand-bentonite liners: predicting permeability from laboratory tests Canadian Geotechnical Journal 27 47–57 10.1139/t90-005.Google Scholar
Gnanapragasm, N. Lewis, B. and Finno, R., (1995) Microstructural Changes in Simulated Sand-Bentonite Soils When Exposed to Aniline Journal of Geotechnical Engineering 121 119–125 10.1061/(ASCE)0733-9410(1995)121:2(119).Google Scholar
Graham, J. Saadat, F. Gray, M. Dixon, D. and Zhang, Q., (1989) Strength and volume change behavior of a simulated sand-bentonite mixture Canadian Geotechnical Journal 26 292–305 10.1139/t89-038.Google Scholar
Hozalski, R. and Bouwer, E., (1998) Deposition and retention of bacteria in backwashed filters American Water Works Association 90 71–85 10.1002/j.1551-8833.1998.tb08362.x.Google Scholar
Kenney, T. Van Veen, W. Swallow, M. and Sungaila, M., (1992) Hydraulic conductivity of simulated sand-bentonite mixtures Canadian Geotechnical Journal 29 364–374 10.1139/t92-042.Google Scholar
Komine, H. and Ogata, N. (1996) Observation of swelling behavior of bentonite by new electron microscope. Proceedings of the 2nd International Congress on Environmental Geotechnics, Osaka, Japan, pp. 563–568.Google Scholar
Mollins, L. Stewart, D. and Cousens, T., (1996) Predicting the hydraulic conductivity of bentonite-sand mixtures Clay Minerals 31 243–252 10.1180/claymin.1996.031.2.10.Google Scholar
Vallejo, L., (2001) Interpretation of the limits in shear strength in binary granular mixtures Canadian Geotechnical Journal 38 1097–1104 10.1139/t01-029.Google Scholar