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Experimental study of swelling in unsaturated compacted clays

Authors
  • Saiyouri, N.
  • Tessier, D.
  • Hicher, P. Y.
Type
Published Article
Journal
Clay Minerals
Publisher
The Mineralogical Society
Publication Date
Dec 01, 2004
Volume
39
Issue
4
Pages
469–479
Identifiers
DOI: 10.1180/0009855043940148
Source
De Gruyter
Keywords
License
Yellow

Abstract

This paper describes the swelling properties of two highly compacted clays, natural, untreated Wyoming montmorillonite (MX80) and Fourges smectite (FoCa7), saturated with Na and Ca, respectively. The initially compacted samples were hydrated by subjecting them to different suction pressures in a range between 100 MPa and 1 kPa. For each equilibrium state, the volume change (swelling) and water content (hydration) were measured. The samples were then studied by X-ray diffraction using a transmission device to determine interlayer distance and particle size, in order to clarify both the swelling and hydration mechanisms. The distances between clay layers ranged between 10 and 21.6 Å , i.e. corresponding to between 0 and 4 water layers. Upon hydration, the particle size decreased from 350 and 100 clay layers per particle to 10 layers per particle when the suction pressure decreased from 100 MPa to 1 kPa for MX80 and FoCa7, respectively. The first swelling stage is described as being an insertion of water molecules between the layers. Then a division of the initial particles into particles of smaller size with increasingly large inter-particle distances was observed. Observations by transmission electronic microscopy confirmed these results.

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