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This article in SSSAJ

  1. Vol. 26 No. 2, p. 153-155
    Received: May 19, 1961
    Accepted: Oct 31, 1961

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Chemical Relationships Affecting the Water-Holding Capacities of Clays1

  1. Grant W. Thomas and
  2. John E. Moody2



The relation between water-holding capacity and clay properties was studied on Wyoming bentonite and four Virginia soil clays ranging in mineralogical type from montmorillonite to kaolinite. The amount of water held at 1/3 atm. pressure was closely related to clay type and cation saturation; the Na-montmorillonites containing much more water than any other clays. At 15-atm. pressure there was little difference in water held between any of the clays regardless of cation saturation or clay type. The only exception was Na-bentonite which held 71% H2O compared to a mean of 48.6 ± 3.2% among all the other clays. Analyses of displaced solutions from the clay suspensions showed that only in Na-montmorillonites was the predicted double-layer pattern of reduced anion concentration at lower water contents followed. This and the fact that other clays apparently did not imbibe much water between layers support the idea that the double-layer theory is applicable only to freely-expandable clay minerals.

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