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This article in SSSAJ

  1. Vol. 43 No. 4, p. 782-785
    Received: Jan 9, 1978
    Accepted: Mar 26, 1979

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Particle Shape and Size of Two Sodium Calcium Montmorillonite Clays1

  1. Joseph E. Dufey and
  2. Amos Banin2



Viscosity measurements of Na-Ca montmorillonite suspensions (Wyoming and Camp-Berteau) were performed at five temperatures (11 to 35°C). At a given composition of the surface phase, discontinuous variations of intrinsic viscosity were observed with changing temperature. According to similar observations from the literature, variations would be due to structural modifications of water layers surrounding the clay particles.

By combining those results with optical density spectra, we have pointed out different characteristics for the Wyoming and Camp-Berteau clays. The single plates of Camp-Berteau montmorillonite are smaller than those of Wyoming. At high Ca-loading, the formation of thicker particles by parallel condensation of single plates does not involve any marked increase of average major axis in the case of the Wyoming clay. On the other hand, the Camp-Berteau plates are likely to overlap when they condense; that results in an increasing major axis with increasing Ca-loading, leading to similar shapes for both pure Ca-clays. Those results were confirmed by measurements of water content in clay sediments.

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