UBC Theses and Dissertations
Effect of salt concentration and cation valence on maximum yield of a bentonite claypaste Hu, Chien-Sheng
A review is given on the factors important to the build-up of a gel structure in clay suspensions. The effect of salt is especially stressed. The maximum yield stress of a 19.06 weight per cent washed Bentonite clay paste was measured with a Rotovisco viscometer as a function of the concentration of five salts which were added individually to the paste. The salt concentration was varied from .002 molality up to the coagulation concentration. Two groups of salts were studied; those which had cations in common with the caly: NaCl and CaCl₂, and those found only in trace amounts in clay: CuCl, MnCl₂ and CeCl₃. The behavior of the two groups of salt was quite different. The latter group produced a maximum developable yield value in the clay which was inversely proportional to the valence of the cation. Sodium Chloride produced the largest maximum yield value at a high salt concentration while no yield value could be found for clay with concentrations of CaCl₂ above 0.002M.
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