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Published online by Cambridge University Press: 09 July 2018
The flow behaviour of Wyoming bentonite dispersions was studied in water and water-alcohol mixtures (methanol, ethanol, n-propanol) with or without the addition of NaCl. The yield value τo and relative apparent viscosity τ*rel (= τ* (dispersion/τ* (medium) at γ = 94.5 s-1) increase to a maximum and then decrease with increasing alcohol content. The increase of the flow values is caused by face-to-face aggregation. Formation of band-type networks is a consequence of the enhanced attraction between the silicate layers in water-alcohol mixtures. At higher alcohol contents the bands are contracted to discrete particles. Both effects are considerably strengthened by calcium ions which are present in the crude bentonite.