Rheological behaviour of concentrated bimodal suspensions2: Influence of quartz and deflocculant content on clay suspension viscoelasticity

Abstract

Suspensions were prepared with mixtures of quartz and clay in different states of deflocculation for much broader solids volume fraction ranges than those found in the literature. Viscoelastic behaviour was determined by small amplitude oscillatory tests. The study shows that adding quartz to a colloidal suspension, suspending medium, raises the value of the elastic component G′, as well as that of the viscous component G″. This effect becomes more pronounced as suspension quartz content rises and deflocculant content decreases. For the studied system, at moderate quartz contents, the G″/G′ ratio, which is directly related to the material's viscoelastic type of behaviour, depends almost exclusively on the deflocculation state of the starting clay suspension. The quartz content has a minor effect on this ratio. These results validate the applicability of the bimodal model to clay suspensions in very different states of deflocculation, with very different coarse particle contents.