Rheology of bentonite dispersions: Role of ionic strength and solid content

Abstract The rheological behavior of the bentonite dispersion was studied at different ionic strength and solid content. The yield and flow behavior of the dispersion changed with both the ionic strength and the solid content. Curves of the equilibrium viscosity normalized by two characteristic parameters, namely, the yield stress and the characteristic viscosity, formed a master curve. The electrostatic interaction reflected by the yield stress hindered the orientation/alignment of clay platelets estimated by the characteristic viscosity, giving rise to a power law relationship between the two characteristic parameters. Models based on the DLVO (Derjaguin and Landau, Verwey and Overbeek) theory were developed to describe the change of the yield stress and the characteristic viscosity as functions of both ionic strength and bentonite solid content. The master viscosity curve allows viscosity curves at different solid content and ionic strength to be determined once the yield stress and the characteristic viscosity of the dispersion are known. A constitutive model for the master viscosity curve as a function of the normalized shear stress and rate was proposed.