Rheological behaviour of pure clay and coarse-grained clay suspensions using an inclined blade vane-in-cup

Abstract

Mixtures of clay and sand suspended in water are complex systems encountered in many industrial and environmental applications, but their understanding and modelling are still limited and require further investigations. In this way, the rheological behaviour of pure non-thixotropic clay and coarse-grained clay suspensions is investigated with a rotational rheometer equipped by an inclined blade vane-in-cup, where the type and the volume fraction of both fine clay and coarse materials are varied. The Herschel–Bulkley model τ = τ y + K γ ̇ n is used to describe successfully the flow curves of suspensions relating the shear stress τ to the shear rate γ ̇ , from which the yield stress τ y , the consistency K and the index n are deduced. The main contributions of this study are (i) to validate the inclined blade vane-in-cup for the estimation of the rheological behaviour of polymer microgels, pure clay suspensions, and coarse-grained clay suspensions, (ii) to conclude on the most appropriate model type to predict the yield stress of pure clay suspensions over a wide range of fine clay volume fractions, and (iii) to highlight how frictional contacts of coarse grains may play a role on the bulk yield stress of coarse-grained clay suspensions. We believe that this work would be useful for improving the rheological description of cohesive suspensions in geophysical and industrial applications. • Rheological measurements are performed on pure clay and coarse-grained clay suspensions. • The inclined blade vane allows to estimate the rheology of complex fluids containing grains. • The most appropriate models are provided to quantify the yield stress of suspensions. • The type of coarse materials may affect the bulk yield stress due to frictional contacts.