Flow characteristic of dilute Na montmorillonite suspension

The objective of this paper was to study the flow properties of dilute Na montmorillonite suspensions. Until now, a very dilute Na montmorillonite suspension has been treated as a Newtonian fluid. However, this paper shows a different behavior. Consistency curves of dilute suspensions, measured over different measuring times, may exhibit a different behavior from that of a perfect Newtonian fluid with a concentration of 33–36 kg/m3. The simple viscoelastic model a Maxwell model proposed by the authors in a previous paper analyzes this behavior. The theoretical analysis predicted that the consistency curve measured in au extremely short measuring time shows negative shear-rate thixotropy, and the loop disappears as time increases. The experimental results confirmed the validity of the analysis. The consistency curves of a dilute clay suspension over extensive measuring times allow estimation of the relaxation time and the shear modulus of the suspension as well as the coefficient of viscosity.