Three-Step Relaxation in Stabilized Dense Suspensions

Stabilized dense suspensions of solid particles in Newtonian fluids exhibit a variety of non-Newtonian behaviors depending on the shear stress applied to the suspension and the particle mass fraction. Suspensions at sufficiently high particle concentration shear-thicken dramatically and can even exhibit solid-like behavior. How dense suspensions relax out of such stressed rheological states, however, is not well understood. Using a texture analyzer, we vary the parameters of the stressed states and measure the suspension’s relaxation response. We find three distinct relaxation regimes; a rapid high stress decay followed by two exponential decay regimes. Combining our findings with rheological data allows us to establish the mechanisms governing each regime.