Equilibrium concentration profiles and sedimentation kinetics of colloidal gels under gravitational stress

J Phys Condens Matter. 2012 Jul 18;24(28):284103. doi: 10.1088/0953-8984/24/28/284103.

Abstract

We study the sedimentation of colloidal gels by using a combination of light scattering, polarimetry and video imaging. The asymptotic concentration profiles (z,t → ∞) exhibit remarkable scaling properties: profiles for gels prepared at different initial volume fractions and particle interactions can be superimposed onto a single master curve by using suitable reduced variables. We show theoretically that this behavior stems from a power law dependence of the compressive elastic modulus versus , which we directly test experimentally. The sedimentation kinetics comprises an initial latency stage, followed by a rapid collapse where the gel height h decreases at constant velocity and a final compaction stage characterized by a stretched exponential relaxation of h toward a plateau. Analogies and differences with previous works are briefly discussed.

Publication types

  • Research Support, Non-U.S. Gov't