Rupturing of bitumen-in-water emulsions: experimental evidence for viscous sintering phenomena

In this paper, we present experimental evidence for viscous sintering phenomena in a gel formed by bitumen emulsion droplets. When a destabilizing agent is added to the initially stable emulsion, a gel forms, which, further contracts by preserving the geometry of the container. The observed contraction phenomenon is reminiscent of the classical sintering process in ceramics, aerogels, etc. We study the shape relaxation of two coalesced droplets using a micropipette technique as well as the contraction kinetics of the macroscopic gel. The linear dependence of the contraction rate on the viscosity of the bitumen is in agreement with the classical viscous sintering theory.