Influence of the rheology of liquid bridges on wet granular materials

Introducing a slight amount of liquid in a granular material results in a drastically different behavior. This is, for instance, illustrated by sandcastles on the beach, where capillary bridges between particles introduce a cohesive force. Yet, the role of the rheology of the liquid constituting the capillary bridges between the particles remains poorly explored, in particular when the wet granular material is flowing. In this study, we consider macroscopic experiments with the canonical configuration of the collapse of a wet granular column for different liquid viscosities. We couple these experiments with force measurements at the microscopic scale between individual particles to elucidate the influence of the nature of the liquid on the granular flow. Understanding the interactions between particles and liquids, in particular for non-Newtonian fluids, could help to develop better modeling of grain mixing processes in the industry, such as the mixing of slurries in battery manufacturing, silver pastes used in solar panels, and in the environment to account for biocohesion.