On capillary bridges in wet granular materials

The properties of wet granular materials are significantly influenced by the presence of microscopic liquid (capillary) bridges between the constituent granules. However, despite the progress which has been made in recent years the dependence of the mechanical properties of such materials on the amount and type of liquid present is still not completely understood. At a very basic level, a better understanding of the distribution of liquid between particle contacts and particle surfaces is required. Here we describe some of our observations on liquid bridge coordination numbers and liquid bridge volumes in model granular materials consisting of glass beads. We also describe experiments on the dynamic deformation of a wet granular material, which reveal a type of shear-thinning behavior that we attribute to the shear-rate dependence of liquid bridge volumes