| Description |
Adding small amount of wetting liquid to dry granulates typically leads to the granular stiness which arises due the formation of minute liquid contacts between individual granules by the virtue of capillary forces. We experimentally study the mechanical properties of wet granulates, composed of monodisperse spherical glass or basalt beads. The glass microspheres are almost perfectly wetted by water whereas the basalt microspheres have a rather large contact angles with water. The dierent wettability causes a dierence in the shape and volume distribution of the appeared liquid morphologies. We have investigated the shear strength, measured under cyclic shear deformation for various system parameters like liquid content, shear rate and absolute pressure. At large absolute pressures, the associated energy dissipation of a sheared wet granulate is considerably smaller than that of a completely dry bead assembly; where the wetting liquid might act as a `liquid lubricant' by lowering the wet bead pile's shear stiness. With time resolved X-ray microtomography, we could shed some light on the underlying microscopic mechanisms of sheared wet granulates.
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