  Rheology of macroscopic particle-laden interfaces, called "Granular Rafts"
has been experimentally studied, in the simple shear configuration. The
shear-stress relation obtained from a classical rheometer exhibits the same
behavior as a Bingham fluid and the viscosity diverges with the surface
fraction according to evolutions similar to 2D suspensions. The velocity field
of the particles that constitute the granular raft has been measured in the
stationary state. These measurements reveal non-local rheology similar to dry
granular materials. Close to the walls of the rheometer cell, one can observe
regions of large local shear rate while in the middle of the cell a quasistatic
zone exists. This flowing region, characteristic of granular matter, is
described in the framework of an extended kinetic theory showing the evolution
of the velocity profile with the imposed shear stress. Measuring the
probability density functions of the elementary strains, we provide evidence of
a balance between positive and negative elementary strains. This behavior is
the signature of a quasistatic region inside the granular raft.
