  We study experimentally the behavior of isotropic suspensions of noncolloidal
particles in yield stress fluids. This problem has been poorly studied in the
literature, and only on specific materials. In this paper, we manage to develop
procedures and materials that allow us to focus on the purely mechanical
contribution of the particles to the yield stress fluid behavior, independently
of the physicochemical properties of the materials. This allows us to relate
the macroscopic properties of these suspensions to the mechanical properties of
the yield stress fluid and the particle volume fraction, and to provide results
applicable to any noncolloidal particle in any yield stress fluid. We find that
the elastic modulus-concentration relationship follows a Krieger-Dougherty law,
and we show that the yield stress-concentration relationship is related to the
elastic modulus-concentration relationship through a very simple law, in
agreement with results from a micromechanical analysis.

Soft Condensed Matter;Classical Physics