  The elastic properties of a soft matter material can be greatly altered by
the presence of solid inclusions whose microscopic properties, such as their
size and interactions, can have a dramatic effect. In order to shed light on
these effects we use extensive rheology computer simulations to investigate
colloidal gels with solid inclusions of different size. We show that the
elastic properties vary in a highly non trivial way as consequence of the
interactions between the gel backbone and the inclusions. In particular, we
show that the key aspects are the presence of the gel backbone and its
mechanical alteration originated by the inclusions. To confirm our observations
and their generality, we performed experiments on an emulsion that presents
strong analogies with colloidal gels and confirms the trends observed in the
simulations.
