  We study the impact between a plate and a drop of non-colloidal solid
particles suspended in a Newtonian liquid, with a specific attention to the
case when the particle volume fraction, $\phi$, is close to - or even exceeds -
the critical volume fraction, $\phi_c$, at which the steady effective viscosity
of the suspension diverges. We use a specific concentration protocol together
with an accurate determination of $\phi$ for each drop and we measure the
deformation $\beta$ for different liquid viscosities, impact velocities and
particle sizes. At low volume fractions, $\beta$ is found to follow closely an
effective Newtonian behavior, which we determine by documenting the low
deformation limit for a highly viscous Newtonian drop and characterizing the
effective shear viscosity of our suspensions. By contrast, whereas the
effective Newtonian approach predicts that $\beta$ vanishes at $\phi_c$, a
finite deformation is observed for $\phi>\phi_c$. This finite deformation
remains controlled by the suspending liquid viscosity and increases with
increasing particle size, which suggests that the dilatancy of the particle
phase is a key factor of the dissipation process close to and above $\phi_c$.
