Detonation velocity and pressure measurements were performed for heterogeneous mixtures consisted of packed beds of aluminum particles saturated with pure nitromethane using aluminum particles of 3 different sizes. In case of packed beds of aluminum particles of 30 and 110mum size, critical diameter was greatly decreased as in case of nitromethane containing small concentration of aluminum particles. Measured detonation velocity and pressure were compared with calculated values obtained by KHT code. Difference between measured and calculated detonation properties provides the evidence for lack of equilibrium between aluminum particles and detonation products of nitromethane.