Starting from the formulae for effective parameters of the particulate composite derived within the average field approximation, the formula for the percolation threshold is derived. The maximum value of the percolation threshold is 1/3 in the case of the isotropic granules of globular shape. Further, the experimental data obtained from the measurement of effective thermal conductivity and elastic shear modulus of the particulate composite polyethylene-CaCO3 cannot be interpreted in the framework of the average field approximation. For this reason it was necessary to modify the formulae for effective parameters, and they were able to describe the experiment.