The behavior of particulate composite materials, such as portland cement concrete, depends to a large extent on the properties of their main constituent-the aggregates. Among the most important parameters affecting the performance of concrete are the packing density and corresponding particle size distribution (PSD) of aggregates. Better packing of aggregates improves the main engineering properties of composite materials: strength, modulus of elasticity, creep and shrinkage. Further, it brings major savings due to a reduction in the volume of binder. A simulation algorithm was developed for the modeling of packing of large assemblies of particulate materials (of the order of millions). These assemblies can represent the real aggregate systems composing portland cement concrete. The implementation of the developed algorithm allows the generation and visualization of the densest possible and loose-packing arrangements of aggregates. The influence of geometrical parameters and model variables on the degree of packing and the corresponding distribution of particles was analyzed. Based on the simulation results, different PSDs of particulate materials are correlated to their packing degree.