The basic constitutive properties of granular materials depend on their grading. Crushing or breakage of particles under compression or shear modify the grain size distribution, with a tendency for the percentage of fine material to increase. It follows that the frictional properties of the material and the critical states are modified as a consequence of the changes in grain size distribution and the available range of packing densities. This paper shows the results of an experimental investigation of the evolution of the grading of an artificial granular material, consisting of crushed expanded clay pellets, most commonly known under the brand name LECA, under different loading conditions. The changes of grading of the material after isotropic, one-dimensional and constant mean effective stress triaxial compression were described using a single parameter based on the ratio of the areas under the current and an ultimate cumulative particle size distribution which were both assumed to be consistent with self similar grading with varying fractal dimension.