A three-dimensional grain model based on the concept of particles assembly using cohesive bonds is presented. A script was written to generate polyhedral grains, by assembling tetrahedral particles using cohesive bonds. A series of single grain crushing simulations is performed, and the effect of the intra-granular cohesion on the grain's strength is studied. dometric compression tests are simulated.The effect of grain breakage on the macroscopical behaviour is evaluated