In order to investigate the breakage behaviour of inhomogeneous particulate products such as fine agglomerates i.e. granules, their structural inhomogeneity has to be taken into consideration. In this article, considering the contact at each load during repeated loading, we describe from a micro-mechanical perspective, the differences in the contact area, contact stiffness and fatigue, and from an energetic perspective, the differences in the breakage probability. As model test materials, Geldart D elasto-plastic gamma-Al2O3 granules had been selected and tested by quasi-static compression, low-velocity dynamic pendulum double-impact and high-velocity dynamic impact using a pneumatic cannon. Furthermore, we also describe the influence of preloading by double-impact on the breakage probability of granules subsequently loaded by dynamic impact. (C) 2014 Elsevier B.V. All rights reserved.