Blast-induced fines often negatively influence economics and environment. The Austrian Science Fund (FWF) sponsors a project to investigate the cause of the fines by studying blast fragmentation of cylinders by means of experimental tests and by numerical simulations. The tests include blast loading confined rock or mortar cylinders by detonating cord with 6, 12 and 20 g/m of PETN. The
blast-driven radial cracking with branching and merging at the end face of the cylinder opposite to the initiation point is filmed by means of high-speed photography at 20,000-37,000 frames per second (fps). The filming is followed up by CT scanning of the internal crack systems. The investigation will also include sieving of specimens that have been broken open to quantify the amount of fine material created. The paper describes the test set-up, the resulting crack development and patterns, and how these might be related to the generation of the fines.