Explosive residues from low-order detonations of heavy artillery and mortar rounds

Low-order detonations are produced by artillery and mortar rounds that fail to function as intended. The unconsumed residual explosive constitutes a potentially significant source of explosives for environmental receptors. The objectives of this study were to relate residue mass to detonation pressure, to define the relationship between the residue mass and distance from the detonation center, and to determine particle size distribution and composition of residues. Three types of mortar and two heavy artillery rounds were detonated by specific donor charges. Detonations were executed on a tarp so that residues could be recovered by sweeping. No consistent relationship was demonstrated between residue mass and measured detonation pressure. Furthermore, no consistent differences in deposition with distance from the detonation center were observed. Most of the recovered mass was in the 12.5-mm size fraction; very little was in the 0.25-mm size fraction. The ratio of RDX to TNT in the original Composition B was conserved in the residues. Results illustrate that significant quantities of explosive residues can result from low-order detonations. The particle size distribution and chemical composition of the explosive residues can be used to evaluate their future environmental fate and transport.