Blast Wave Characteristics and TNT Equivalent of Improvised Explosive Device at Small scaled Distances

Abstract

A significant number of airblast test have been carried out with the purpose to characterise and analyse the properties of improvised explosive device (IED) with non-conventional explosives in terms of knowing the effects on people and/or structures. Small devices with 1.5 kg of explosive, initiated with a detonating cord have been studied. Seven different mixtures have been tested with two types of ammonium nitrate AN (technical and fertilizer) in different forms like prills or powder. In some cases, the ammonium nitrate has been mixed with fuel oil while in others, it has been mixed with aluminum. The TNT equivalent based on pressure, impulse, arrival time, positive phase duration and shock front velocity have been calculated and analysed for each mixture. Comparing the field test data obtained with respect to the representation of the UFC 3-340-02 values, it can be seen that the parameters measured are consistent. The IEDs with fertilizer ammonium nitrate do not detonate with the present charge conditions so the shockwave generated is only due to the detonating cord. When using the technical ammonium nitrate, ANFO can partially detonate and generate a potentially dangerous shockwave. Finally, the IED with AN and aluminum produces a TNT equivalent close to one when the technical AN is used.