Introduction To Explosives: William C. Davis
Introduction To Explosives: William C. Davis
Introduction To Explosives: William C. Davis
Introduction to Explosives
William C. Davis
Explosions are violent, sudden, noisy, and startling. The human brain resists
the thought that they are proper subjects for calm contemplation and detailed
physical modeling. An engineer or scientist who begins to use explosives must
subdue his or her startle reflex and aversion to loud noises, and consider
exactly how explosives work. To begin, let us survey the vast range of uses
for explosives, and the great variety in chemicals that explode.
1.1. History
Black powder has been known for centuries and used in small quantities
for mining after about A.D. 1650, and in larger quantities after 1800. Black
powder is extremely dangerous to use because it is so easily ignited by any
spark. Its action is unpredictable because the burning rate and the pressure
developed depend on the strength of the rock confining it. The economic
surge of the industrial revolution demanded ore mining in hard rock, cutting
defiles through hills for railroads and highways, and excavating and leveling
of older structures before construction of huge factories. Black powder could
not meet the needs.
Black powder is called a low explosive. It contains both the fuel and the
oxydizer in the mixture, and is what is now called an energetic material.
When it is ignited it burns, and the rate of burning increases as pressure
develops from the release of gases, increasing the pressure still more. The
maximum pressure is determined by the strength of the surroundings, the
bore hole, for example. High explosives detonate rather than burn, and in a
detonation the confinement that leads to high temperatures and very rapid
reaction is provided by the explosive itself. The reaction is so rapid that the
expansion, spreading in a wave propagating at the local speed of sound, is not
fast enough to reduce the pressure appreciably, and the reaction is inertially
confined by the explosive mass. Modern explosives are high explosives.
Detonating explosives have been known at least as long ago as the
fifteenth century, when the alchemist Blasius Valentius produced "fulmi-
J. A. Zukas et al. (ed.), Explosive Effects and Applications
© Springer-Verlag New York, Inc. 1998
2 1. Introduction to Explosives