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C-4 or Composition C-4 is a common variety of military plastic explosive.
The term composition is used for any stable explosive, and "Composition A" and "Composition B" are other known variants. C-4 is 1.34 times as explosive as trinitrotoluene (TNT).
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Composition
C-4 is made up of explosives, plastic binder, plasticizer and, usually, marker or taggant chemicals such as 2,3-dimethyl-2,3-dinitrobutane (DMDNB) to help detect the explosive and identify its source.
As with many plastic explosives, the explosive material in C-4 is RDX (cyclonite or cyclotrimethylene trinitramine) which makes up around 91% of the C-4 by weight. The plasticizer is diethylhexyl or dioctyl sebacate (5.3%) and the binder usually is polyisobutylene (2.1%).
Another plasticizer used is dioctyl adipate (DOA). A small amount of SAE 10 non-detergent motor oil (1.6%) is also added. C-4 detonates with a pressure wave of about 8,040 m/s (26,400 ft/s), or 28,900 km/h (18,000 mph).
C-4 is manufactured by combining RDX slurry with binder dissolved in a solvent. The solvent is then evaporated and the mixture dried and filtered. The final material is an off-white solid with a feel similar to modelling clay. The plasticized form of RDX, composition C-4, contains 91% RDX, 2.1% polyisobutylene, 1.6% motor oil, and 5.3% 2-ethylhexyl sebacate.
The Demolition charge M183 is used primarily in breaching obstacles or demolition of large structures where large charges are required (Satchel Charge). The charge assembly M183 consists of 16 block demolition charges M112, four priming assemblies and carrying case M85. Each Priming assembly consists of a five-foot length of detonating cord assembled with two detonating cord clips and capped at each end with a booster. The components of the assembly are issued in the carrying case. The demolition charge M112 is a rectangular block of Composition C-4 approximately 2 inches (51 mm) by 1.5 inches (38 mm) and 11 inches (280 mm) long, weighing 1.25 lb (0.57 kg). When the charge is detonated, the explosive is converted into compressed gas. The gas exerts pressure in the form of a shock wave, which demolishes the target by cutting, breaching, or cratering.
Using explosives provides the easiest and fastest way to break the frozen ground. Composition C-4, tetrytol, and TNT are the best explosives for use in northern operations because they retain their effectiveness in cold weather. Dig a hole in the ground in which to place the explosive and tamp the charge with any material available to increase its effectiveness. Either electric or nonelectric circuits may be used to detonate the charge. For a "foxhole", 4.6 kg (10 lb) of explosive will usually be sufficient. Another formula is to use 2 pounds (1 kg) of explosive for every 30 cm (1 ft) of penetration in frozen ground.
Advantages
A major advantage of C-4 is that it can easily be molded into any desired shape. C-4 can be pressed into gaps, cracks and voids in buildings, bridges, equipment or machinery. Similarly, it can easily be inserted into empty shaped-charge cases of the type used by military engineers, pioneers and special forces. C-4 is very stable and insensitive to most physical shocks. It can only be initiated by a combination of extreme heat and a shockwave i.e. when the detonator inserted into it is fired. C4 cannot be detonated by a gunshot or by dropping it onto a hard surface.
International usage
British Military plastic explosive is referred to as PE4. Like C-4, it is an off-white colored solid and its explosive characteristics are nearly identical to C-4. The only difference between C-4 and PE4 is the type and proportion of plasticizer used. Very similar to the British PE4 is the Italian military plastic explosive referred to as T4.
Because C-4 burns slowly when it is ignited with a flame rather than detonated with a primary explosive, soldiers during the Vietnam War era would sometimes use small amounts of C-4 as fuel for heating rations while on long patrols.1 While many soldiers used C-4 safely in this manner, there are several anecdotes about soldiers attempting to put out the fire by stomping on it — causing it to detonate.citation needed While C4 will not actually detonate in these circumstances, burning C4 produces poisonous fumes and should be avoided (see below).
Michael Herr in Dispatches, his book about the Vietnam War, relates that a soldier would occasionally ingest C-4 from a claymore mine in order to cause temporary illness and be sent on sick leave. Although the ruse might work with an inexperienced commander, experienced officers were usually aware of the trick and would keep the man on board.citation needed
The preceeding two "uses" of C4 are highly dangerous and potentially fatal. US Army Field Manual 5-250, Explosives and Demolitions includes this bold print, block warning: "WARNING Composition C4 explosive is poisonous and dangerous if chewed or ingested; its detonation or burning produces poisonous fumes." These "uses" of C4 should be strictly avoided.
C4 has been featured in several motion pictures and video games (e.g. Die Another Day - opening sequence detonation of briefcase of diamonds).
References
External links
- Commercial C4 supplier information, showing characteristics and cost per kilo
- HowStuffWorks article
- Autobiographical page of a Vietnam veteran Includes mention of C-4 used for demolition.
Wikipedia content modification information:
- This page was last modified on 8 January 2009, at 20:27.
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