Plastic explosives
Plastic explosive is a soft and hand-moldable solid form of explosive material. Within the field of explosives engineering, plastic explosives are also known as putty explosives.
Plastic explosives are especially suited for explosive demolition. Common plastic explosives include Semtex and C-4. The first discovered plastic explosive was gelignite in 1875, invented by Alfred Nobel.
Plastic explosives are especially suited for explosive demolition of obstacles and fortifications by engineers, combat engineers and criminals as they can be easily formed into the best shapes for cutting structural members and have a high enough velocity of detonation and density for metal cutting work.
An early use of plastic explosives was in the warhead of the British Armoured Vehicle Royal Engineers's (AVRE)'s Petard demolition mortar, used to destroy concrete fortifications encountered during Operation Overlord (D-Day). The original use of Nobel 808 supplied by the SOE was for sabotage of German installations and railways in Occupied Europe.
They are generally not used for ordinary blasting as they tend to be significantly more expensive than other materials that perform just as well in this application. A common commercial use of plastic explosives is for shock hardening high manganese percentage steel, a material typically used for train rail components and earth digging implements.
...
Wikipedia