Blasting Definitions
Document type: EEG Guide
Categories: Explosive Engineers Guide, America

Airblast: The airborne shock wave or acoustic transient generated by an explosion.

Backbreak: Rock broken beyond the limits of the last row of blastholes. Same as overbreak.

Blast Area: The area of the blast within the influence of flying rock, gases, and concussion.

Blaster-In-Charge: The blaster who is in charge of and responsible for the design, loading and firing of a blast at a specific job site.

Blast Site: The area where explosive material is handled during loading of blastholes including 50 feet in all directions from the perimeter formed by loaded blastholes.

Blasting Agent: A mixture intended for blasting that cannot be detonated with a No. 8 detonator when unconfined and has very little probability of detonation under normal conditions in transport.

Blasting Log: A written record of information about a specific blast as may be required by law.

Bootleg: The end of a blasthole remaining when the explosion does not break the rock completely.

Booster An explosive charge in the initiation sequence between the initiator and main charge.

Borehole: Pressure The pressure which the gasses of detonation exert on the borehole wall.

Burden: The linear dimension between the blasthole and the nearest free face.

Critical Diameter The minimum diameter for propagation of a stable detonation.

Cutoff: A break in the path of detonation or initiation caused by extraneous interference.

Date-Shift Code: A code required by the BATF on explosives packaging to aid in identification.

Decoupling: The use of explosives having a smaller volume than the volume of the blasthole.

Deflagration: An explosive reaction that moves at a velocity less than the speed of sound.

Delay Blasting: Use of delay detonators or connectors to separate charges by a defined time.

Detonation: An explosive reaction that moves at a velocity greater than the speed of sound.

Detonation Pressure: The pressure produced in the reaction zone of a detonating explosive.

Detonation Velocity: The speed at which a detonation progresses through an explosive.

Detonator Sensitive Explosive: An explosive that detonates with a No. 8 detonator when unconfined. Same as Cap Sensitive Explosive.

Effective Burden: The distance between a blasthole and the position of the nearest free face at the time of detonation of the blasthole, taking into consideration the direction of initiation.

Effective Spacing: The linear dimension between successively detonating blastholes, taking into consideration the direction of initiation.

Electric Detonator: A detonator that is initiated by electric current.

Electronic Detonator: A detonator that utilizes stored electrical energy to power an electronic timing element and to fire the base charge.

Emulsion Explosive: A stabilized dispersion of small droplets of an aqueous oxidizer solution (the internal phase) surrounded by a continuous oil and/or wax external phase, which is sensitized by air voids or sensitizing agents.

Explosive Density: The mass of an explosive per unit of volume,expressed in g/cc or lbs/ft 3 .

Free Face: A rock surface that provides the rock with room to expand when blasted.

Flyrock: Rocks propelled from the blast area by the force of an explosion.

Fumes: The gaseous products of an explosion. To determine fume classification of explosive materials, only poisonous or toxic gases are considered.

Gap Sensitivity: The gap across which a detonation will travel to initiate a second charge.

Ground Vibration: Shaking of the ground by elastic waves emanating from a blast; usually measured in inches per second of particle velocity.

Hangfire: The detonation of an explosive charge some time after its expected firing time.

Highwall: A nearly vertical face at the edge of the bench, bluff or ledge on a surface excavation.

Initiation: The start of deflagration or detonation in an explosive by any means.

Misfire: A blast, explosive charge or specific blastholes that failed to detonate as planned.

Nonelectric Detonator: A detonator that does not require the use of electric energy to function.

Overbreak: Rock broken beyond the limits of the last row of holes. Same as backbreak.

Permissible: Explosives approved for use in gassy and dusty atmospheres, usually underground.

Preblast Survey: Documentation of the existing condition of structures near an area to be blasted.

Repumpable Emulsion: A previously manufactured bulk emulsion with sufficient shelf life and fluidity to be pumped, with reasonable pressures, through a hose without deterioration in performance.

RF Energy: The energy radiated as electromagnetic waves in the radio frequency spectrum.

Primer: A unit of explosives containing a detonator used to initiate other explosives.

Presplit: A controlled blast in which decoupled charges are fired in blastholes on the perimeter of the excavation prior to firing the main charge to prevent backbreak (overbreak).

Relative Bulk Strength (RBS): The energy per unit volume of an explosive compared to ANFO when ANFO = 1.00 at a density of 0.82 g/cc.

Relative Weight Strength (RWS): The energy per unit mass of an explosive compared to ANFO when ANFO = 1.00 at a density of 0.82 g/cc.

Scaled Distance: A factor relating blast effects from explosive charges at various distances.

Shelf Life: The maximum storage period during which an explosive retains adequate performance.

Shunt: The shorting together of the free ends of electric detonator legwires or a blasting circuit.

Steady State Velocity: The final velocity of detonation achieved by a specific explosive at a given diameter, density and degree of confinement.

Stemming: Inert material (crushed rock) used to confine the gasses generated during detonation.

Swell Factor: The ratio of the volume of broken rock to the volume of in-situ rock.

Watergel Explosive: A thickened (and optionally crosslinked) aqueous oxidizer solution containing dissolved and/or dispersed fuels, which is sensitized by air voids or sensitizing additives.