Tertiary Explosive (Blasting Agent)
Definition
An ammonium nitrate-based explosive formulation requiring both a primary and a booster charge for reliable initiation. ANFO is the globally dominant blasting agent. Too insensitive to be detonated by a blasting cap alone.
- Base composition
- Ammonium nitrate-based formulation
- Initiation need
- Primary charge plus a booster
- Common example
- ANFO
- Sensitivity
- Too insensitive for a blasting cap alone
Common questions
Why is low sensitivity treated as an advantage?+
A tertiary explosive resists accidental initiation from friction, shock or flame, which makes it much safer to manufacture, transport and store in bulk than a primary or secondary explosive of equivalent power.
How does a tertiary explosive differ from a secondary one?+
A secondary explosive like TNT or PETN can be set off directly by a detonator, while a tertiary explosive needs an intermediate booster charge of secondary explosive to build up enough shock energy to detonate reliably.
Related terms
- ANFO
- Ammonium nitrate fuel oil: 94% ammonium nitrate prills + 6% diesel fuel oil. Detonation velocity approximately 4,500-4,800 m/s. The most widely used...
- Brisance
- The shattering power of a detonating explosive, distinct from heave (bulk displacement). Measured by the Trauzl lead block test. High-brisance explosives (RDX,...
- Deflagration
- A subsonic combustion front propagating through an explosive by thermal conduction. Characteristic of low explosives such as black powder and smokeless powder;...
- Deflagration-to-Detonation Transition (DDT)
- The acceleration of a deflagrating burn front to supersonic detonation velocity, triggered by confinement. Relevant to understanding how improvised devices using low...
- Detonation
- A supersonic shock wave coupled to a chemical reaction front, propagating through a high explosive at velocities between approximately 4,500 and 9,100...
- Ion Chromatography (IC)
- An analytical technique that separates and quantifies anions and cations in solution. In post-blast residue analysis, IC detects nitrate, nitrite, ammonium, and...
- Primary Explosive
- A high explosive sensitive enough to detonate from friction, spark, percussion, or flame without confinement or a separate booster. Examples: mercury fulminate,...
- Secondary Explosive
- A high explosive insensitive to normal friction, spark, and percussion; requires a primary explosive shock or blasting cap to initiate detonation. Examples:...
- TNT Equivalent
- A normalised measure of explosive energy output relative to trinitrotoluene (TNT equivalent = 1.0). Used to compare blast yields across different explosive...