Chapman-Jouguet Pressure
Definition
The detonation pressure at the reaction zone/product interface in a steadily propagating detonation. For ANFO at operational density, approximately 5 GPa (versus 30+ GPa for RDX). The lower CJ pressure reduces brisance and confines ANFO effectiveness to bulk charge applications in large-diameter boreholes.
- Location measured
- Reaction zone/product interface
- ANFO value
- ~5 GPa
- RDX value
- 30+ GPa
- Effect of lower CJ pressure
- Reduced brisance
Common questions
Why does lower CJ pressure limit ANFO's applications?+
Brisance is the shattering, high-speed fragmentation effect useful for cutting or breaching hard materials, and ANFO's much lower CJ pressure means it lacks that shattering power, so it is used instead for bulk heaving in large-diameter boreholes.
How does CJ pressure inform post-blast investigation?+
Damage characteristics such as fragmentation pattern and crater shape correlate with the CJ pressure of the explosive used, so investigators use these observed effects alongside residue analysis to help identify the explosive type.
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