Spalling
Definition
Fracturing or chipping of concrete from rapid heating. Often misread as evidence of accelerant pour; usually a thermal phenomenon unrelated to ignitable liquids.
- Definition
- Fracturing or chipping of concrete from rapid heating
- Common misread
- Mistaken for evidence of accelerant pour patterns
- Actual cause
- Thermal phenomenon usually unrelated to ignitable liquids
- Field
- Fire and burn pattern interpretation
Common questions
Why is spalling so commonly mistaken for accelerant pour patterns?+
Both can produce irregular light or damaged patches on a concrete floor, and spalling can occur where an object sat and shielded the surface or where rapid temperature rise created internal steam pressure, which superficially resembles a poured-liquid burn pattern to an untrained eye, a confusion documented in fire investigation literature as a classic misinterpretation.
What actually causes concrete to spall in a fire independent of accelerants?+
Rapid heating vaporises trapped moisture within the concrete faster than it can escape, building internal steam pressure that fractures and pops off surface fragments, a mechanism driven by heating rate and moisture content rather than by any liquid poured on the surface.
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