Concrete spalling effect

Spalling of concrete during fire causes serious damage to concrete structures, with significant economic costs and risk to human life. This is called the concrete spalling effect.

New developments in concrete technology like improved grain size distributions and the application of extra fine particles have resulted in concrete types with improved durability, strength and workability. However, these high performance concrete types have shown to be more susceptible to spalling during fire than ordinary concrete types.

The problem of the concrete spalling effect in buildings has been known for decades, but also has been highlighted in recent intense tunnel fires in Europe. As a consequence of severe damage due to the concrete spalling effect and the non-operational time of tunnels after a fire, the fire resistance of newly developed concrete types has been questioned.

During standard fire tests the observations of spalling of concrete cover a wide range, in random order: observation of spalling with slow (1ºC/min.) or fast (250ºC/min.) heating, from gradual to explosive spalling, cracking along or through aggregate grains, spalling in the beginning of the fire or after some time, stopping after some time or progressing, stopping at the reinforcement level or continuing far beyond it, and so on.

Standard fire tests
Concrete spalling effect
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