
Save your favorites
Select and save the products and documents you need for your projects
Spalling is an umbrella term, covering different damage phenomena that may occur to a concrete structure during fire. These phenomena are caused by different mechanisms:
In different combinations of these mechanisms, possible spalling phenomena include:
Spalling of concrete during fire causes serious damage to concrete structures, with significant economic costs and risk to human life.
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 spalling 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 spalling and the non-operational time of tunnels after a fire, the fire resistance of newly developed concrete types has been questioned.
During 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.
In the paragraphs below the different observed spalling phenomena are described and related to these mechanisms, see also Breunese and Fellinger (2003).
A summary of these relations is given in the table below.
Pore pressure due to evaporation of moisture | Compression due to thermal gradient | Internal cracking due to different thermal expansion aggregate - cement paste | Cracking due to different thermal deformation concrete - steel | Strength loss due to chemical transitions | |
Violent Spalling | x | x | x | ||
Sloughing Off | x | x | |||
Corner Spalling | x | ||||
Explosive Spalling | x | x | |||
Post-Cooling Spalling | x | x |
Contact our technical support team with your questions on passive fire protection solutions, our products and systems or installation advice...
Find the product datasheets, system brochures, Declarations of Performance, installation manuals and other documents you need to get the job done.