fire protection of concrete structures exposed to fast fires

Fourth International Symposium on Tunnel Safety and Security, Frankfurt am Main, Germany, March 17-19, 2010
aggregates. These aggregates are crushed rocks with a content of almost 99 % of CaO. The second
concrete, that we called B40SC, is fabricated with a mix of calcareous and siliceous aggregates. These
silico-calcareous aggregates are composed by alluvial semi-crushed sand and limestone gravels.
Testing two types of aggregates allows analysing the fire behaviour of the most common concretes
that one may use in France. Moreover, previous studies have shown that the behaviour of concrete at
high temperature is strongly dependant on the nature of the aggregates [13].
The composition of the two types of concretes used for the study is given in Table 2. It is in
conformity with standard NF EN 206.
kg Calcareous concrete Silico-calcareous concrete
CEM II 42.5 R cement 350 350
8/12.5 calcareous gravel 330
12.5/20 calcareous gravel 720
4/8 silico-calcareous gravel 150
8/20 silico-calcareous gravel 890
0/2 sand 845 845
Water 188 188
Superplasticizer 4.31 5.25
W / C ratio 0.54 0.54
28 days Rc [MPa] 39 40
Table 2. Composition of the two concretes of the study
3.3 Unloaded tests
During the same fire test, both concrete types (calcareous and silico-calcareous) were tested (see
Figure 3). In parallel with the thermal data collection, a video camera placed inside of the furnace was
capturing all moments and brought very useful information of the moment and the way concrete
spalling occurred.
Figure 3. The testing furnace in Promat laboratory (left) and the design of the construction for testing (right).
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