Concrete structures need post-fire analysis, because when exposed to high temperatures and to thermal shock by sudden cooling, they can present immeasurable damage, which is the subject proposed in the work. Therefore, besides comparing the values obtained with those of the reference CP's, they correlated with the data of the theoretical reference in order to verify the loss of resistance of the abruptly cooled concretes. The concrete with Fck of 35 and 40MPa presented higher loss of resistance, if compared to the concrete with Fck of 25MPa. At temperatures of 900 and 1200ºC, the percentage of loss is equal to the concrete with Fck of 25MPa. This refers to the fact that the more resistant the concrete is, the greater the percentage loss and the incidence of Explosive Spalling. In view of the results, it can be concluded that heating and cooling interfere with the physical-chemical properties and microstructure of the concrete, favoring the emergence of micro-cracks and consequently affecting the characteristic resistance of the concrete.