When concrete is subjected to high temperature it has a tremendous impact on loss of water which results in the expansive nature of concrete. Due to this the bond between the cement paste and aggregate is broken thereby leading to propagation of cracks in different direction. This cracks would pave a way for water seepage for eg.in dam resulting in uplift affects and finally the structural integrity fails.
Usually to prevent high temperature in concrete the coarse and fine aggregates are cooled and even ice cubes are added to the mix.
Cracks are generally treated by epoxy injection or cement grout.
Sir you may correct me
The highest compressive strength achieved is 40.3 MPa, for concrete at 28 days. The concrete's compressive strength decreases as the heating duration increases.
Heat reduces the compressive strength of conceret
When concrete temperature is high then evaporation takes places.if the bleeding is present in concrete then first excess surface water evaporates and particles of concrete shrink and hair crack occurred on the structure.
It hamper the longevity of structure after a long time period structure may be collapse.
How to prevent this type of failure
At first we have to maintain the proper water cement ratio.
If concrete temperature is high then add ice in the concrete.