Cracks can occur in immature concrete if it is not treated in accordance with the technical requirements established in the project specifications or with the recommendations of a senior engineer with experience in the field.
Cracking in immature concrete can be due to higher internal temperatures, stronger temperature gradients, and greater differences between surface and core temperatures.
Furthermore, it should be noted that an increase in core temperature above a certain value (usually around 70 degrees Celsius) results in delayed ettringite formation. This is a long term effect on concrete. This process increases the internal volume of the concrete and leads to internal cracks in the concrete.
There are several methods to minimize the risk of cracking
- The usual practice is to limit the temperature difference between the outer surface of the concrete and the 20 Celsius core. However, for some projects, this value is left at 25 degrees Celsius, taking into account the size and type of concrete to be used.
- Furthermore, the temperature gradient must not exceed 25 Celsius per linear meter. If construction is done keeping the above points in mind, early cracking in concrete can be minimized.
It should be noted that it is extremely important to follow the recommendations of the model experiment. The thicknesses and types of formwork used for testing the model must also be used for the work.
For thin concrete, following the above instructions is not necessary because the heat of hydration is comparatively less.
However, cracks may appear on concrete surfaces due to insufficient curing. Concrete surfaces should not be exposed to environments where temperature and humidity fluctuate. When the concrete surface is exposed to the environment, the concrete dries out due to the evaporation of water from the concrete, which eventually leads to cracks in the concrete.
In addition, there are several items viz Effects of construction practices on cracking, cracking in concrete, Thermal cracking in concrete , etc. written on this subject.
