In thermal curing heat is applied to the concrete for the purpose of accelerating the gain of early concrete strength. There are several thermal curing methods that can be used, but each method has some specialized properties that make it to be applicable in certain cases only. These methods are
- Hot mix method
- Electrical curing method
- Infrared radiation method
Hot Mix Method
In the hot mix method temperature of fresh concrete is raised up to32 degree centigrade. The elevation in temperature decreases the long term strength of concrete by 10 to 20% than as compared to the normally cured concrete. There are several advantages too i.e., a framework can be removed after several hours of curing.
Temperature of concrete can be increase either by heating the aggregates and water or by injection of steam into the concrete mix. Special care is required in either of the cases especially, the amount of required water for the concrete mix. For this type of curing, special types of frameworks are only used. The framework should be heat insulated.
Electrical Curing Method
There are three most common electrical methods.
- In the first method electrical current passes through the freshly laid concrete between two external fix electrodes. One thing that must be sure is that the electric current should be alternating current. This is so because, the direct current become one of the reasons for the hydrolysis of the cement paste.
- In the second electrical method, a large current is fixed at low voltage. And then it is passed through the steel reinforcement.
- In the third and last electrical curing method, large electric blankets are utilized for the purpose of heating the slab surfaces.
Infrared Radiation Method
It is only used in a very few developed countries. In this method frameworks are heated electrically. This can also be achieved by circulating hot water.