Introduction to Concrete Techniques and Cooling;
Updated: Jul 8, 2020
Today, high-rise structures, especially hydroelectric power plants, nuclear power plants, bridges and highways, airports, such as the highest level of concrete strength of structures that need to be poured mass concrete and cement-rich high-quality concrete casting is realized. In this case, as a result of the reaction of cement and water, the heat of hydration emerges as an exothermic reaction. For this reason, the temperature in the inner parts of the concrete reaches 80 ° C, while the environment and the differences sometimes exceed 40-50 ° C. When the concrete cools due to the extreme temperature difference between the concrete and the environment due to the rising heat, the volume of the concrete becomes smaller and cracking occurs. Although the concrete strength decreases as a result of these cracks, fresh concrete temperature and protection measures are of great importance especially in the foundation concretes poured in mass, as they will be in contact with water containing harmful substances and chemicals under the soil.
Effects of heat;
During the pouring of fresh concrete in mass, the internal temperature of the concrete at any moment and the temperature differences between the concrete surface and the environment play an important role in the cracking of the concrete. With these cracks that may occur in the concrete, the concrete becomes vulnerable to corrosion, and due to the fact that the concrete becomes exposed to external effects, strength and durability will be weakened and precautions should be taken to prevent the cracking caused by thermal effects.
Factors Affecting Temperature;
Factors affecting the temperature of fresh concrete include the high dosage of cement in the design, the cement used, the aggregate, the temperature of the water, and the extremely hot environment. There are, of course, several ways to minimize these effects. In order to reduce the mixture temperature, it should be worked with cement stock. Silos should be white. Since aggregate is the most used material in the mixture, it is the material that is desired to be cooled the most, but it is one of the materials with the lowest heat transfer rate and temperature control is very difficult. However, there are still cooling methods applied. Spraying enough water to evaporate, keeping in the shade, as well as air cooling in large silos are among the methods applied.
Methods for reducing the temperature of concrete;
The most common method of cooling concrete is, of course, to cool the water added to the concrete mixture. If the cold water does not reach the desired temperature, ice is added to the mixture.
Chiller and ice water units are used for cold water needs. In water cooling with chiller, the water temperature is cooled to 4-8 ° C. In case of a lower temperature requirement, the devices in which the so-called ice-water is cooled to 0.5 ° C are activated.
Flake ice plants are offered as a solution in cases where the ice-water unit alone is insufficient to reduce the temperature of fresh concrete in regions where the ambient temperature is high. With the inclusion of ice in production, the desired mixture temperature is generally achieved.
Before these steps are implemented, you can ask the most accurate recipe from Rosen Cooling System, which has worked as a solution partner in the most important projects of the world in concrete cooling and find solutions to your problems with professional approaches.