Abstract
The most important property of concrete is its strength, especially in compression. Strength depends on the properties of the concrete components, its composition, preparation and hardening conditions. In some structures, concrete grades are established for tensile strength in bending, which depends on the same factors as in compression. To accelerate the hardening of concrete, various methods are used: mechanical, chemical and thermal. Research has been carried out on heliothermal treatment of concrete in a dry, hot climate. The introduction of a superplasticizer allowed reducing W/C and intensifying the initial hardening of concrete at different temperatures. The kinetics of concrete strength growth depends on the activity of cement, W/C and, to a large extent; on temperature and humidity conditions.The increased temperature of the environment by 1.5 increases the strength of concrete, hardened without maintenance, in the first day in comparison with cured concrete. Heliothermally treated concretes with the use of film- forming compositions and translucent heat-sealing coatings at 28 days of age reach the grade strength in a dry hot climate. In the absence of solar radiation during the cold period of the year, the concrete was heated with redundant energy during combined heliothermal treatment. The developed methods of combined heliothermal treatment allow to achieve high strength indicators.