ABSTRACT
The methods that let concrete harden at a subzero ambient temperature without applied heating can be divided into two groups: use of concretes containing chemical antifreeze admixtures, which can harden at subzero temperatures, and the thermos method that lets placed concrete harden at an zero temperature. Concrete mixed with a solution of an antifreeze admixture continues to harden zero because of the presence of water in the liquid phase. The freezing point of the water is depressed due to reaction with the antifreezer when it is dissolved. Potassium carbonate is a strong antifreezer that accelerates the hardening of concrete at an early age. An antifreeze admixture is selected according to the design temperature at which concrete is supposed to harden. The thermal treatment of antifreezer-containing concrete can produce the stripping strength of the concrete in a very short time.
