Publications regarding the first experiments on obtaining accelerated results of the strength of commodity concrete, dates back to 1927-1930. Jerend subjected control samples-cylinders in a saturated steam environment under a pressure of 0.55-0.7 MPa. Patch applied the heating of samples in boiling water within 8 hours. This work, carried out for several years in the construction of the damsha deed (USA), did not then receive further development.
Work on the finding of accelerated methods of determining the strength of concrete were continued in the 50-60s mainly in the direction of thermal processing of control samples. An exception is the method developed in the Department of Highway of Ontario (Canada), according to which control samples are immediately placed in a thermally insulated container for 48 hours. Acceleration of concrete hardening occurs due to heating itself due to cement exothermia.
As the main sources – heat for warming control samples usually used hot water, or steam at normal or increased pressure. There is an experience of heat treatment of samples with hot air.
Concrete hardening modes for various methods of processing control samples are significantly different.
The autoclave method to significantly reduce the duration of the processing of control samples (up to 5 hours), due to a certain complexity, has not become widespread. The development and further studies of the autoclave method can be appropriate for use in automatic systems for regulating strength at especially large concrete plants.
The fundamental drawback of the method of steaming samples for accelerated tests is a sharp decrease in temperature in the chamber when loading it or when unloading samples. Therefore, samples cannot be installed in the string chamber as they are made. The same defect, to a lesser extent, is inherent in the method of warming samples with hot air. In addition, due to the smaller heat transfer coefficient, heating the samples with hot air occurs much more slowly than when processing with steam or hot water.