Determining the required concrete strength in winter time

The article considers the issue of determining the required strength of monolithic structures in winter, at which they are allowed to be stripped and frozen. The absence of clear requirements for the assessment of the necessary strength in the existing regulatory documents is shown. The comparison of the critical and stripping strengths of concrete is carried out, the influence of the work production time on the choice of the required strength is estimated, and the need to take into account the influence of the temperature difference between the concrete surface and the outside air in the determining of the stripping strength of concrete is shown. The data of calculations, indicating the economic inexpediency of high values of the required strength of concrete and demonstrating an exponential increase of time spent on heat treatment are presented. In the example, an increase in the required strength of concrete by 15 % (from 80 to 95 % of the designed one) leads to an increase in the time spent on heating concrete by 2 times, and with its increase by 20 % (from 80 to 100 % of the designed one) - the time costs increase by 3 times. Conclusions are made about the need for design organizations in the Project section of the organization of construction to indicate the specific values of the required strength of concrete for different structures, while taking into account the economic feasibility.