Concrete is a temperature-sensitive material and is most susceptible to frost damage in the first hours or days after casting. The problem of cold-weather concreting is further complicated by two conflicting needs: To protect the concrete surface from drying due to highly evaporative winter conditions; and to make sure the surface is dry when exposed to freezing temperatures.
One way to get the hydration process off to a good start and to reduce the risk of early freezing is to make sure the concrete producer batches and delivers warm concrete. The contractor's cold-weather concreting responsibilities on-site should focus on maintaining the temperature of the concrete within the specified range.
To deal with variable field conditions, the in-place temperature can be monitored hourly using thermocouples placed in the concrete structure. Each one-hour period is multiplied by an age-conversion factor to determine if that hour in the field was worth more or less than an hour in the lab. When concrete has a slower maturation rate in cold weather, field hours are added to compute the maturity of the concrete in terms of equivalent age.