Q.: How can we make concrete set up in cold weather?

A.: The general recommendations for cold weather concreting make provisions for (1) heating the concrete so that it is at least 50 degrees F'4 when it arrives at the jobsite, and (2) protecting it against subsequent exposure to freezing temperatures, keeping the concrete above 50 degrees F during the ensuing period when it is being finished and cured. Your question, however, probably refers primarily to the prolonged period that frequently elapses between bull-floating and finishing. Anything that can be done to increase the temperature will help: using heated concrete, preheating the subbase or subgrade or preventing it from getting cold in the first place, enclosing the work space, using an accelerator in the concrete, using Type III cement, using a higher cement content and reducing the water content while keeping the same slump.