At what temperature should a concrete blanket be applied?

Question

The weather has been below freezing and it is a debate upon when the concrete blankets should be applied. Just after the brooming or what is your suggestion? Foreman and finisher debate.

Answer 1

My blankets are never made of concrete, that would be very uncomfortable to sleep.

Answer 2

According to guidelines established by ACI Committee 306 (Cold Weather Concreting), for ambient air temperatures between 0 to 32 degrees F, concrete should maintain the following temperatures during curing:

65 degrees F for thin sections
60 for moderate size sections
55 for mass concrete

This can be accomplished by using an insulation blanket, batt insulation, or even by using dry straw. The insulation blanket will help keep the heat produced by the hydration reaction in the concrete. This will be enough to keep the concrete sufficiently warm.

In short, if the ambient temp is below freezing, you should definitely use blankets or some other type of insulation (use isn't optional). If you don't use blankets, you risk having the concrete freeze during the curing period, which will cause the concrete to stop developing strength.

Answer 3

if its too cold the heat of drying in the concrete will be more intense and may cause it to crack as the heat is disipated non uniformly. I would guess the ideal temperature would be 60-75 F. Im sure it would say on the side of a consumer bag.