cold wether concreting
cold wether concreting
(OP)
I am looking for strength gain curves for cold weather concreting. In fact we are pouring concrete in cold weather conditions and protect it by heater fans and cover it by tent canvas nearly for 24 hours. After that we leave it open. The weather conditions range from +5C to -15C. In normal conditions the concrete gains 65% strength in one week but what is the situation if it is kept at 30-35C for the first 24 hours and then left uncovered. What are the effects of freeze thaw on this concrete. If you have any recommendations I will be glad to know. Thanks.





RE: cold wether concreting
RE: cold wether concreting
1. The American Concrete Institute (ACI) and the Portland Cement Association (PCI) both have much information on cold weather concreting.
2. You should not let concrete freeze until it has reached it's design strength. Depending on mix design, cement content, cement type, admixtures and curing that can be any where from 3-4 days up to 28 days as Ron has said.
3. When using heaters and fans, it is very important to check CO2 and CO levels, both for worker safety and protection of the concrete. Both gases can damage the surface of fresh concrete causing "dusting" (carbonization). Don't direct the warm air directly onto the concrete.
4. When pouring cold weather concrete we would get an indoor/outdoor thermometer and place the "tail" into the wet concrete, cover the fresh concrete and forms with insulated tarps and leave the thermometer outside the cover. We could then read both the concrete temperture and the air temerture during the curing period. You will find the records very helpful and it is amazing how much heat curing concrete can generate! We've poured heated concrete (the materials were heated in the ready-mix truck) in large spot footings, in +15F weather, on UNFROZEN ground (we had the forms protected) and had the night time temperture drop to -15F after the pour. The concrete didn't drop below +70F for more than 7 days!
Cold weather concreting can be done successfully, BUT it takes planning and attention to details.
RE: cold wether concreting
RE: cold wether concreting