10/31/2021
Concrete gains strength through a hydration process between cement and water curing. Temperature has a significant effect on the compressive behavior of concrete. Don't ever allow your concrete freeze or leave it exposed to temperatures below 28°F within the first 48 hours of placement. Take whatever steps are necessary to protect it from freezing.
When water freezes it expands. Expanding the water molecules in concrete before 50% of its compression strength is achieved could potentially result in its structural failure. The curing process will become suspended and will stall. Freezing water will expand in cement with compression strength below 1500 PSI and leads to aggregate separation and cracking.
Blanketing, tenting and heating, electric blankets, and weather modeling all should be taken into consideration during the colder months of Alpine or cold climate construction projects. Concrete blanket rentals typically run $40 per week per blanket.
When cold weather considerations are made be sure to take a sample of the concrete being poured. Cut a 4" piece of ABS or PVC to 12" deep and pour the concrete being placed into it. Place the core sample in the work area. After 7 days send it to a testing laboratory to verify the engineers specified concrete compression strength to wreck foundation forms is achieved before you pull them down.
Additional samples of concrete can also be taken at the time of pour and can be sent off to an ACI testing laboratory for compression strength verification. If a sample isn't taken during the pour a concrete coring company can be hired to drill a core in the foundation wall. The drilled core can be sent to a laboratory for testing. Core hole will need to be plug with grout. Prior to drilling be sure to reference back to the rebar schedule or drawings. If neither of those are available have a GPRS wall scan performed for rebar before drilling the core.
Cheers!