Cold Weather Concrete Practices

Cement Definitions

"As reprinted from The American Association for Concrete Construction"

1.	Cold weather practices should start when temperatures are consistently below 40 degrees Fahrenheit.
2.	Use air entraining cement. It’s less likely to be harmed by freezing.
3.	Don’t place concrete on frozen subgrade.
4.	If frost is only a few inches deep, cover the grade with insulating blankets or straw, for 2 to 3 days before pouring concrete.
5.	Take advantage of an accelerator in the mix. Calcium chloride is usually the cheapest, but be sure the specification allows for it.
6.	A non corrosive accelerator may be required. Such as high early strength cement, non-chloride admixtures, or additional cement (about 100 pounds per cubic yard).
7.	Concrete must not freeze for 2 to 3 days, or before attaining a strength of at least 500 psi.
8.	Curing should be at a temperature of 50 degrees Fahrenheit, or more, for continued strength gain.
9.	Outdoor flatwork in freezing temperatures is risky, even when covered with blankets or straw.
10.	Humidity is low in heated enclosures. Apply immediate curing aids to prevent surface drying when pouring concrete within heated areas.
11.	Vent heaters to the outside of heated enclosures. Carbon dioxide on fresh concrete causes dusting.