Tips for Pouring Concrete in Cold Weather
Ideally, concrete should cure for 7 days at temperatures between 65-85°F, with humidity levels under 100%. Due to seasonal weather changes, ideal conditions rarely occur naturally.
Use Powerblanket™ Concrete Curing Blankets
Pouring concrete slabs in concrete slabs can be a challenge. The cold temperatures can increase the risk that your concrete will not cure properly. Proper concrete curing is a key to a strong, long-lasting concrete slab.
Never pour concrete on frozen ground. Use powerblanket™ concrete curing blankets to thaw the ground and bring the temperature up to at least 65°F. Why? Not only can the ground freeze the concrete from the bottom up, cracking can occur when the ground thaws. Hollow spots under the concrete may also be created - and driving over the hollow spots will create tension which in turn creates cracks.
Likewise, never pour concrete over snow - you'll simply add unnecessary water to the concrete.
If you're pouring a foundation slab, temperature control is even more critical. A foundation wall is simply a vertical slab - but it's exposed on three sides once the forms are pulled. Foundation forms should be protected with powerblanket™ concrete curing blankets for at least three days, depending on weather conditions.
If you remove forms too quickly, your foundation walls will have less protection, especially if you also remove the powerblanket™ concrete curing blankets. Temperatures below 14°F completely stop the hydration (crystal growing) process.
If the walls are backfilled before proper curing has taken place, the concrete may not be strong enough to withstand the pressure. Once temperatures rise above that point, the chemical reaction resumes, but very slowly. It could take a long time for your foundation walls to gain enough strength to resist the pressure of backfill dirt.
Use Low Slump Concrete
Low slump concrete is hard to work with, but in cold weather it can mean the difference between success and failure. While labor costs can be higher, you'll have less water bleed problems, and you can place the powerblanket™ concrete curing blankets on the slab more quickly, reducing the effects of cold weather.
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