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I'm owner-building a house and need to schedule my contractors, materials, and travel, but since nothing can start until the slab is in place, and the slab is weather sensitive, I need to know how to determine when I can schedule the pour.

The house will have a monolithic slab foundation. From my research it appears that concrete should not be poured when the weather will be below 50F during the curing process, and curing can take 72 hours (3 days).

I'm in the northern part of Georgia (US) and the monthly average temperature for February is is highs in the 50's and lows in the 30's. March is highs in the 60's and lows in the 40's. April has highs in the 70's and lows in the 40's. May has highs in the 80's and lows in the 50's.

I'd like to get started as soon as it is safe, but I don't want to use any additives and don't want to risk any low-temperature related foundation problems.

Do I need to wait until May? Can I sneak it in during February if there's a 3-day warm front? Is there an accurate way to know what the weather will be like months in advance? Or do we just set up the forms, have them inspected and ready to go, and watch the weather until there's a three day continuous window over 50 degrees?

  • Can one rent insulating blankets specifically for this purpose? – Jim Stewart Nov 29 '17 at 18:30
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Since you're in Gerogia you might not have this readily available, but in Minnesota we use hydronic heaters and insulated blankets to both thaw frozen ground if needed and to help concrete cure for a few days in below freezing weather. A hydronic heater is a a portable pump that forces heated water through flexible hoses laid over the concrete.

To answer your question, no you won't need to heat curing concrete if the temperature stays above freezing. Just let it cure a few extra days, or wait the full 28 days if you're extremely concerned.

Concrete that cures at a lower temperature is actually stronger after 28 days than concrete that cures at a higher temperature (assuming it doesn't freeze!) Source: Role of Concrete Curing

Figure 2. Effect of Curing Temperature on Compressive Strength

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