The Effects of Pouring Concrete in Cold Weather

The Effects of Pouring Concrete in Cold WeatherFirst, let’s define cold weather with respect to concrete. Any time you have 3 consecutive days where the average daily temperature is less than 40°F or if the temperature is lower than 50°F for less than half of any of the 3 days, concrete thinks it’s cold. Pouring concrete in cold weather can have a detrimental affect on concrete curing for several reasons.

Concrete transforms from a liquid to a solid material through a chemical reaction. The speed of the reaction depends upon the temperature of the concrete. When the weather is warm, the reaction proceeds quickly. When it’s cold and the ground hasn’t been thawed, the reaction slows down. That’s the problem: the concrete needs to harden as rapidly as possible to resist pressures caused by water freezing within the concrete.

If the temperature is too cold, the concrete may not have reached a minimum strength of 500 psi soon enough to resist the effects of freezing temperatures. If your concrete isn’t protected with concrete curing blankets after it’s poured, it may cool too rapidly, slowing the chemical reaction.

Poor finishing techniques can also doom your slabs. Freshly poured concrete often bleeds. The water in the mix floats to the top, since it’s the lightest ingredient. Floating or troweling this water into the concrete weakens the top layer. Troweling the concrete too early can seal this bleed water just below the surface as well. If your slab is then exposed to freezing temperatures several days later, this water can freeze and fracture the top layer. Using a concrete curing blanket can eliminate the potential of freezing.

 

Concrete can be successfully poured in cold weather.

Several precautions need to be taken:

  • Be sure to order air-entrained concrete. Request a heated mix or order 100 lbs of extra cement for each cubic yard of concrete. This extra cement helps develop early strength.
  • Be sure the concrete is ordered with a low slump (drier mix). This minimizes bleed water.
  • After the final finish is completed, cover the concrete with a Powerblanket® concrete curing blanket. The heated concrete blankets will prevent freezing and keep the concrete at optimal curing temperature.

 

Learn More

 

 

 

Powerblanket® | The Ultimate Concrete Curing Blanket – The ONLY Concrete Curing Blanket!

COMMENTS (16)
Steelers1fan999@aol.com'
Reply

If you pour cement above 50, and temp. Stays in the 50 s, for 2 consecutive days, then temp. Drops below 32 on the third day are you safe?

    Reply

    Frank, that’s an excellent question.

    Quoting the American Concrete Institute, “Cold-weather concreting, as stated in ACI 306 is, ‘a period when for more than three successive days the average daily air temperature drops below 40 degrees Fahrenheit and stays below 50 degrees Fahrenheit for more than one-half of any 24 hour period.’ This definition can potentially lead to problems with freezing of the concrete at an early age.”

    Please refer to them as the experts here: http://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-construction/cold-weather-concreting

philip.reed04074@gmail.com'
Reply

The footings on our house were poured yesterday at 34 degrees on no frost ground. Temps dropped to 20 degrees last night and the contractor didn’t take any actions to protect the footings from the cold temps. Is there anything that can be done now by me to minimize the damage for night number 2 through X? soils are non-heaving back dune sand. Thanks
Phil

    Reply

    Phil,

    That doesn’t sound like optimal placement conditions. Quoting the American Concrete Institute, “All concrete must be protected from freezing until it has reached a minimum strength of 500 pounds per square inch (psi)… If concrete freezes while it is still fresh or before it has developed sufficient strength to resist the expansive forces associated with the freezing water, ice formation results in the disruption of the cement paste matrix causing an irreparable loss in strength. Early freezing can result in a reduction of up to 50 percent in the ultimate strength.”

    You can read more here: http://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-construction/cold-weather-concreting

ykiki.ks@gmail.com'
Reply

We had a concrete poured in garage this winter and has tiny fractures all over the entire surface now several months later can it be fixed and what do you think caused it

    makeithappenconstructionllc@gmail.com'
    Reply

    The contractor added to much water and over worked the surface with the trolling machine and caused it to to lift mixtures and rocks to surface due to cold temp

leslie.papineau@akwesasne.ca'
Reply

We would like to pour an exterior concrete slab / sidewalk for an entranceway, what would be the maximum cold temperature that a sidewalk can be poured and cured? thanks,

Dlorenz26@gmail.com'
Reply

what is the lowest temperature I can seal the concrete. it is a dyed stamp job. I’m using a stamps here type sealer to give it more shine

csacheson1@gmail.com'
Reply

Have you heard of using antifreeze in the mix of the concrete mix ??

OkieBigen2004@hotmail.com'
Reply

Today the city about 100′ of roadway in front of house, its 33deg now and gonna be in low 20’s or lower by morning and is not suppose to get above freezing for 3 days, am I correct in being concerned?

anilshetty2008@gmail.com'
Reply

Hi sir I am from India and make wet cast pavers using plastic moulds, in winter I find that demoulding pavers is not possible the next day because concrete has not set ,any suggestions

    bricksgraphicdesign@gmail.com'
    Reply

    Hello,

    The exposure of concrete to cold weather will extend the time required for it to reach initial set, which may require finishing crews to be available for a longer period. Depending on the actual ambient temperature, protection of a concrete placement may require the use of windbreaks, enclosures, or supplementary heat. It may also be appropriate to adjust the concrete mixture constituents for the effect of ambient temperature on setting time. This may require an increase in cement content, the use of an accelerating chemical admixture, or both.

    The Powerblanket Concrete Curing blankets could be an efficient and reusable solution for you.
    Cure concrete 2.8 times faster than conventional insulated blankets
    Produce cold weather concreting strength of 3,925 psi in 72 hours
    Maintain moisture throughout hydrating process
    Easily installed and removed

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