The Effects of Pouring Concrete in Cold Weather

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Effects of Pouring Concrete in Cold WeatherEffects of Pouring Concrete in Cold Weather

First, let’s define cold weather with respect to concrete. Any time you have three 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 three days–that is unpleasantly cold for concrete. Pouring concrete in cold weather will have a detrimental affect on concrete curing for several reasons.

How Does Concrete Cure?

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.

Slower Chemical Reactions

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.

Read how Powerblanket solved concrete issues at the Statue of Liberty.

 

Concrete Can Be Successfully Poured in Cold WeatherThe Effects of Pouring Concrete in Cold Weather

Several precautions need to be taken:

  • Never pour concrete on frozen ground, snow, or ice. 
  • 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 concrete curing blanket. The heated concrete blanket will prevent freezing and keep the concrete at an optimal curing temperature.
  • After about three days, remove heated concrete blankets to allow the concrete to air dry.

Powerblanket Concrete Curing Blankets

If you use Powerblanket concrete curing blankets to pour in cold weather, your cement will cure 2.8 times faster than with conventional insulated blankets. Time and convenience are critical factors when planning out a project in the winter, and Powerblanket has you covered.  Our goal is to provide solutions to problems, and give you total temperature control over every process and aspect of your business.

We Solve Problems

From drum and barrel heaters to pipe wraps and snow melting mats, Powerblanket is dedicated to helping your business grow, saving jobs, and improving your bottom line.   Whether you need to extend the pouring season, or you are trying to survive an early winter, know that you have total temperature control with Powerblanket.

Learn More

 

 

 

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

23 thoughts on “The Effects of Pouring Concrete in Cold Weather

  1. 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?

    1. 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

  2. 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

    1. 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

  3. 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

    1. 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

  4. 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,

    1. Hello Leslie,

      It is not recommended that you work with concrete in conditions below 40 degrees F. You also need to consider the freeze/thaw conditions present in your climate. Because of the moisture content in concrete, there can be cracking and size changes if poured in less-than-ideal conditions. We recommend this article for additional information. http://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-construction/cold-weather-concreting

  5. 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

  6. 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?

  7. 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

    1. 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

  8. Hello… When the basement of our new house was poured it was well below the temp requirements mentioned above. they brought in heaters and sealed everything off to counter the cold temperature. as a result when they accessed the basement, they said it was “raining” because the condensation built up on the basement ceiling. of course we didn’t know anything about this and even if we did, we wouldn’t have know this may be a problem. well today, about 18 months later, the top layer of our basement floor is continually crumbling into a fine powder. this of course is unhealthy to breath and makes a tremendous mess. our builder is of course trying to “take care” of things as cheaply as possible. we have been told by a local concrete refinisher there is nothing to do except remove it or have more poured on top. the builder has tried sealing it with an industrial sealer, but there was little to no effect. does anyone have experience with this or have any advice?

    THANKS
    Scott

  9. Hello, can we consider the same requirement for plastering where only for 5 hours during mid night the temperature is -3 Celsius then it becomes 9 during the day.

  10. Good morning
    I to finish a concrete countertop on out door kitchen and the weather is crazy. Today it is 60-37 tomorrow it will be 59-37 Monday 64-46 and Tuesday 72-43 in Oviedo FL
    I’m worried on the effects this will have. I need help 🙏
    Thank you miriam

  11. Hello, we are currently starting a building project since temps are high 30’s sometimes 40’s during the day and 20’s at night the contractor doesnt want to start, this is a pole building and we have covered the building site to try and keep frost out, it does have radiant floor heat would you recommend hooking that up and circulating water before and after the concrete is poured? We can regulate the water temperature so it could be a low temp so the concrete had proper time to cure? Thanks!

  12. I live in the eastern part of Pennsylvania, about an hour and half from Philadelphia. The temps have been in the 30’s-40’s over the past few weeks, but we did see a cold spell in December into early January where temps were 0-20 degrees. The company that we are using to build a concrete pool want to start excavation and then will pour the concrete for the pool. Do you thinks it’s ok for this to happen?

    1. Hello Andrew,
      Talk to the company about any accelerants/enhancers they may be using to speed curing. There are methods out there that allow concrete to be poured in colder conditions. But in the end, temperatures below 50 degrees are too cold for an ideal cure. If you want the best concreting strength, ask to reschedule for a bit later in the year.

  13. Scott R. Just pour over it… It will save you $$ but you will lose ceiling height … I’d suggest at least a 2″ slurry top coat…..

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