Pouring concrete in winter

[red61cj5]

Its starting to look like I wont get my floor poured until possibly December, due to monetary constraints. My question is at what temperature range should I call it quits and wait till spring? We don't usually get the real cold (sub zero) temps till after Christmas, so I can still spray it down during the day until then most likely. Its about 1500 sq ft, under roof but no doors in yet so its outside temperature. 4 inches mostly with a 6 inch patch for the lift. Thanks

 

[walrus]

Its starting to look like I wont get my floor poured until possibly December, due to monetary constraints. My question is at what temperature range should I call it quits and wait till spring? We don't usually get the real cold (sub zero) temps till after Christmas, so I can still spray it down during the day until then most likely. Its about 1500 sq ft, under roof but no doors in yet so its outside temperature. 4 inches mostly with a 6 inch patch for the lift. Thanks

Once it goes below 32 it becomes questionable. Insulation blankets, Plastic, ground heaters, or someway to keep it above 32

 

[ForceFed70]

You'll probably be fine, but be prepared to cover with tarps to retain some of the heat from curing. Talk to your supplier about "cold temp mix" or whatever they call it. They can alter the mix to better handle colder temps. Common up here in Canada.

 

[Davefr]

Cool and moist is better then hot and dry. Pick a day where you won't be sub freezing by more then a few degrees. Also ask your concrete supplier, they'll know.

 

[larry4406]

I build houses in northern VA and MD. We build year round. We don't pour unless the forecast is 32F and rising for at least 12 hours. There are admixtures the plant can add to the mix to
improve resistance to freezing and these admixtures are not calcium chloride which is a common field additive and which can corrode reinforcement steel. We also use blankets which are designed to cover and protect concrete.

 

[pstnbly]

If there is frost in the ground or frozen soil DO NOT place concrete on it. The sub base the concrete is to be place must be protected from frost or freeze at all cost.

 

[DougWil]

The general rule is that fresh concrete must be protected from freezing for 5 days.

 

[lakeroadster]

My question is at what temperature range should I call it quits and wait till spring?

I postponed pouring the slab in my barn until spring this year simply because there are to many factors to control.

Here's some data for you:

http://www.concretenetwork.com/cold-weather-concrete/curing.html

 

[Cyberbear]

Simply check with your contractor and with the concrete company they will use for winter concrete pouring. There are additives that will aid in the job coming out as it should.

 

[lh4x4]

As a public works supervisor we poured a lot winter concrete. I forget the additive full name but we used the shortened nick name - posi.

Just be sure that the travel time from the plant is not to long and you have enough help to finish the concrete promptly as it sets up fast.

 

[wssix99]

Its about 1500 sq ft, under roof but no doors in yet so its outside temperature. 4 inches mostly with a 6 inch patch for the lift. Thanks

As others have said above, the ground can't be frozen and you need to keep the temperature of the concrete above freezing. We did this in my house, but we had fully insulated walls and built a platform (hanging off the wall) for a gas-fired heater to pre-heat the space and keep it warm after the pour.

You could tent the space with plastic, but if you aren't insulated, you could end up spending a small fortune to keep the space warm, depending on when the pour happens and how the weather turns out.

 

[Milton Shaw]

If its inside a building, block off the door ways with plastic and put a heater in there. You just need to keep it above 35 or so for a week. Should not be a problem unless you at at altitude and get extra cold from that. Keep it covered and should be ok.

 

[lakeroadster]

Cut and paste this into a Word document. If you can't find a contractor who will agree to it, and sign it.... wait until spring.

The concrete shall only be poured if the ground temperature is above freezing. The concrete shall not be placed on a frozen sub base or frozen concrete forms

Contractor shall take whatever means is necessary to ensure that the concrete does not freeze and shall maintain a surface temperature of 50 F. for the initial 2 days (reference Chapter 7 of ACI 306). Recording devices shall be supplied (placed on the slab - under the insulating blankets) by the contractor and used both inside the barn (minimum of 2) and around the perimeter (one on each side) of the slab to ensure this. Recording device results will be reviewed by the contractor and owner on a twice daily basis. Blankets shall not be removed for 7 days if the temperature forecast shows temperatures below 50 F.

Concrete strength shall be ordered as 4000 PSI. This will be tested by owner after curing 28 days. If testing reveals the strength to be less than 3500 psi contractor agrees to have slab removed and replaced, at contractors expense.

http://www.cemstone.com/userfiles/file/PCA-Cold Weather Concreting.pdf

 

[Orionrising]

are you in a rural area? does a neighbor have manure? it makes a great insulation blanket at least when we build manure pits

 

[matt_i]

I'd get the doors ready, and a vapor barrier for the ceiling.

You might be able to get by with the heated blankets after that, if the environment is more or less sealed from wind.

If backup heat was needed a "jet engine" heater could be used but they put out a ton of condensation that could either start dripping or form icy buildiup on sheathing.

 

[Firebird 1]

I think the coldest we poured a slab was around 25 deg. We had no choice, it was the warmest day of the month. With lots of prep and precautions it came out fine. If you do need blankets a good industrial supplier will have them for rent. Keep in mind though, that in the winter these are in high demand and you may need to reserve some time out.

 

[red61cj5]

thanks to all, I think all things considered, I will just wait till April, there's plenty of things to work on in the meantime. Better safe than sorry

 

[ms fowler]

I built houses for several years in Maryland, and inspected hundreds of commercial building projects. Companies would go under if they couldn't place concrete in the winter. Code requires 34 degrees F and rising. Protect with insulated blankets for a few days after placing--insulated blankets are a common industry practice. Concrete produces heat as part of the curing process. Recent research indicates that even if concrete freezes during the curing process ( think a relatively thin wing wall), when the temperature rises, the concrete will resume curing. I have performed both Windsor probes and compression testing on cores of concrete that froze during the curing process, and that testing confirmed that the concrete still met the design strength.
No recommending that you allow concrete to freeze--especially on a thin slab, but as long as you take simple, standard precautions, it can be, and is regularly, done.