experts needed!

[gearhead204]

Ok guys any of you cold weather mud guys? looking to pour a slap in the new shop on Monday but the weather is forecasted to turn cool to say the least, Thursday high 24-26 lows around 15 I have the shop enclosed on 3 sides and tonight i put a tarp on the other to close it in. I have enough concrete blankets to cover the slab, my question is how warm do I need to keep the building? 35ish or so ? the mix will be 6 sack with hot water and I may add 1% high early...........any thoughts

[carlotpilot]

if you can keep temp above 32 you should be ok with cal added

[gearhead204]

thanks, I have a few 300,000 btu propane heaters I can use, but I really don't want to screw up a 30yd. pour, but I don't want to wait 2 weeks and hope the weather mellows out either!

[mrsmackpaul]

cant concrete be poured in the cold ?????? most likely a dumb question I know but I have never lived anywhere that gets as cold as does over there does the concrete freeze before it sets or something

Paul

[masterwelder]

If you have enough blankets to cover the entire slab you will be ok. As long as the ground your pouring on isn't froze allready.

Concrete creates it own heat as it cures. If you can throw heat in the building besides that's not going to hurt.

The question is who gets to put the finish on it in freezing cold?!

[farmer52]

I would talk to the concrete supplier. I believe they put "anti-freeze" in the mix to pour in freezing temperatures.

[gearhead204]

yes concrete can be poured in the cold, but if the water in the concrete freezes before it evaporates, it will cause the surface to scale off.

If you have enough blankets to cover the entire slab you will be ok. As long as the ground your pouring on isn't froze allready.
Concrete creates it own heat as it cures. If you can throw heat in the building besides that's not going to hurt.

The question is who gets to put the finish on it in freezing cold?!

the ground under the slab isn't froze. I didn't mention but I also put that tekfoil bubble wrap under the slab, so that should also help to protect the slab.

I would talk to the concrete supplier. I believe they put "anti-freeze" in the mix to pour in freezing temperatures.

Ken I haven't heard of this, only the anti-freeze to put into the finish power trowel operator! But I will check on it.

cant concrete be poured in the cold ?????? most likely a dumb question I know but I have never lived anywhere that gets as cold as does over there does the concrete freeze before it sets or something

Paul

[gearhead204]

don,t know what I did wrong but mrsmackpaul your response is on top of the last page.

[Vladislav]

Locally people cast concrete structures all over a year.

When temperature goes lower than the freezing point concrete suppliers add anti-freeze additive.

I asked several times and was told from them if I spread concrete at about 3-5 degrees below zero Celsias (freezing point) I might need no additive, just put a poliethilene film onto. Concrete hardening reaction radiate heat and it would be enough just to cover it over. It was said to the case I drop outside, not inside the building. Done it many times myself.

[1958 F.W.D.]

What the hell? What am I, chopped liver? You can't call the building inspector/Waterous Pump Expert/Detroit Diesel Closet-comer-outter who's number you have in your cell phone??

Ok here's the deal with cold weather concrete: (as far as a building inspector is concerned....but what we say, *usually* gets you a good quality and code-compliant product in the end....)

1. The slab prep MUST be kept warm prior to the pour. No sense pouring concrete (even if it was made with hot water) onto a slab of ground covered with frost (hence it is below freezing and will freeze the water in the concrete soon enough....) You should prep the area, keep it heated with heaters if you have to and keep it covered with the concrete blankets for at least 2-3 days prior to the pour- this will get warm the ground to enough of a depth suitable for pouring.

2. The minimum early cure time for concrete with no additives is 5 days. If the concrete has no additives or anti-freeze, you MUST keep it heated and blanketed for a minumum of 5 days.

3. If you will be having an additive such as 2%Polarset or another non-chloride chemical (cannot have any calcium or chloride based additives in concrete that will encase rebar or WWM as it will eat it away...) is three days.

Here's what I would do.....If you have not done the final "dig" of the slab area, schedule the concrete for the last possible delivery time on the day......Wake up early that day, and do your final dig (several inches....) Keeping the area covered with the earth will help you to retain the natural warmth of the earth. Do the final dig, then lay out the stone and tamp it, then the WWM, the rebar and the vapor barrier. If you have a few hours until the deliver, cover that shit with the blankets. Then after the pour and your smoothing, cover that shit again ASAP.....If its gonna be THAT cold I would double up the blankets or even cover the blankets with 4 or 5 inches of straw. Then light up a propane heater or two and make sure that shop is as weathertight as possible.

For temps that cold at night I would go with no less than 2% Polarset or an equal product. Early high and I forget what the slump should be....I have a copy of ACI 318 (the concrete building codes) out in my truck but I dont like the things you said about me coming out of the detroit closet to walk out there to get it.....)

I assume there is no such things as building permits or inspections out there.....What slab thickness? 8" with #4 bars 24" OCEW???? 6" WWM???

[1958 F.W.D.]

I would talk to the concrete supplier. I believe they put "anti-freeze" in the mix to pour in freezing temperatures.

Ken normally they would only use hot water in cold weather. Any additives cost extra so you would have to specify (and pay of course!)