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I’m just outside of Montreal, Quebec and
was wondering about the pitfalls of pouring a residential foundation in March where the average temperature is
between (low of) -5C and (High of) +3C
Has anyone out there poured in similar conditions??
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I have never poured below zero.
We had an accelorator (calcium- something or other) added to the concete as well as used thermal blankets. The blankets get wrapped around the entire form. In some of the major structural pours we tented the area in plastic and kept the area warm with heaters. A lot of work but sometimes time lines can't be stretched.
You might not be able to pour below zero. For us that was the magic number. "Zero and rising" or we sat in the trailer.
*Use ICFs cover the top of the wall with some sort of insulation. I poured my basement at 32*F snow flurries and got down to about 0* that nite stayed that way the rest of the week. It turned out fine. use ICFs.
*If I did the math right, -5C is only 23F. That's not bad at all. I've poured below that before.Get Calcium in your mix to accelerate the setting, cover exposed concrete with straw or somehting to insulate it and you should be fine.Concrete generates heat as it cures and at only -5C, you shouldn't have a problem.
*If you do pour in cold weather leave the forms on a few extra days and don't start framing until the green is gone. It's easier than you might think to break a footing or wall if you build on it too soon.
*Around here (Wisconsin) we never pour the basement floor until the house is built and we pitch 3-4 feet of Marsh hay into the basement, amd mound it up around the edges. Pitch it out when you start framing the decks. The hay provides protection from the frost going any deeper. Be sure to use hay, not straw.
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Whenever someone speaks of adding calcium to their mix as a winter accelerator, they really mean calcium chloride , actually a salt...which has a good and a bad side to strutural concrete...bad in that chlorides are aggressive agents on rebar and essentially set up a corrosion cell within the concrete. ACI and their Canadian equivalent publish excellent guides for cold weather concreting. Good mixing, using warm water, additional cement, insulation are, IMO, the best insurance for adequate hydration (and leaving insulated formwork on for as long as possible.
*My experience with cold weather concrete is also my only concrete experience. I was contracted to do a whole house remodel and ended up gutting 80% of the structure, including the floor and mudsill beams (could actually tear a 8x10 beam apart by hand due to rot). Anyway, had to do my first foundation ever much later than expected. Started digging in 10 degree weather (warmest) and it got down to -15F at night easily. So, what did I find to be the worst aspect of this cold weather pour? The frost line in the ground. That subzero air spilled into our open pit overnight and froze the ground solid 6 inches deep in one night. Spent the next week leveling the pit with pick axe and shovels because the house prevented the extend-a-hoe from getting at the first days dig area. Did I mention that both neighboring houses are 4' from the house I was renovating? So, get some concrete blankets, cover your dig and heat it if necessary. Same goes for the crete. I used 3500# mix but I understand that 4000# cures faster and has the obvious strength improvement. Concrete does its major "curing" during the second day. Keep the forms in place as long as possible and cover the crete for 7 days (cold weather code requirement up here in Leadville Colorado 10,200 feet guys :). The last thing you want is frozen concrete, I understand that it tends to chip and flake off due to improper curing. God forbid I ever have to pull a foundation!Also, cold weather seems to set the crete faster, at least initiallly. Get those vertical rebars in place fast! Good luck and have fun :)
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I'm just outside of Montreal, Quebec and
was wondering about the pitfalls of pouring a residential foundation in March where the average temperature is
between (low of) -5C and (High of) +3C
Has anyone out there poured in similar conditions??
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Hey damnbrehmer -
Why hay, and not straw ? Around here, Straw is 1/2 to 1/3 the price of hay, and a lot more pleasant to work with.
Also - Can ya give us an easier nickname to work with???