I’m going to prep several “8 X 4′ holes for concrete posts this weekend and am wondering if anyone has advice about whether pouring is even advisable , given the cold wx here in Downeast Maine. What I’ve read seems mostly to apply to more exposed conditions, that is , above ground situations-but I’m wondering if days in the low 40s and nights below freezing can ruin even a simple, below-ground pour?
At a minimum, I plan on using hot tap water (if temps are 40 or below) and covering the columns with tarp and insulation over several days. I’m using some Quikrete ready-mix that was given to me, with sonotubes.
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I can't imagine that being a problem, the ground temperature will be above air temperature for a while. There are additives for cold temperatures, but I don't see the need unless it's constantly below freezing.
thanks MarkH, I'm just going for it!
If the hole is dug in advance you should cover it to retain ground warmth. And insulate after pouring. But if 40F is as cold as it gets you should have no problem -- it's common to pour concrete at zero and below here.
Using heated mix water's not going to help you much. It might kick off the chemical reaction of the portland cement hydrating a bit, but any heat from the water will be mostly dissapated while you're mixing. The reaction to mixing will generate the real heat you need for proper curing. This is what you want to retain as much as possible (during cold weather) while it fully cures. Covering the top of the pour with insulation blankets should be perfectly adequate.
If you really want to have your pour set quickly and avoid freezing issues with inital set, than use Rapid Set concrete mix http://www.rapidset.com. You'll have to work fast with this stuff. For example, flat work is generally ready for traffic in 1 hr! Also, at early stages, the strength of Rapid Set is 10x's greater than ordianry cement.