pouring cement in winter

[PineRidge]

4 years ago in Jan. the builder mixed calcium chloride in the concrete for the basement and garage floors when building our home. A year later they spiderweb cracked. Not real bad, but I would wait if I had it to do all over again.

 

[Junkman]

I would also suggest that you wait till around June when the ground has sufficiently warmed and the moisture is mostly out of it.... this is the best time to pour concrete. Make your appointment with the contractor now for then. Most of them schedule work long in advance.

 

[bebster]

To quote from an article on this subject: "Calcium chloride is not an antifreeze agent. When used in allowable amounts, it will not reduce the freezing point of concrete by more than a few degrees. Attempts to protect concrete from freezing by this method are foolhardy." Article on Calcium Chloride

"Calcium chloride should not be used where reinforcing steel is present. "
Another Article

I'm inclined to agree with most of the posts here that it is better to wait until the chance of freezing is minimized, assuming your schedule permits. The risks and costs of trying to pour and cure concrete during the freezing winter months might not be worth it.

 

[gordon]

Ask if high early is avaliable in your area. It's concrete with a #5 portland instead of #1 portland. It's ground finer for more moisture contact and hardens much quicker.

Sill needs to be covered with blankets in real cold temps.

Good luck
Gordon

 

[jmc]

Thanks all, for the good information. Its a tough call but my impatience won. We pour tomorrow. The contractor says if we cover it with straw/visqueen (sp?), and since its inside a shell, we'll be ok without additives. Got a salamander heater lined up as a backup plan.

 

[Junkman]

consider putting 6 mil plastic under the floor to keep the dampness down in the summer months..... if the contractor says that will keep it from drying fast enough, you can put some slits into the plastic to allow the water to drain through and it will not hurt the plastic barrier from doing its job later on. This is how one of my cellar floors was done and it works great....

 

[em14]

I would not slit the moisture barrier instead try to maintain it's integrity. Moisture will find that slit and you may have a moisiture problem in the future. The concrete should be placed with as stiff a mixture as you need to maintain the proper "slump". It will dry all in good time and your contractor knows that. Don't rush it and spoil it ... The contractor will be long gone and your money spend when the concrete fails. I also would not pour concrete in freezing weather unless I could heat it. Just for what it's worth ...
Leo

 

[RonL]

Junkman

Concrete sets by chemical reaction, not by drying. If concrete dries out before it has properly set it will result in a weaker concrete. Plastic moisture barrier on grade keeps moisture from intruding after the building is finished, but it also keeps moisture from leaching out before the concrete has set properly. It also serves as a radion barrier when it is properly installed.

RonL

 

[Junkman]

Leo:
Just for what it's worth....... I couldn't disagree more! I have a few slits in the plastic in my garage floor and there is no perceivable moisture coming up from the floor. I was not recommending that it be sliced and diced, but rather one or two for every 100 square feet. I will agree with you not to pour concrete in freezing weather and I have already said so.
RonL:
I know that concrete sets by chemical action, but the liquid, more commonly known as water has to evaporate also. The small amount of water that pools at the bottom of the pour would normally be absorbed by the dry ground that the slab was poured on if no plastic were used no matter what time of the year it is poured. As for this causing a problem, I sincerely doubt that is the case, because bigger projects than this one are routinely poured without the benefit of plastic barrier, such as footing for foundations, bridge abutments, etc.

Disclaimer: This is not a flame or a battle ground, but just a different opinion between 3 people with a divergence of opinion on the subject matter.... /forums/images/graemlins/smirk.gif I respectfully submit that we can agree to disagree and that the opinion of one might not necessarily be the correct one..... /forums/images/graemlins/grin.gif

 

[em14]

Beleive me I'm glad that your basement has no moisture problem. However, I would not wait for the moisture in concrete to exit such a small slit as you suggest cut. I would think that the majority of the water in your basement concrete left the concrete via evaturation as in the normal curing process or you had a very dry base and a number of slits and I hope that you never had a mositure problem to begin with. Anyway I stand by my previous and we can just disagree! I would suggest that anyone pouring concrete research the local concrete plants and local inspectors before undertaking a large pour.
Leo