Concrete questions?

[Pucman1]

The new space will be poured soon and the nighttime temps have been dipping in the freezing range. Will that cause any issues with the curing of the concrete? What do I need to do to make sure it sets up properly?

 

[thewatusi]

Slab?

If it's enclosed set up some propane heaters. Outside cover it with concrete blankets.

 

[Larryjones]

I doubt your ground is freezing yet. I don't even think you will need to cover it.

 

[ForceFed70]

Concrete releases a fair amount of heat as it cures. Pouring in low temp is actually good for the concrete as it slows the curing process. Slower cure = stronger concrete.

Too cold is indeed a problem tho. How cold are we talking about? A few degrees below freezing is no problem. 10 or more could be tho. From what you describe I think you have nothing to be concerned about and are probably doing this at the best time of year for it.

If you are worried about it - I'd consider covering with tarps/plastic/burlap to help retain some of that heat.

 

[pjboy]

ditto forcefed.

 

[matt_i]

What my slab pourer told me was that we are good to 28F overnight low without any cover. The edges may be more sensitive but mine were basically covered with existing poured stem walls.

I wouldn't think NoVa would get that cold, doesn't it rarely snow there?

 

[DTE]

matt i,
have you researched what temperature range concrete manufacturers recommend? I know there are a lot of post' about troubles with floors but you read very few post' about people curing the floor the way it is recommended or staying within the temp's that are recommended.

 

[Pucman1]

It is getting in the high 20's for the next couple of weeks at a low so that should be ok....it is a slab being poured outside of my existing structure, so outside

 

[DTE]

matt i,
have you researched what temperature range concrete manufacturers recommend? I know there are a lot of post' about troubles with floors but you read very few post' about people curing the floor the way it is recommended or staying within the temp's that are recommended.

My bad, my question was for the op, not matt i.

 

[purplezr2]

Mine was poured with overnight temp of 25 degrees. They blanketed it, it was 64 degrees in the center and about 40 at the outer edges

 

[myredracer]

There are some procedures for placing concrete in cold temps. like http://www.nrmca.org/aboutconcrete/cips/27p.pdf for example. They can add an accelerator and add more concrete to the mix to make it hotter. Do some googling and you'll find some good info. I think the thing that is important is who would be liable if it fails? You don't want to have to replace it all at your cost if it fails (need an agreement with the concrete folks). I would arrange for a test to be done afterwards to ensure it has successfully cured.

 

[Cyberbear]

It was winter when I poured my 30 x 80 monolithic steel reinforced slab with over size footings. The concrete company added a chemical that helps the concrete cure and harden properly in very cold weather, especially after the sun goes down. As most proper curing usually happens within the first 28 days, knowing and preparing for the cold is very important.

 

[padroo]

They can add masonry antifreeze to the mix and that should take it to about 20 degrees. Call your ready mix company and see what they recommend.

 

[Pucman1]

Thanks for all the advise....think I will call to see what the concrete place recommends and then reach out to the contractor//sub and see what the plan is? That way I can make sure we are all on the same page//// Thanks for the quick responses

 

[TommyK]

ACI recommends that a minimum temperature of 55 degrees be maintained for 3 days. Longer is better. You can rent concrete blankets for a week for not a lot of money. Why take a chance?

 

[NUTTSGT]

Thanks for all the advise....think I will call to see what the concrete place recommends and then reach out to the contractor//sub and see what the plan is? That way I can make sure we are all on the same page//// Thanks for the quick responses

If you're having this poured and not doing it yourself/with help, the contractor should have some blankets or atleast access to some if he needs them.

 

[willymakeit]

I would cover immediately after it is finished with blankets. The concrete will push the moisture up as it cures espc. with a vapor barrier underneath. If the top freezes it will spall or pop later,
If you need to work on it during the day uncover it,do your work and recover that night to keep heat in.

 

[Pucman1]

Good news is the garage pour looks like it will happen in the next ten or so days.....unseasonably warm right now so no temps are expected to be below freezing.....I may have nothing to worry about. Thanks again for all the advice.