Freezing concrete

[kfc510]

Is there a good info resource on acceptable curing times before freezing for concrete?

I poured some piers in Philo, Mendocino a couple of days before it dropped into the 20's at night, and I've got a few more to do. I have never really had to worry about concrete freezing before, but it may be an issue with the next set. (And for all I know, it was an issue with the first set, though I doubt it.

Clients are also learning some lessons- pipes froze at their vacation home. Unusually cold here recently.

Thanks,
kevin

[Allan Edwards]

Re: Freezing concrete

If these are in-ground piers and you poured when temperatures were 40 or above, I would not worry.

[Scott Jameson]

Re: Freezing concrete

If piers are cast in the earth, cover concrete & two foot perimeter with straw, top with poly & secured against wind.
<http://www.engr.nmsu.edu/13_concrete/kane.pdf>

[m beezo]

Re: Freezing concrete

wish my brother would get on board just for these types of discussions.
He pours concrete just about year round in Colorado. What I have picked up from him and from my own pouring during cold weather is pretty much what Allan and Scott said. The ground stays warm for quite a while so you have some warmth there. The concrete makes it's own heat so that helps. Covering and tarping helps trap that heat while it dries. Think insulating blankets that get laid out on sidewalks and roads to hold in the heat.

Other thing is there is a formula for adding a drying agent to the concrete. Around here it is often refered to as Alum and is often used as an accelerator in plaster and concrete. Mine comes in a dried flake form. I think my brother talks about calcium chloride but would be best to check with a concrete guy or company in your area.

[kfc510]

Re: Freezing concrete

If these are in-ground piers and you poured when temperatures were 40 or above, I would not worry.

Temp was 60+ for the first set when poured, 40's at night for two nights then into 20's at night.

At what point does one start worrying? I mean, I'd think that the curing heat of the mix would be keep things above freezing even if it dropped to 30 degrees that night.

If you poured in the 40's and knew it was going to be high 20's that night, would you even bother with blankets/hay/etc? Or does it need to be low 20's or lower before it's an issue (piers in ground, 8-10" above grade in tubes with column bases set in)

Thanks,
kevin

[MarkMc]

Re: Freezing concrete

Many variables see ACI 306 {starter}. That 40° to 25° air is different when the soil temp is 55° in the fall than 40° in spring.

[Allan Edwards]

Re: Freezing concrete

Temp was 60+ for the first set when poured, 40's at night for two nights then into 20's at night.

At what point does one start worrying? I mean, I'd think that the curing heat of the mix would be keep things above freezing even if it dropped to 30 degrees that night.

If you poured in the 40's and knew it was going to be high 20's that night, would you even bother with blankets/hay/etc? Or does it need to be low 20's or lower before it's an issue (piers in ground, 8-10" above grade in tubes with column bases set in)

Thanks,
kevin

Of course we do not have a lot of cold weather pours, rule of thumb here for a slab is we want temperature to be 45 and rising, if it is 45 and dropping we do not pour. I'm sure there are additives that can help if temp is below 45. For piers in the ground I would be less worried, I personally wouldn't worry unless it was freezing when I poured them. A good local engineer or Geotech person or even redi-mix company should be able to advise you.

[kfc510]

Re: Freezing concrete

Many variables see ACI 306 {starter}. That 40° to 25° air is different when the soil temp is 55° in the fall than 40° in spring.

Cool link, thanks.

[kfc510]

Re: Freezing concrete

Of course we do not have a lot of cold weather pours, rule of thumb here for a slab is we want temperature to be 45 and rising, if it is 45 and dropping we do not pour. I'm sure there are additives that can help if temp is below 45. For piers in the ground I would be less worried, I personally wouldn't worry unless it was freezing when I poured them. A good local engineer or Geotech person or even redi-mix company should be able to advise you.

Unfortunately I don't know any engineers or batch plants in that area, although I could probably look one up and see where a phone call gets me. (edit to add: we're mixing on site, so I haven't contacted any concrete companies).

Philo's pretty far outside my normal range. In my normal area directly near the bay it's essentially a non-issue, so I've never studied it before.

Thanks again to everyone for the replies.

[rvpinc]

Re: Freezing concrete

Kevin,
You could call in a local for some help....(That is meant as lighthearted...I have also gone down to the Bay Area as of late to work)

You probably do not have a problem. Given the temps you during those days (almost the same as here on the coast) and with the mix on site, the concrete not travelling from Ukiah, you are, from my history, just fine. Though all the information above is good to have, especially if it is going to be a bigger pour or a slab.
As a Public Works Inspector in Milwaukee for a awhile we had very strict parameters about pouring in cold weather. Contractors were allowed to pour down to (and below)freezing using the right mix, timeliness of the pour and, yep, warm water! I oversaw a state route pour through the city of 9 sack mix where the temps were expected to drop to 28f and with the batch plant three blocks away and the admixes that road was beautiful.
Have a great time while you are here and don't be afraid to call a local for advice. The guys over at Nor-Cal Concrete in Ukiah are very friendly...us guys on the coast, not so much. It's the salt air that makes us crabby!

[kfc510]

Re: Freezing concrete

Kevin,
You could call in a local for some help....(That is meant as lighthearted...I have also gone down to the Bay Area as of late to work)

You probably do not have a problem. Given the temps you during those days (almost the same as here on the coast) and with the mix on site, the concrete not travelling from Ukiah, you are, from my history, just fine.

Heh, damn migrant workers... I'd call for help but it's just a 12x18 arbor. They actually had a local who was going to do the job, but he became unavailable around harvest time, and they asked me to step in.

The first 6 piers I did 2 weeks ago are fine, and it says 60's/40's for the next few days, so I can pour the last 3 with no worry today.

That was quite a cold snap by our standards though.
kevin