Adding CaCl to Sack-Crete

[Mainiac Mat]

Hi all,

I'm trying to get my last footings in for my screen porch build, but the November weather in Maine is not cooperating with my schedule.... I need to pour two box-formed footings and then two paper tube formed collumns this coming weekend. But the forecast is for mid 50s by day and down to 32 at night.

I had similar weather last weekend, so I tarped the pour at night and three days after pouring the footing was like a mud cake. Fortunately, we then got two days that touched 70 and it hardened up.

So for my next pour, I'm thinking of mixing some CaCl (liquid form that was drained from an old tractor tire) in with the water to speed up the cure. Or... putting a space heater in the hole and tarping it again.

Anyone out there have experience pouring sackcrete in the cold?

Here's a pic of one of the ones I finished two weeks ago when it was still warm for context....

 

[Danno1]

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What about using moving blankets to insulate it at night? I would think that would eb enough at this time of year.

.

 

[PCustoms]

I poured last spring in VT, 2 things I did:

1. Box and small heater above the pier
2. When I bought more bags, I used quick cure concrete at home depot.

I think they also sell an accelerator, but don't quote me.

I bet the ground is still nice and warm, so it's really just the top you're worried about.

 

[Mainiac Mat]

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What about using moving blankets to insulate it at night? I would think that would eb enough at this time of year.

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Blankets (I'm using tarps) will prevent freezing, but they won't raise temp. Everything I'm reading says that Hydration stops at 45 deg. Hydration is an exothermic reaction... but apparently, no reaction, no heat given off.

I poured my second to last footing last night in the dark, as it was 60 deg.

One more footing and then three sonotube piers. Hoping to finish up this weekend.

I poured last spring in VT, 2 things I did:

1. Box and small heater above the pier

I like the box idea...

2. When I bought more bags, I used quick cure concrete at home depot.

I've been looking for CaCl flake... I didn't realize they sold sack concrete with it already mixed in. I'll check it out.

 

[PCustoms]

I like the box idea...

It was simple, I think on one I liked foam scrap around it and used a bucket, the next night was colder so I used a Rubbermaid box and the space heater on low.

I've been looking for CaCl flake... I didn't realize they sold sack concrete with it already mixed in. I'll check it out.

IIRC it's 60lb bags and a bit pricier, but it you have to pour.....

@ConCretin might know how much calcium to add

 

[ConCretin]

You could add some calcium but since you don't really know what came out of that old tractor tire, it would be hard to know how much to use.

I think a safer bet would be to use hot water to mix with and then just cover the forms. If it's in the 50's the concrete will set quicky and generate it's own heat. Ambient temps have to drop a fair bit below freezing before the concrete is in any danger,

 

[haveissues]

ConCretin speaks the truth. I poured about this time of year a couple of years ago and temps hit like 26 or so overnight. It had hot water in it, I covered with blue tarps that night after it set and I checked a few times with an ir thermometer over the next couple of days. It never came close to freezing.

 

[Hank11]

Hot water and then cover them up with a pile of leaves and a tarp.

 

[Mainiac Mat]

Thanks for all the insights.... I got my last footing and pier poured.... I did make a tarp tent with a space heater to jump start the hydration, as it got down to 30 deg. at night.

No CaCl required.