when to remove concrete forms

[ratface]

Yesterday I poured two small post piers 12X12 inches by six inches high, I coated
the 2x6 wood forms with spray PAM. I can either remove them in the next two days
or else I have to leave them in place for several weeks until I get back to them.
I used bag concrete mix. The temperatures here are forecast in the 70's for the
next two days and then steady 50's, I think we had a slight frost last night. They
are under a barn so protected from rain. Which is better to limit any damage to
the concrete and to make removal go smoothly? Now or later?

 

[Russ from MN]

I would leave them on for the several weeks option. The slower the concrete cures the better it will be.

 

[Red Dave]

It won't make any difference to the concrete as it will cure with or without the forms.
But leaving the forms on will protect the concrete from damage while it is still green.

 

[4wdtom]

Keeping the concrete wet/damp will increase the strength by slowing the cure. The longer the better.

 

[Blackhole49]

We used to pour in the morning and begin stripping forms in the afternoon. I would pull them before you left. Either way, it won't hurt the cement.

 

[MSD]

They will probably come off easier while green than letting them on till it is cured. Most of the concrete guys I have worked with would pour in the morning and take forms down that afternoon. Course they needed them for the next days pour usually.

 

[1948CaseVAI]

Do whatever is convenient - it will not matter. The guys pouring the freeway a mile from me do not use forms at all. Thier Gomaco is a slip form rig that crawl along and the forms go with it. The roadway isn't supported by side forms for more than a few minutes. Works slick.

 

[BarnyardEngineering]

The concrete that's going into those roads is extremely stiff when it's poured, so dry it barely would barely come out of a ready mix truck.

 

[ratface]

It seems that the consensus is that at the end of the day the curing won't be affected enough to matter. They really are just keeping a support post from contacting the ground. I have never removed forms, do they come off rather easily regardless of time in contact with cement or does it get more adhered as it remains?

 

[MeanGene1]

If you want to see concrete guys come unglued, turn on a vibratory roller close to freshly slipformed curb & gutter- the mud will flatten right out. I saw an apprentice do it a few years ago- luckily for him, it's hard to fire an apprentice, you're not supposed to know anything lol

 

[Dusty MI]

They are rebuilding I-496. And I see they have a concrete mixer set up on site, and they are dumping it into pay-loaders which are hauling it to the area being poured.

Dusty

 

[Russ from MN]

If you oiled them they should come off easy anytime.

 

[Centerplate]

Most concrete guys take them off the next day.

Highways use a nine bag mix for their concrete.

 

[Stephen Newell]

I would wait until it turns white to remove the forms. Rush it and you could have chunks break off.

 

[Scott 730]

Don't overthink this. The forms are only 1 foot square. The forms are not going to stick. It's not like you are trying to strip a gang form from an elevator shaft wall. :roll:

 

[dpendzic]

keeping damp wet will increase the cure as the chemical reaction needs moisture---usually one day cure time is enough to strip forms

 

[Hoenes]

Hats off to a brother that knows what a gang form is !

 

[1948CaseVAI]

(quoted from post at 10:23:30 10/13/20) The concrete that's going into those roads is extremely stiff when it's poured, so dry it barely would barely come out of a ready mix truck.

I guess I had assumed he didn't have a too-wet slump. We have always removed forms at the end of the day if we poured in the morning for driveways and sidewalks. Of course he cannot put a load on it at that time as it will break easily, but he can strip the form to use elsewhere.

I visited a girl in Georgetown KY who had a new house and they never did remove the forms. She thought they were required to stay...

 

[da.bees]

For what it's worth in knowing,the concrete will still be curing next year,actually in over 10 years but it's ok to remove forms the following day or next month.