Poured side walk/steps, how long to leave forms?

[Paddy]

Ok. I managed to get a side walk and steps poured Friday. Nice break in temp for it too. How long would you guys wait befor pulling forms? The concrete is of cource hard 24 hr later but,,,,,

Some forms I can remove without putting any stress. Those I will take off today. Others will require a bit a "cats pawl" action or cut a few nails with a Saws-all. I believe concrete obtains 70% strength on 4 days and does not fully cure for 30 days.

I'll have to post some pics of the project, about 4.5 yards of concrete with lots of steps

 

[czechsonofagun]

After a day the concrete is hard enough to walk on.

 

[Paddy]

Czech,

Yes, the concrete has set up enough to walk on. Since I have lots of steps I was hoping to get the forms off to "dress" the area where the treads meet the risers. I cut the step forms to have a 45 deg angle. This allows for you to trowl very tight where tread meets riser. There are a few little turds that would come off easy now but will become perminant if left to long.

 

[czechsonofagun]

I would love to see pictures.

 

[Dusty]

I strip the forms 24 hours later, but am careful not to damage the new concrete. It will still be very soft and with crumble if you put too much force on the edges. Usually concrete will harden withing 30 days to the point where it is considered cured. Full curing to reach its full strength takes longer.
Dusty

 

[EddieWalker]

I take forms off after a few hours and keep working it. It's strong enought to walk on then and threre's no real advantage to waiting any longer. Human weight is so insignificant as to not even matter.

Don't confuse this with vehicle traffic, just human weight.

If the concrete is firm enough to walk on without leaving prints, the forms can come off.

Eddie

 

[Paddy]

Eddie,

I would have replied sooner but...I was taking the forms off! I'm glad I did too. I was carefull not the pry against the new concrete. The reason I was glad was because as stated before, lots of steps. I used 2x8 for my risers and back cut a 45 deg angle to let the trowel get back to the point where the riser meets the tread. I had some help and not all the steps were floated to that precise point. If left a bit over full, the 45 deg angle creates a gutter where the tread and riser meet. In some cases a bit of a lip was left. Taking the forms off early allows for "final" adjustments. Especialy the riser faces.

Thanks to all replied, Photos to come

 

[oscer]

It sounds as though you poured all the steps at once. I poured some recently but was to cheap to buy enough lumber to form them all at once I poured 1 or 2 a day and reused forms. looking forward to the pictures.

 

[Botabill]

Concrete takes about 28 days to cure to a maximum degree. It does continue to cure for many years longer but the 1st 28 days is the most critical period. It is very important to keep the new cement from drying during that period. It's the water in the concrete that allows the cement to burn and cure. It is easier to take the forms off the next day but then you should keep plastic film on the concrete or water it regularly for about a month. Yes it is true that many don't go to this trouble and the concrete may be OK but it will not reach its maximum potential strength and it is more likely to crack. Once concrete is dry it is finished hardening. Cool weather is good for curing as the moisture isn't dried out as quickly as in the heat of the summer however if the concrete freezes the water in it will breakup the bonding points and weaken the concrete.

 

[Paddy]

The side walk was done in two pours. About 7 yards total. I had poured over a brick side walk below but I had used brick that did not hold up to our cold IN winters. The 2x8x4' risers will be saved and are mostly treated lumber.