How long do I let retaining wall concrete set before pulling the forms to expose the aggregate?

Question

I know it will mostly set in 3 days and be at 90% in 7. But do I pull forms before 3 days, or wait longer than 3 days? Everything I can find is about walks and drives- flat surfaces.

Answer 1

10 minutes

Answer 2

it depends on the mix and the pressure on the wall, if for instance you used 6000 psi concrete and the pressure against the wall is 1000 psi then you should be able to remove the forms the next day, however judging by your question you probably don't know any of this so you should wait 28 days until the concrete fully cures.  

Answer 3

I think what you are asking is about the length of time to leave the forms on for the best job? The concern about stripping the forms off too soon is justified. In cold weather the forms should stay on for up to five days to help warmth stay in the concrete as well as moisture. With warm weather the question is again the moisture loss. To slow it down some times the forms will be left on for the three days for the strongest concrete with fewest problems. It sometimes is hard to get the concrete contractor to do this though. They just want to get on to the next job and you can't blame them in a way. These techniques will help but we are talking about a relatively small percentage of ultimate strength that is lost. To illustrate this look at the larger bridge or commercial jobs and you will see the forms stay on for extended periods. Hope this helps.

Answer 4

Are you going to wash off some of the cement for a pebble look?  That you do as soon as the concrete set up enough to support its own weight.  Exact time is hard to tell, depends on the air temperature, and the strength of the concrete.  Concrete cures by chemical reaction, not from drying, it will get warm to touch in warm weather.  Watch it carefully, poke it in out of sight places, and carefully tap the forms before trying to separate.  Good luck  

Answer 5

24 hours is enough for the concrete to set...it keeps getting harder over time,,cures in around 7 days....depending on the application,,(load placed against the wall) i would wait the week before the back fill...if it is not retaining any weight its ready to paint or whatever after the 24 hours

Answer 6

You could pull them the next day, ask the guys that done the pour, they would know what mix they brought you.

Answer 7

It depends upon what you are doing.  A wall that is not under any other pressure will easily stand by itself in 24 hours under normal conditions.  

Last week however I made some "concrete" sills for windows and a small wall in front of one window.  Although I started with a commercial mortar mix I added quite a bit of sand and portland.  I finsihed the surface and was observing the hardening of the 4" thick wall in front of one window.  When the hardness was just about good enough for me to finish the surface I removed the forms.  The reason for this was that in addition to tapping the form to get a smooth surface on the sides I wanted to trowl the sides.  The 6" high wall was still soft enough to steel trowl but hard enough to hold its shape.   Now if instead of a 6" high wall I had a 12' high wall that I was working with I might wait a little longer 3 to 4 days.  

But your question spoke of "exposing the aggregate."  Tapping the form while the concrete is wet will push the aggregate away from the form for a smoother finish.  If you are looking for a particular finish you may have to adjust your form removal time accordingly.  After 24 hours the concrete will be ridged but you will still be able to "brick" the surface to remove portions you don't want or dig out needed holes.  If you want to wash the surface to expose the aggregate on the sides your time has to be a little more careful.  Three days is too much.  Again depending upon weather less than 24 hours should be the best.  

I would not back fill for over a week.

Answer 8

I would obviously try the search engine and the forums, but if you don't find an answer then I can suggest you to ask da Gurus.

I am not much of an expert in this field but I have asked similar questions in the past to da Gurus and inevitably received an answer from the experts for 5-to-10 bucks.

http://www.dagur.us/welcome.php