concrete slab

[herr owen]

I'm making a few slabs of concrete. How long after pouring and screeding should one wait before edging and finishing?

[Joseph Meehan]

I take it you have not done this before and you will not have anyone helping you who has.

First question how big are the slabs and how are you getting the concrete?

Note, there is no simple answer to your question since the mix, and temperature cause a lot of variations. It takes a little experience to guess ahead of time and a little experience and judgment to tell when it is ready.

Unless the slabs are very small, I suggest you have it done, or at least find someone who has done it a few times.

[Larry Caldwell]

You don't wait. First you bull float the slab to work up enough mud to finish, and rough edge it to knock the rocks back into the mix. Then you mag float it to catch any irregularities the bull float missed. Then you steel it once real quick to seal the surface and flash it hard, hit it with an edger and either broom it or steel it for a final finish.

If you are going for exposed aggregate, spray sugar water on the surface after the mag float to retard the surface cure, and wait to hose the surface off until the rocks won't move around when you poke the surface with your finger. You can seed the surface with pretty rocks as you bull float if you like.

The only time you end up waiting is in cold weather. In warm weather, you have to move right along or the slab will set up before you get it finished.