Quote:
Originally Posted by 911Rob
6 mil poly.
3M tape for joints.
Use 15m Rebar at 2' centers, chaired up into the bottom 1/3 of the slab.
After pouring, 24 to 48 hrs, saw cut control joints 10' o/c in top of surface, about an inch deep to control the shrinkage cracks.
Job Done.
Good Luck.
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I do not know the shape of your 500 sf slab, but when you cut the control joints, be sure you make the pattern as square (vs rectanglular) as you can make it. For what ever reason, concrete likes to be square not rectangle shaped. If you look at cracked concrete, you will often see that it is just "squaring itself up".
Also, it is very important the concrete prep of the subsurface. No voids, even surface, and well compacted.
As noted above, you will need rebar to help it stay together (spread the loads). The "chairs" he mentions are little blocks you can get (around here we call the "dobies") that you can tie to the rebar.
They look sort of like this:
They tie to the rebar like this:
When done it will look like this:
It keeps the rebar at the correct elevation. Many folks just drop the rebar grid into the hole, and attempt to pull it up to the correct height. I would say 90+% of the time it sinks back to the bottom where it serves no useful purpose other than cost you money.