On Thu, 17 Feb 2005 22:24:25 GMT, Ecnerwal
wrote:

"SteveF" wrote:
If I put in radiant piping I must but in either mesh or rebar to hold the
piping in place during the pour. From what I've read on the concrete web
sites, the rebar shouldn't cross the control joints since that defeats the
purpose of the control joint. I guess the radiant piping can stretch a
little without a problem.

How did you handle the control joints or did you just leave them out?

Don't know where you're reading that, but I've never seen that one, and
I've been known to read concrete books for fun. In any case, it does not
match up with practice, as I've seen it, and built it. My floor is
sawcut ~1 inch deep on a roughly 11 foot grid, rebar & mesh is
continous. The cuts were filled with caulk before the floor was painted,
which keeps crap from collecting in them. The cuts serve to concentrate
any cracking stresses into cracking along the cut. The rebar keeps the
cracked chunks from shifting WRT each other. If you cut the rebar, the
various hunks of floor will most likely offset significantly over time,
making it very hard to move stuff around the floor, and also breaking
your tubing.

You may be thinking of an expansion joint, which needs to be free to
move, but is rarely encountered in home or home-shop scale projects,
most of which are not large enough to need them.
I had a floor poured about seven years ago. It is seven inches thick
at the thinnest. It has re-bar, wire mesh, and that fiber that you can
have added to concrete. The only cracks I got were after an earthquake
that moved machines weighing 1 and 3 tons. And, when I let a 2.5 ton
machine down too fast, I got a crack from that. All the cracks are too
narrow to get anything in, like dirt or chips. But I was wondering if
there was some epoxy or other glue that could be drawn in by capillary
action to keep the cracks from getting wider. Or even if it needs to
be done. There are other places where I've chipped the floor pretty
deep, like when using a crowbar to shift a machine when the slab was
too soft. Epoxy is used to fill these and works well.
ERS