used improper usenet message composition style
by unnecessarily full-quoting:

When rebar is used, how do they keep it IN the concrete, so it's
not laying right on the ground?

Rebar Chairs:

http://www.quadlock.com/images/icf_c...bar_Chairs.png

http://www.concreteconstruction.net/...m45-984353.jpg

http://i00.i.aliimg.com/photo/v0/222...ebar_Chair.jpg

As far as mesh, the seems like it would be much harder to keep
off the ground.

Any of those re-bar chairs could also be used for wire mesh.