"Matt Whiting" wrote
Interesting as I've never seen an interstate concrete highway that used
rebar... The only metal in most highways is the row of pins used to lock
the sections together at the expansion joints.

The type of concrete highway design varies from un-reinforced slabs with
doweled joints, to rebar reinforced slabs with doweled joints, to welded
wire mesh with doweled joints, to continuous slab reinforced with welded
wire mesh or rebar, or continuous rebar and welded wire mesh.

I have seen older concrete torn up in Columbus Ohio, with tons of rebar, and
recycled into new concrete. I have seen welded wire mesh placed too close
to the surface, and the top layers of concrete worn or spalled (cracked and
flaking) off, and the wire visible.

How the concrete roads were constructed varies partly by region and design
needs, (like cold) and partly by what was thought to be the best method, at
the time.

I suspect that what was seen by the earlier poster was 6 x 6 inch welded
wire mesh. Rebar (in sizes from 5/8" and up) should be placed much deeper
in the pour, and usually stays put, whereas the mesh can easily be misplaced
too close to the surface.

I will not discount the studs and chains accelerating the breakdown of the
concrete, but wire mesh being exposed is in large part due to other forces
breaking down the concrete, and improper mesh placement.

Just my opinions and observations.
--
Jim in NC