Date: Wed, 22 Sep 2010 17:01:50 -0400
From: Roger <roger@rogerhalstead.com>
Subject: Re: [TowerTalk] Re-bar Cage - welding ??
If you look at the construction of most rebar cages it appears the cage
does little. It's the individual sections of rebar, their shape, and
overlap. IOW the cage is there to keep the concrete from losing
structural integrity.
## Concrete has loads of compression strength, but very little tensile strength.
[stretching]. Wood has more tensile strength than concrete, so does plastic.
The re-bar is to improve the tensile strength. Pour some concrete, and
form it into a 12" square, x 5/8" thick. Wait a month, then smack it with a
hammer,
and watch it explode. The stuff has no strength. If they didn't put re-bar in
floors
in high rise buildings/condo's, the floors would collapse under their own
weight.
## Line a tower base with concrete on all 4 x sides, + the top, and it's
now one homogenous block of cement.
I've welded quite a bit of rebar, but it was in uses where strength was
not paramount. "so far" I've never run into a problem with the welding,
but as has been stated the content of all but given specifications is
uncontrolled. It could be easy to come up with some alloys that would
end up with crystalline welds containing very little strength.
## if u used 60 ksi weldable re-bar, you won't have a problem. The stuff
is relatively cheap.
Jim VE7RF
73
Roger (K8RI)
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