[TowerTalk] Rebar & Concrete

Robert L. Shohet kq2m@mags.net
Fri, 06 Nov 1998 05:14:04 -0800

Hi guys,

I am getting ready to pour concrete for my Rohn 45 towers bases and guy
anchors and wondered about the necessity of keeping the rebar away from
the dirt?  (Towers to be 100' and 130').

I can't find Dobie blocks or anything else that will allow me to elevate
the rebar.  How crucial is it that the rebar NOT touch the dirt?  I
understand that the rebar will rust but I find it hard to believe that
the structural integrity of the rebar and the concrete "load" will be
compromised so severely if the rebar is dug into the dirt a few inches.

Wouldn't this allow for stronger concrete support by maintaining its
shape since the concrete will not be poured but rather dumped in by a
backhoe? (necessary in my case since a concrete truck can't access the
holes).  Also, how much rebar is necessary in the holes?  Is it really
that important to form a "cage" with rebar and wire?
(Incidentally, my soil is a crappy clay/rock mixture)

I bought a lot of 4' and 2' rebar for the purpose of support but am not
sure on the best way to set it up and don't really know how important it
will be on top of the heavy duty GAC3455 anchors that I am using which
have a solid metal plate about 6" x 4" at the bottom of the anchor.

I would really appreciate your thoughts and comments on this.

Last, how many feet of anchor should be in the concrete and at roughly
what angle should the anchors be sticking out of the hole?  I can't get
a good read on this from the Rohn catalog.  Should the anchor be set at
an angle that will point towards the middle guy, or does this matter?

I only have one chance to do this the "right" way so I want to
overengineer and make the best installation possible.

I will be using 1/4" EHS, GAC3455 anchors (with the equalizer plate
attached) and pouring about 1 1/2 yards concrete (3500 lb mix) into each

Thanks for all your help and interest!

CU for a limited time in SS.  Too much tower preparation work and
chainsawing to do!


Bob KQ2M

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