[TowerTalk] Rebar

[Paul Finch]

Hello,

Several years ago, the dam at Possum Kingdom Lake in Texas had a water leak
under the dam.  Long story but the dam was built in the early 20's before
they could conduct complete soil core samples before the construction
process.  Unknowingly they built the dam on several layers of shale.  The
dam did not leak for over 50 years and was not a problem till a housing
development started using dynamite for some construction on the bluffs about
3/4 of a mile south of the dam.  The concussion apparently loosened the
shale, shifting the dam slightly and letting water flow under the dam, in
effect floating the dam with a 3/4 inch crack in it.  Long story longer,
during the repair process they cut 8 foot holes in the 8 foot thick walls of
the hollow dam.  My Father asked them how they cut through the rebar, they
said there was none.  They stated they did not put the rebar in dams because
it would rust and leave voids in the dam and undermine the structure.  The
actual fix of this dam problem is a whole nuther story!!!

I admit that the Possum Kingdom Lake dam is the only one I know about.  I
know that Hoover dam has copper pipe in it to keep it at the correct temp
during the curing process but I don't know if it has rebar.

What about the fiberglass fiber reinforced concrete.  I am about to put a
roof on my 20 x 30 foot tower building and I am going to use lightweight
fiberglass reinforced concrete.

Just something to think about.

Paul Finch
WB5IDM



-----Original Message-----
From: owner-towertalk@contesting.com
[mailto:owner-towertalk@contesting.com]On Behalf Of Bill Coleman
Sent: Monday, June 11, 2001 3:31 PM
To: Mike Gilmer - N2MG; towertalk@contesting.com
Subject: Re: [TowerTalk] Rebar


On 6/4/01 8:06 AM, Mike Gilmer - N2MG at n2mg@contesting.com wrote:

>I read here often that folks recommend that rebar be kept "inside" the
>concrete (and by several inches) - away from the nasty, wet soil in an
>effort to protect it from rust.

Three inches on all sides.

Concrete isn't so porous that water can infiltrate three inches easily.



Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901


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