Date: Wed, 14 Dec 2011 15:23:46 -0500 (EST)
From: K7LXC@aol.com
Subject: Re: [TowerTalk] Grouting a New Tower?
> I recently put up a US Tower HDX-589 crank-up. UST recommends grouting
the
the space between the base plate and the top of the foundation block. I
have purchased the proper non-shrink construction grout and am getting
ready
to do the job. But I'm concerned because I used this stuff to patch my
house foundation before, and it sets up so quickly I'm not sure how much I
should mix up at a time.
I haven't seen any that set up THAT fast. There's plenty of time in my
experience.
You have to mix it pretty stiff so that it doesn't run; e.g. the
consistency of plastic. The fully cured strength looks like over 10 kpsi so
it's
plenty strong enough.
Cheers,
Steve K7LXC
TOWER TECH
## What he used on his house was probably not grout at all, and most likely
hydraulic cement, which will set up in just a few minutes. H-cement works
great
for patching concrete foundations on houses, and is typ 8 ksi.
## as far as relying on grout to provide additional load bearing strength.
Imo, if you
have to rely on grout to provide extra strength, the steel base was never
designed
correctly to begin with. UST sez.... " grout beneath base plate after tower is
installed."
This is on a HDX-689. They don't say if that's the entire underside of the
massive
560 lb, 1" thick steel plate or just the perimeter. The plate is huge, like
52" on a side.
I bought mine used, and the previous owner had used grout just around the
perimeter
of the triangular plate. Grout isn't that strong. It was pretty easy to
remove it. Just
a chisel and hammer. If that was H-cement instead, you would have a helluva
time getting
it out. Grout may well have lot's of compressive strength, but it doesn't
have much
tensile strength.
## If grout is used, you better make sure the tower is perfectly plumb..and
that all the nuts
are tightened correctly. You can't re-level ,or even tighten the top nuts,
once grout is applied...
since you no longer have access to the nuts below the tower !
Later... Jim VE7RF
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