Date: Fri, 16 Dec 2011 21:09:04 -0800
From: "Jim Thomson" <firstname.lastname@example.org>
Subject: [TowerTalk] To: <email@example.com>
Grouting a New Tower?
Date: Wed, 14 Dec 2011 15:23:46 -0500 (EST)
Subject: Re: [TowerTalk] Grouting a New Tower?
> I recently put up a US Tower HDX-589 crank-up. UST recommends grouting
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
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
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
plenty strong enough.
## 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
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
correctly to begin with. UST sez.... " grout beneath base plate after tower is
This is on a HDX-689. They don't say if that's the entire underside of the
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
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
it out. Grout may well have lot's of compressive strength, but it doesn't
## 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
&&&& As a side note, the entire weight of a HDX-689 is applied to the 560 lb
at 3 x attachment points. Each attachment point consist of a vertical steel
riser, made from
1/2" thick angle steel, welded to the 1" thick steel base plate. Right below
the riser's is
where the 4 x 1.125" anchor bolts are. IE: the weight of the tower is
split into 3.
Hence the 12 x anchor bolts, 4 per group. the only place where grout, or
anything else would
provide extra support is in the area surrounding each group of 4 x anchor
bolts. Placing grout
around the entire perimeter won't provide any additional load bearing
capacity. It's an aesthetic
Later... Jim VE7RF
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