[TowerTalk] Grouting a New Tower?

[Jim Thomson]

Date: Wed, 14 Dec 2011 15:23:46 -0500 (EST)
From: K7LXC at 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