At 10:04 AM 2/12/2007, Bob Maser wrote:
>I have a 3x3x3 foot concrete foundation in my front lawn that I have been
>using for my HyGain HyTower antenna. MY plan is to remove the HyGain and
>enlarge the foundation to 6x6x4. I have heard that it is possible to hammer
>drill holes in concrete, pour in a 2 part epoxy, and insert threaded rods
>and this will be strong enough to be used for attaching a tower.
It's a little trickier than that, but not much. What you're looking
for are known in the trade as "chemical anchors". There's several
different kinds of adhesives available, depending on what you want to
do. It's not just anyold epoxy.
here's one source: http://www.simpsonanchors.com/catalog/adhesives/index.html
and another: http://www.constructionfixings.com/chemicalanchoring.htm
and from Hilti:
http://www.us.hilti.com/holus/modules/prcat/prca_navigation.jsp?OID=-12136
> I want to
>put up 60 feet of Rohn 65 and have it be self supporting unless a hurricane
>comes through the area, in which case I would put temporary guys on the
>tower. Does anyone have experience with this epoxy method and can give me
>some direction on doing this?
For small installations, your best bet is to buy the kits that have
all the stuff needed. Probably the most common screwup is to forget
to clean the borehole out before putting the adhesive in. Second
most common screwup is to not mix the stuff correctly (either wrong
ratio or not enough mixing or wrong temperature).
Properly done, the concrete will fail before the adhesive does. If
you pull the bolt out, you'll pull out a hunk of concrete with it.
The downside, compared to casting the bolts into the concrete in the
first place is that it costs more to drill a hole and buy the
materials and install it. It typically runs about $4-$5/bolt for the
adhesive, the big expense is the time of the guy doing the drilling
and the rental of the drill. If you were building a subdivision with
500 houses and needed to install thousands of anchors, this would be
a big deal. For half a dozen bolts and the ability to pick the
orientation and placement after the concrete has cured, it's pretty
convenient, especially if you have the right drill.
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