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[TowerTalk] concrete expansion anchors and epoxy

To: "TowerTalk List" <>
Subject: [TowerTalk] concrete expansion anchors and epoxy
From: "FireBrick" <>
Reply-to: FireBrick <>
Date: Mon, 10 Nov 2003 13:33:08 -0600
List-post: <>
In my business as a masonry restoration contractor, I used many types of
anchor systems.
I also use many types of epoxies.

The anchors I liked best and were specified by the engineers were made by
For a tower base, you would want as long an anchor as possible, and
obviously, a diameter similar to the specified J bolt size.

Reason for wanting as long an anchor as possible is to have as much concrete
mass above/around the bolt.

As for the epoxies, I've used two basic types, Hi-Mod and Lo-Mod. The
Modulus refers to its flowing or clumpiness.
Sika is the brand I used most. Comes in two parts.
Also comes in both Modulus types.

If you drill a hole into concrete, and wish to smear the epoxy around the
expansion bolt, they you want a epoxy that does not flow or drip. This type
comes in two cans, you mix the appropriate proportions, allow to sit for the
instructed amount and then basically glob the epoxy onto the expansion bolt.
The other type of epoxy frequently comes in a caulking gun type tube that
has both activator and product in the same tube but separated by a thin foil
You mix this type in that tube by pushing the attached plunger back and
forth the instructed number of times.
The bolt gets inserted into the concrete, and then you use the plunger to
drip the epoxy into the hole and let it seep down around the expansion bolt.

Each Mod has it's advantageous and disadvantages. The glumpy type (glumpy is
a technical term <wink>_can be mixed to the desired amount. The drippy type
is either used all at once or throw the rest away.

Now as for purchasing...I bought my supplies from a firm that specialized in
caulking and epoxies.
Hilti has it's version (read higher priced) and is sold at special Hilti
stands in selected Home Depots.
Check your Yellow Pages for locations near you.

I never trusted using simple threaded rod and epoxy in the type of work I
did, securing large sections of stone to Chicago Landmarked building. I only
used expansion bolts.
Hardware store threaded rod is of unknown strength. I would not use it on my
own tower.
Expansion bolts come with a engineering spec sheet.

All that being said...I have no relationship with the products/brands
mentioned above, just years of experience.
If I was to anchor a tower base to an existing concrete base, I would use
this system.

I'm a internaut and I'm OK. I surf all night and I sleep all day.

Bill H. in Chicagoland


See:  for "Self Supporting Towers", "Wireless Weather 
Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
and ask for Sherman, W2FLA.

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