[TowerTalk] Epoxied bolts

[Thin Air Communications]

Mark,

I know a lot of people who do use epoxied bolts. I have seen the use of
epoxied bolts on concrete tilt-up buildings on the floor to wall joints, but
only with a significant steel reinforcement channel placed around the top of
the wall and welded in place after the building was square to significantly
reduce the amount of possible tension. And in the case of an engineer
remember they purchase their "insurance" with your money by over-engineering
as a general matter of rule. I would venture to guess that if epoxying a
bolt was all that easy and far less requirement on proper preparation and
application then we would probably see more use of epoxied bolts in
structural tension applications. I still have yet to see anyone build a
typical stick built single story house by pouring a stem wall then coming
back later with drilled and epoxied anchor bolts.

As far as it being a chemical bond, yes it is but you are relying on a
chemical process in an uncontrolled environment plus the limited surface
area between the bolt/epoxy and the concrete. Where as a poured in place
anchor with any kind of perpendicular extension has more area of concrete in
which to hold on to.

There are other variables as well that impact the holding value of any
connection. The quality and grade of the bolt vs. the density and
consistency of the pour is probably the biggest factors in ensuring no
matter what method you anchor with the anchor will hold. If the concrete is
weak, it won't matter which method you choose. With the exception of a full
caged bolt that would require the entire chunk of concrete to fail.

As stated I have seen epoxied bolts pulled from concrete. With a backhoe
mind you but I have seen it. Since with a tower we are toying with several
thousand dollars worth of steel and aluminum and that's if it doesn't fall
on something or someone....

But again, I am not an engineer. And maybe all the engineers I've ever
drafted for were "old school". But nonetheless, I still remain a skeptic.

Michael Wood
KE7ENC

Michael ..So far, your conclusion does not mesh with what I have read at 
various sites, and in the past on this reflector.....  But then, the 
companies are selling their glue ....
but but but ... to engineer types, so... must be truthful?
Hmmm ... watching this thread, as I have a back porch that is going to be a 
base for a crank-up  ---  Mark, AA6DX