[TowerTalk] Anchor bolt material

[Mickey Baker]

You're asking for engineering analysis of a non-standard scenario. Any
advice would be risky.

1.125" bolts in a 2.5" diameter hole leaves a lot of space for fill. It
appears to me that you'd want to use a structural epoxy like Strong Tie,
but their data sheets don't cover this situation. I am using 1.125"
threaded rod in a 1.25" hole with Strong Tie... It will consume less than
two 22 ounce tubes. Your situation would use about 6 of those, but may not
be strong enough, I don't know. Cost is $30+ per tube! and you need the
mixing nozzle and a two part dispenser if you're doing it yourself.

Concrete mixes probably don't provide enough adhesive strength to prevent
pull out at load. Again, that's an estimate, not a certainty. I wouldn't do
it for my tower.

Do what you will, you're into a custom engineering situation. In my
estimation, you need smaller holes or lots of structural epoxy.

I'd hire an engineer with experience in customized use of structural
adhesives. Or maybe someone here has that experience and can shoot from the
hip.

I'd get a professional opinion and put the project off a week. Better safe
than not.

73,

Mickey N4MB

On Sunday, October 12, 2014, Marvin Shelton <marvs at att.net> wrote:

> Here’s a question for everyone. I’m installing a new T-base for my
> crank-up US Tower so that I can use the raising fixture and stop climbing
> it when it’s retracted. (getting too old for that) and I’ve got the holes
> prepared and am wondering about the anchoring material to use.
> I’ve drilled the holes 2.5” in diameter to account for the nuts at the
> base of the anchor bolts, which I’ve had to cut off because I couldn’t go
> deep enough. So now I have 2.5” diameter holes to install 1-1/8” anchor
> bolts in.
>
> My obvious choices are anchoring epoxy, which is expensive at over $20 per
> tube, Quikrete anchoring cement, and I just discovered something called
> Rockite- for anchoring and patching.  I’m hoping that any of these choices
> will work. I’d like to save a few $$ and use the Quikrete which will be
> much easier to use (mix like concrete and pour into the holes). It has a
> pull-out strength of 14,100 psi  after 24 hours and 21,000 psi after 28
> days.
>
> Anyone have experience with any of these products. I’d like to do my pour
> today if possible.
>
> Thanks in advance.
>
>
> Marv
> wa2bfw at arrl.net <javascript:;>
>
>
>
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-- 
Mickey Baker, N4MB
Fort Lauderdale, FL
*“Tell me, and I will listen. Show me, and I will understand. Involve me,
and I will learn.” *Teton Lakota, American Indian Saying.