[TowerTalk] Concrete tower fountains plans...some questions
n0tt1 at juno.com
Mon Jun 11 09:31:32 PDT 2012
I'm planning to erect a new 68' self-supporting BX tower and I'm
going over Rhon's specifications for the concrete foundation.
(I have NO desire to deviate from those specs.)
A few questions:
1. There's a grid of 3/8" rebar about 3" up from the bottom
and is about 4ft square and flat. What's the best
way to support that off the bottom of the hole while
the concrete is being poured around it? And will
the supports allow water to enter and corrode the rebar?
2. There's also a grid of 3/8" rebar about 3" below the
TOP surface of the foundation. The rebar is placed at 12" centers.
I'm *thinking* that the grid can be suspended from the wooden
jig I'll build to hold the anchor bolts firmly in place while the
concrete is being poured. From your experience, would
that be the best/easiest way?
3. I've read/heard somewhere that rebar in concrete
tower foundations should be connected/bonded to the tower
ground system. Seems logical, but is that true?
4. The Rohn spec sheet shows the TOP of the fountation
6" above grade. Why the 6"?...to allow for "growth" of the
soil around it? Why not, say 3" and dig the foundation
hole a little deeper?
5. The 1-inch anchor bolts have a nut and washer above
and below the U-brackets that support the tower. Is it
customary to place some anti-sieze compound on the
threads to easily allow minor adjustments due to any settling
of the foundation...say in 5-10 years or so?
73 and thanks for your input,
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