In a message dated 99-08-27 08:47:55 EDT, smidtca@sprint.ca writes:
> I am about to pour about 5 cu yds of concrete into a roughly 5'x5'x5.5' deep
> hole dug by hand in gravel soil, thus making it impossible to have the
sides
> smooth vertically. The bottom is bellowed out rather roughly. I would
rather
> not have to put in forms for the concrete. In your learned opinions, would
> it be dangerous to just pour the concrete into the hole, over the rebar
> cage. Would a base poured thusly sustain a free-standing tower of 48' with
a
> TH5DX on top without going out of plumb with time. The frost goes down
about
> 3' to 4' depending upon the severity of the winters.
The tops of tower bases are typically above grade so the frostline
isn't much of any issue.
Using forms in the hole is used when the sides are sloughing but then
you have to do a very contientious job of backfilling the soil and
tamping/compacting it. You might want to have a concrete guy take a look at
it for a professional opinion. If in doubt, make the hole a little bigger and
use a little more concrete. The base's function is to exceed the overturning
forces so if the base is bigger, than it becomes less of an issue -
especially if you've got an irregular hole.
The Delhi is the same design as the Rohn BX series so I would use the BX
specs for guidance. If you don't have a Rohn book, you can get one at
http://www.championradio.com.
The book calls for a 5'-9" square pad 4 feet deep taking 4.9 yards of
concrete. Your proposed hole is about the same thing.
There are a couple of guys who have taken these towers down recently
and I'm sure they'd be interested in selling their concrete bases. Let me
know if you would like to contact them.
BTW, Delhi still makes the straight sections for the BX - straight 8's,
7's, etc. But I don't know how easy it would be to get them shipped from
Canada into the States.
Does anyone have contact information for the Delhi factory? I can't
seem to find them anywhere. Tnx.
Cheers, Steve K7LXC
Champion Radio Products
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