In a message dated 11/30/02 4:51:50 PM Pacific Standard Time, wz7i@arrl.net
writes:
> I am planning the installation of a self-supporting tower. My contractor
> asked me a question to which I don't know the answer. Is there any reason
> why he cannot pour the base in two pours as long as they are tied together
> by the rebar cage? The plans call for the foundation to be 9 x 9 at the
> base and then 5 x 5 at the surface. He would prefer to pour the 18" thick
> 9 x 9 foot section before the 5 x 5 foot section. Any reason why not?
It should be in one pour so that the base is totally bonded together. If
the bottom pour has 'gone off' and hardened, you wind up with two separate
layers.
Sometimes there are two pours if you have to have two trucks worth of
concrete but they are poured consecutively with little or no time delay.
Are you looking at something like a pedestal base where it's not a cubic
hole? Did you take the manufacturer's specs or have a PE design it? Sometimes
manufacturer's specs are pretty impractical (i.e. Trylon's undercut base, US
Tower's deep skinny holes) so it'd probably be easier if you could
reconfigure it for simplicity's sake. The problem is that the bases are
designed by engineers sitting in an office somewhere and they never have had
to install one of their (stupid) designs.
What kind of contractor wouldn't know the answer to your question?
Cheers,
Steve K7LXC
TOWER TECH
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