Codes here allow un-reinforced concrete as "structural fill". So if the
hole is oversize, just fill it up without forms. Had to do that when a
base excavation found an abandoned septic tank. An extra 7 yds of concrete.
Grant KZ1W
On 10/13/2017 6:57 AM, Jim Thomson wrote:
Date: Fri, 13 Oct 2017 09:02:35 -0400
From: Steve Maki <lists@oakcom.org>
To: towertalk <towertalk@contesting.com>
Subject: Re: [TowerTalk] Concrete base - tower
< I'm trying to envision a situation where replacing dirt
<with concrete causes an issue....
<-Steve K8LX
## It doesnt. Concrete is heavier than dirt. And if dirt is used, it has
to be pounded down with the machine.
You put dirt in 4-6 inches at a time, called lifts. Then pound it down.
If you dont pound it down, then the dirt ends up with all sorts of air pockets.
I call that disturbed soil, which is exactly what you dont want.
## For folks pouring concrete, dont forget to use a vibrator on the concrete.
That eliminates the air pockets and voids. But it has to be done quickly, and
fast.
Dont over vibrate it, or rake it across too slow. Otherwise the aggregate,
typ
.375 rocks, that are in the mix of sand + concrete powder + water, will migrate
lower down, towards the bottom.
Jim VE7RF
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