[TowerTalk] Concrete base - tower

[Grant Saviers]

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 at oakcom.org>
> To: towertalk <towertalk at 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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