I think it's more than just an ..."urban myth"... .
>From what I have seen, it's recommended
by the Tower Manufacturer.
73, Dick, W1KSZ
On Fri, Feb 3, 2017 at 1:11 PM, JVarney <jvarn359@gmail.com> wrote:
> There's an urban myth about "undisturbed soil." Hams believe
> that pouring concrete against undisturbed vertical dirt
> walls is the only way to place a footing. It is often the
> easiest way to do it and is perfectly acceptable, but when
> soils are soft it can be difficult to do.
>
> The other way to pour a footing, commonly used in
> commercial construction, is to over-excavate, build a
> full form, like this:
>
> https://goo.gl/MKNbLy
>
> After the concrete cures pull the form. Rent a "jumping
> jack" or "elephant's foot" compactor. Backfill the dirt
> around the footing in layers, then compact it
>
> https://youtu.be/lYndguhIEQc
>
> Done carefully and with a high level of compaction the
> footing will be as good as if the undisturbed soil
> method was used.
>
> 73 Jim K6OK
>
> Paul W9AC wrote:
>
> >> Despite efforts to brace the walls from blowing out as
> >> concreate was added, we still had slight bowing on the
> >> 140 ft. tower base (a 10 ft. x 10 ft. square). That
> >> resulted in a less than perfect square on two sides of
> >> the top surface.
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