[TowerTalk] Tower Foundation Pouring

[JVarney]

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.