Hello Larry,
Critical issue is to allow water drainage from the legs of a short base
section.
If allowed to collect water the water may fgreeze expanding the leg,
splitting it and severly weakening the base section. as the leg section
is expanded with the ice, the galvanization flakes off exposing bare
steel for more rust/corrrosion. Keep in mind that the water is
mostly acid rain, a weak electrolyte, accelerating corrosion.
The hot dipped galvanized legs exposed to the soil, at the bottom
of short base embedded in concrete, will erode very slowly.
Exposing only a small surface area of bare steel to corrode.
corrosion propagation would be very slow as compared to
the useful life of the tower above ground...
Stan, WA1ECF Cape Cod, MA FN41sr
Larry Burke wrote:
> Barry asks
>
> <snip>
>
> "Can someone explain to me why the rebar WITHIN the concrete doesn't
> rust? Concrete always retains moisutre and absords it from surrounding
> soil, doesn't it?
> Rust is oxidation. Being underground, whether in concrete or soil,
> doesn't the minimal oxygen content under ground retard the rust
> formation?"
>
> <snip>
>
> I'd like to add...
>
> all the concern about the rebar being kept away from the dirt/water yet the
> Rohn drawings show the bottom of the tower legs should drop below the
> concrete, into the sand and gravel drainage bed, where they are presumably
> exposed to water most of the time. Won't this rust propagate up the tower
> legs? Granted they are galvanized and rebar isn't. I'd keep the rebar away
> from the dirt anyway, but often wondered about the tower legs
>
> Larry WI5A
>
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