In a message dated 98-11-06 11:05:20 EST, stan@capeonramp.com writes:
> The hot dipped galvanized legs exposed to the soil, at the bottom
> of short base embedded in concrete, will erode very slowly.
Actually, the recommendation is for 4-5 inches of gravel at the bottom
to drain off the moisture.
> 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...
>
This is true but several TowerTalkians have experienced enough rust of
the legs at the top of the concrete base that the tower structure was in
peril. In other words, the rust was so bad that the tower was in danger of
collapsing. Applying a coat of roofing tar or other material to the steel in
the concrete up to a couple of inches above the top of the base will help to
prevent this.
BTW if you're having a building inspection of your base, it won't pass
unless the rebar is several inches from the dirt and not touching it.
Cheers, Steve K7LXC
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