David Gilbert wrote:
>
> Third question ... why would a solid copper wire that can exist forever
> within concrete without corroding, and exist virtually forever in normal
> soil without corroding, corrode when leaving the concrete to enter the soil?
>
The latter first..Different chemistry inside and outside the concrete?
But, copper is pretty resistant to corrosion in general.. I doubt it's a
concern.
But, for wild speculation's sake.. what if the soil chemistry and
concrete chemistry were such that you have a galvanic action causing a
current flow in the copper (or, perhaps, something like a DC potential
gradient.. maybe your tower is right next to that 3 GW HVDC line?)
Of course, we also assume that your concrete footing is in the middle of
a huge saltwater marsh, just to make the situation worse.
My only concern (and it's not a big one) would be my general aversion
(possibly not well founded in theory OR practice) to having metal
penetrate the concrete below grade, because of the possibility of
capillary cracks resulting from different coefficients of thermal
expansion. In reality though, I'd bet this isn't a real concern.
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