[Cob] rebar, cob, rust, further corrosion

[Amanda Peck]

a) wasn't there a rumor around some years back that putting rebar in 
adobe--or some other form of earthen building--was annoying and to no 
purpose because twenty years later if you cut open the wall all you would 
find were rust tracks?

b) rust is BIGGER than straight metal, isn't it?  It swell, could it break 
something like concrete or cob?

c) couldn't find a link to it, but a major bridge in Nashville (Silliman 
Evans) was condemmed and rebuilt precisely because tiny cracks had let 
salt--to melt snow and ice--to seep into the reinforced concrete, rusting 
the reinforcing bar, which made matters worse, if I'm right on b).  My 
recollection is that a big chunk or two fell into the river before they 
caught it.

d) which would lead me to think that deliberately PUTTING rusty metal in 
almost anything is a bad idea.

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