[Cob] could cob be masonry?

[Lance Collins]

Damon wrote,


>Straw doesn't rot away inside cob (now why, I don't know).

Years ago I found an explanation for this but unfortunately I didn't 
keep the reference.
It seems all materials have a natural level of moisture content and 
clay is one of the lowest
such that dry clay has too little moisture level to support rotting of straw.

What the conditions are to achieve a 'natural' moisture contents I 
can't remember.   Intuitively I would expect the moisture content to 
be the average of the relative humidity of the surrounding air but it 
seems this isn't so.

As someone with engineering training I find it frustrating to give 
such a vague explanation but I have never been able to find that 
reference again.

Lance
Victoria, AU

p.s. I saw a documentary recently on the building of the Alhambra(?) 
in Grenada, Spain.   The walls are cob (well, poured earth at least) 
and protected by a lime and clay render.