Re-using Cob?

[Shannon C. Dealy]

On Wed, 30 Jul 1997, Speireag wrote:

> Hallo all.
> 
>     We will be building our house in sections, and part of the construction
> may involve taking down interior (non-load-bearing) cob walls as we adjust
> the use of our interior space.
> 
>     Is cob re-usable?  If we knock it to pieces, put it in the mixing spot,
> jump up and down on it, wet it down, and mix it, will we have cob?  Will
> the straw survive two wettings?  Or does the ex-cob wall become backfill
> someplace where we don't want drainage?
> 
> -Speireag.

I've never head of anyone trying this with fully dried cob, my greatest
concern would be that if you simply "break" it up, I would expect that you
are going to break alot of the straw fibers which would make the new cob
weaker due to shorter fibers.  My guess is that it would be alright if you
broke it into some large chunks (as big as one or two people could carry),
and then let the chunks soak in water in a covered pit (this might take
days or weeks since you don't want to add to much water, but it would
need to soak completely through all of the chunks).  At some point if
it has soaked up enough water, you should be able to start breaking it up
and working it without breaking all of the straw fibers.  I don't think
there is much danger of damage to the straw from wetting it for reuse,
since it is heavily coated with clay and sand which should help to protect
it from decay.

Of course I'm only guessing ...  Care to volunteer to collect the
experimental evidence and report back :-)

Shannon Dealy
dealy at deatech.com