Cob: Use of Forms?

[Darel Henman]

Ray,

Thanks for the source information.  From reading the paper it states
that the only difference in the shuttered (formed) process and the
rammed earth (see Techniques 2 page, bottom section) is that rammed
earth uses mix with less moisture than the shuttered type and requires
more sturdy forms.  The rammed earth would be stronger then.  The
introduction section, paragraph one, states that "...Less commonly, but
still significantly, earth (or perhaps more often chalk) which was
rammed into place between shuttering can be found."  Indicates a rammed
earth, but on the the Techiques 1 page, the "shuttering process"
described seems to be a mix of cob earthen material of a considencty
between that required for a true monolithic bearing cob wall and the
light-clay mixture used for partitions or other non-bearing walls. 
Since it is wetter than rammed mixtures, it would shrink more when it
dries and cures, the shrinkage extent will depend upon the amount of
straw  mixed in.  This shrinkage might be able to be fixed by a
subsequent application to fill any cracks and top of the wall.  I will
read the rest of the report.

It would certainly be easy enough to make some small little test forms
to make some test pieces in.   Maybe a test size of 1 foot long by six
inches by six inches.  Maybe a  pound cake pan?   

Darel

Ray Luechtefeld wrote:
> 
> Hi Darel,
> 
> I don't think so, I believe the paper I'm looking at refers only to
> cob.  The page talking about forms (called "shuttering") is at
> 
> http://www.ihbc.org.uk/Cob_Paper/page2.html
> 
> What do you think?
> 
> Ray
>