[Cob] Arches

[Ernie Wisner]

here is the link i was speaking of: http://www.calearth.org/Emerg_files/VillageEntryRug.jpg
 
so you all let me know what you think.
Thank you for the time
Ernie
 
On Thursday, October 21, 2004, Ernie, you wrote:
> I looked into the super adobe domes and noticed something; the arches
> are formed by a single tube of adobe the wall is built behind the
> form. Well I got to thinking and wondering if you could do the same
> sort of thing with cob instead of corbelling the arch.

Yes, but as you build up the layers of cob behind the arch-tube, it is 
still
"corbelling"... : )

> Well being new to all this I would like your opinions on the
> following Idea. Ok sew a tube out of burlap (to the proper size
> needed for the arch) build your Cob wall to the bottom of the arch.
> Fill burlap tube with Cob and drape over Form wait till it dries to
> leather hard and drive nails into the wall side and set the arch in
> place. Then build the wall around the cob and burlap form.
> Tada... no corbelling and you have an arch.
>
> Well my first: question is how strong would it be?

At least as strong as corbelling alone...probably more so, if the straw 
in
the cob in the tube follows the curve...  The reason for corbelling an 
arch
is to extend the sides out, without having to depend on building a form 
to
provide interim support until it sets...

> Second: would the cob take up the load above the arch form or in the
> arch form?

Yes, loads will be transfered down in both ways

> Third: would it work in your opinions?

Yes, as long as you don't push it beyond the compression/tension 
potential
of the material, but I'd recommend you also post this to the cob list 
and
report back to us on their answers... : )

> Yes I know I have to test it to get all the answers via direct
> observation; however I can develop a hypothesis now. Thanks all, 
Ernie.

It just shows you're thinkin'..... : )    - Don





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