[Cob] Good clay?

[Bill&Julie]

Hello Dave,,  ~¿~

The thin-ness of your slurry is due to the ratio of the sample to water...
And that is immmmmaterial, if you weighed all of the stages of the
process. That is, after the samples have been dried out in an oven.
What you are looking for in the analysis is ratios of each sub-divisions
of your sample. So it does not matter how much you start out with,
but the percentages of each part to the whole.
Now there is a chart for your findings on the net...
http://plantphys.info/Plants_Human/soillab.html

But the only reason that a person would need to get this carried away
is for documenting and quality control. And this may be important to
people in government. Also this may be important for your peace of
mind for repeatability of your process.
My attention to this kind of detail comes from 13 years as a QC-QA
inspector in a machine shop..
Once you can keep your "process in control" then you can start
the construction in earnest... But first I would make test bricks,
and small test walls, and small test arches. And figure out some
repeatable way to load each until they break, and record the results.
Once you find the best mix, Build with a great deal of confidence.

Hope this helps,, bill  ô¿ô



----- Original Message ----- 
From: "Dave Brown" <quahog at netnet.net>
To: "Bill&Julie" <wkbjkb3 at mn.rr.com>
Sent: Friday, May 05, 2006 9:33 AM
Subject: Re: [Cob] Good clay?


> Hello Bill and all.
>
> I know the shake test isn't all bunkum, which is why I said:  "I know
> that there are some doubts cast about the shake test, but Ithink it's
> at least given me an idea of what I have to work with."  It is not a
> precision analysis.  But as I said it gives me an idea of what I have
> to work with.  Today, after two days of sitting undisturbed, there is
> hardly any sediment in the bottom, less than 10% of the total liquid
> volume.  The clay is still mostly in suspension in spite of being a
> pretty thin slurry (thinner than maple syrup).  So, I think I have a
> good supply of very good clay right here in my back yard.  Unless,
> that is, my slurry should be thinner?
>
> My next question is whether there are any other tests that I could
> make before going ahead and making my first ever cob loaf or brick
> (aka adobe).  I'm thinking I should make one each using 1-just clay,
> 2-clay and sand (ratio???), 3-clay, sand, and straw, clay, sand and
> paper (padobe?).
>
> any other tests I should make, or should I just go ahead and start
> building?  I know that cob/adobe isn't an exact science and I'm
> hoping that list members will help keep me from over analyzing the mud.
>
> Dave Brown
> Green Bay, WI