Cob: Cob Mixer or press? Also hot Oklahoma weather.

[Darel Henman]

Kenn,

Kenn Goodson wrote:
>  ............. snipped
> I was thinking of a cob press, rather than a cob mixer. Imagine taking
> clay/sand slip, not runny, but somewhat wet, layered with straw, and then
> pressed under pressure--I'm thinking hydraulic ram here, most on the list
> would probably prefer something human powered--rotated 90 degrees and pressed
> again. ................

What you are describing is a compressed earth brick (C.E.B.) with fibre
in it.  For what you have in mind I would ferment and age the straw in
the soil to break-down the straw into its fibre constituents and to
distribute the straw's lignin and pentosan to increase clayishness,
hardness and consistency.  Then let the mix dehydrate to the proper
percentage of water 5-10% thereabouts and make your compressed bricks. 
Data for compression strength for just C.E.B. is already available.

Just some ideas.

Darel

> It's the closest idea
> I have come up with that would imitate the pressure of human or animal feet.

Refer to the cinva ram for making C.E.B..


> If anyone has any comment on this, I would love to hear it. Please feel free
> to poke as many holes as possible into this idea.  Criticism will only make
> it better.
> 
> Secondly, how does cob with it's large thermal mass behave in hot/humid
> climates?
It works wonderfully.   In Japan they built all important warehouses
that stored old books, manuscripts and storehouses for food out of the
same materials as cob.  It regulated the humidity and temperature.  They
were also nice and quiet inside.

> I'm in central Oklahoma, and there are those dog days of late
> summer where the daytime temps get into the 105 degree range and nights never
> even get below the eighties.
Wood stick houses would do the same.   The massive walls don't conduct
or sink heat quickly.  When the walls reach 80 degrees in the morning
their liable to stay that way most of the day with little increases. 
The air cooler if you use those would only have to cool the air from the
ambient wall's 80 degrees down to 78 or so during the daytime.  Stick
walls can't do this all the 105 heat outiside is sliding into your
house.  Windows are your biggest heat gainers/losers.

Like those old canvas cloth water bags used to hold water for
automobiles radiators, the inside water cools as the outside of the bag
evaporates/sweats.  So will a cob  house be help to cool itself in humid
areas.  The absorbed water vapor will evaporate on the outside keeping
the temperature inside cooler.

> And this with ridiculous humidity levels.
> Anybody with experience with this type of climate?
> 
> Many thanks!
> Peace to you all,
> Kenn G

Regards,
 Darel