Cob: cob blocks?

[Darel Henman]

"SANCO Enterprises, LLC" wrote:
> 
> Experiences in different parts of the world, especially with earthen
> materials, leads one not to make rash judgments as to what something is or
> isn't.
What pray tell do you consider rash?   

> 
> Here are a few examples;
> 1) Prior to the arrival of the Spanish in the new world, Native Americans
> used a "puddled earth" method of construction. 
As was mentioned a wetter mix than cob material.

> Clay and straw mixed by hand and laid free form, one layer upon another. 
How did they lay the wet puddle mix you mention?  They must have had a
form and dried it dirst, or are you suggesting that it was a cob like
consistency mix and applied while damp?  I could not have been applied
dry like the sun dried adobe bricks with flatter surfaces and stay
structuraly strong due to shapes and adhesion. 
Again anything is possible, but apparently the formed sun dried adobe
clay straw slurrey made bricks worked best.


> It is not cob?
Not if you follow conventional definiations that adobe is a wetter
clay-straw slurry which is "poured" into a brick like form and sun dried
before application.

>  Or is our
> definition of cob one where the material has to originate in England..
Where the Dickens did you get this funny idea?

> or the Northwest to be called  cob?
The definitions by convention are to give us a distinction between the
two materials.  Adobe being defined as a sun dried brick of a clay straw
soil.  Applied after the brick has dried.   Adobe should also require a
mortar between the dried bricks.  

Whereas cob is a not so wet mixture of a clay soil and straw and which
is immediately applied to the structure being built.  Cob does not need
a mortar between successive layers either.

>  Is it the process or technique we are defining and not the material, or is it both?

Yes, a clear unified terminology needs to be developed.  That was what I
was mentioning about current terminolgy being confusing at times.

> 2) Darel also stated, > Cob material made into a block is fine, but it is
> not adobe.

Which is true based on conventional and accepted definitions.
>  Adobe is a  very wet clay slurry that is sun dried before
> application.   Adobe blocks would crack far more than a block of cob
> material. >
> 
> Darel, this is a matter of who is making the adobes---adobe production yards
> and those individuals using machinery do make a very wet adobe material,
> with and without straw.  Mom and Pop builders don't make them wet---just
> enough moisture to hand pat the material into the form--50 to 60 a day is
> good. 
For mom and pops it would be far easier to make and mix a watery
slurry.  Moreso than factories.

> Would not a truck load of cob material imported from the Northwest;
> delivered to the Southwest; mixed and formed into blocks; would they not be
> called adobe?
Not if you applied conventional definitions, that adobe bricks are made
from a watery slurry, dried and then applied, whereas a cob mixture is
mixed with less water and possibly more straw and appled right away. 

Better terminology may be created some day, but for the time being the
conventional definitons exist.


> 3) Our good friends, Bill and Athen Steen, made straw-clay blocks in
> Obregon, MX that only contained enough clay to bind the material together
> and definitely could not be poured.   It had to be packed by hand into the
> form.  Is this cob with just extra straw or a poorly made adobe?

By conventional definition it would not be adobe, it could be a "dry
light clay" if you wished to simply  "light clay" (a lot of straw with a
clay soil covering), which is sounds closer to what you describe. 
One could say a "cob with double straw content" or whatever conveys the
proper meaning.

>  Or maybe it is something else?  
I told you what I would call it.  What would you call it without taking
31 words or more?

> 
> 4) If forms are used and cob-like materials are used (clay-sand or
> soil-straw) with a zero slump or less, and a concrete vibrator is used to
> consolidate the material, what do we call the finished product? 
If you used a concrete vibrator then you have a lot of water in the
mix.  So you are talking about an adobe being pouring into a large
form.  

................
> Every time someone tries to define an earthen construction process or
> technique, a variant with the same material properties pops-up and
> re-definitions start up again, or clarifications must be stated, or
> exceptions noted.  
That underscores my statement that a useful terminology needs to be
devised.  In the meanwhile we will use conventional definitions and
explanations thereto in order to convey the material or method as you
must agree.


Cheers,
  Darel