Cob: Re: Cob Machine

[SANCO Enterprises <Paul & Mary Salas>]

Otherfish at aol.com wrote:

> Paul, good to hear of your success with the pump - when you say " butter & a
> 16" height"  does that mean that you could use you pump to move cob from a
> mixer to a wall in a plastic state that would be buildable with?

Yes, this is the primary reason that the apparatus was built. During the demo
yesterday, I hooked up a 2" concrete hose to the pump and had one person stacking
and layering the mud. We got almost 20" high at a 2" slump.  Still too wet to
suit me.  Using this method, I want to be able to build 6'-0"  high fully
stabilized garden walls in a day.

> Could you use the pumped output to form a series of courses wall on a perhaps
> 12" to 18" wide wall with a course depth of 16"?  That would be really
> significant for building with cob.

This is exactly how we intend to use the machine.  One of the persons attending
the demo yesterday was a landscaper who builds water falls and he commented that
the machine would be ideal for his purposes.  Build/sculpt the shape with
cob/adobe and then veneer the waterfall with concrete from the same machine. We
with be experimenting in the lab next week with different admixtures such as fly
ash, kaolin clay, sodium silicate, aluminum hydrate, talc and yes, even lime.
Since most of the local production adobe producers use emulsified asphalt to
stabilizer their adobes, we will also be testing this as a component with other
admixes. We want to be able to find the most economical additive or combinations
of several that will get the cob to gel and set quickly and still be able to
shape and square the material with a working life of 10 to 30 minutes.  A 1200 sq
ft house in 2 days is an ambitious goal  ! ! !


> Also , how do you mix your material?

Because I used a "Little Giant"  plaster mixer tub to hold the material, I also
hooked up a hydraulic motor to the paddles to agitate the mud and get it to move
toward the feed screw to the pump.  For the demo, I simply used the paddles to
mix the material.  We were able to fill the 1/3 yd hopper completely full without
stalling or otherwise affecting the performance of the machine.  During the next
month, I will be designing and building my own pug mill that will be only 18" off
the ground and discharging to a conveyor that will feed the hopper on the pump.

> Do you have straw in your mix. , If not, would your mixer work to include straw
> & result with an essentially "firm yet plastic" consistency to the output ( as
> in theconsistency that cob is normally made?

The addition of straw would not be a problem.  Since the demo was done in the
field with top surface material, there were stones, roots and sticks in the mix.
some of the roots were heavy and long as I had to remove a great number from the
paddles after the machine was cleaned out.  The larger stones caused some
cavitation in the pump discharge and for future tests, the material will be
screened.  I need to establish production rates and I need to have a known
constant in the material.

> Would like to know more about your research into mixers & etc. as this is a
> real issue for effective production of cob to will be competitive with
> standard methods of construction - got to find a way to get the labor content
> reduced WAY LOWER than what it is with currently available techniques.

If you work with mud, you soon realize two things--it takes a lot of material to
build anything and it's a lot of work with multiple steps.  Doing this manually
with any production rate is only a dream and if you're paying for the labor, it's
very expensive.  I believe that using mechanization to eliminate as much of the
labor is the key to cost efficiency and using what nature gave us (earth) and a
little modern chemistry we can be competitive with other forms of construction
methods.  Imagine a wall system that is structurally sound, waterproof and has
the exterior surface finished in one step without the use of cement or other
manufactured products added to your process? It can and will be done.........very
soon.

Paul Salas
SANCO Enterprises, LLC
Albuq., NM