Cob: Earth Floor!

[SANCO Enterprises, LLC]

Recently I have had to do some non-standard repairs on floor surfaces and
here is what was done.

In support of what Vicki stated, tamping or ramming can be very effective.
Soil compaction is what you are trying to achieve and moisture content is
critical.  If you are going to compact the sub-base materials, you want very
little clay and optimum moisture.  You can determine roughly where this
point is by wetting soil material light and mixing it thoroughly a little at
a time.  The ideal point will be where it binds slight when squeezed in the
palm of the hand and the material still breaks apart.  This is about the
same as used for rammed earth homes.

For placement on floors, a 24" x 24" plate compactor is preferred with
material laid in at not more than 2 inches at a time.  I prefer to use
crusher fines that are available from most quarry operations where the
crushing of stone is taking place.  It's very economical and works extremely
well if it is >3/8" and has a good sieve particle distribution. Most of the
material when placed has been so hard, is has been difficult to cut-out
areas that were slightly high.

Because we have had to have a self-leveling floor, we made our own material.
Here is the mix design

fine sand (15% of dry cement component)
1 part gypsum (HydroCaL) or use a gypsum cement (DuraCal)
1 part slag cement (Blue Circle 120)
Portland Cement (10% by wt of dry components)
1 part coarse masonry sand to 1 part of combined dry cement components
Cement Plasticiser (1 to 2% of dry cement wt) use  Melment F-10 in fine
white powder or Lomar D
Thermoplastic Resin Powder (.05% by wt of dry cement component Airflex
RP-224) this is optional.  It gives the surface a very hard clean finish
Defoamer (.05% by wt of dry cement component  Foamaster PD#1 powder)  keeps
air bubbles from forming

Water content may be as high as 40%.  Add water until the material is in
flowable state that you want to use.  DO NOT make it too watery.

You must mix and place sufficient material at one time to get to a cut off
point .  This material will set in 15 to 25 minutes depending on temp.


SANCO Enterprises, LLC
Paul Salas, General Manager
P.O. Box 45741
Rio Rancho, NM  87174
(505)  238-1485
chansey at earthlink.net

----- Original Message -----
From: "Vicki Wicker" <vcwicker at asub.edu>
To: "Patricia Kerns" <pkerns at twistedroad.com>; "Darel Henman"
<henman at it.to-be.co.jp>
Cc: <coblist at deatech.com>
Sent: Friday, November 02, 2001 9:16 AM
Subject: Re: Cob: Earth Floor!


> I have to disagree. We troweled and we rammed. Ramming was much easier.
> Because you sprinkle the soil down dry (much lighter) and trowelling is
> massively hard work. Plus all of the mixing is totally  eliminated.
>