Cob houses are very unique and earthy.
adobe, cob, & soil cement
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Soil has been used to form structures for human habitation since the beginning of time. These have mostly carried the names of both adobe and cob, depending on where the construction was at. As a 50+ year resident of the American southwest, I've always referred to earthen homes as adobes. This Wikipedia webpage talks about adobe....
http://en.wikipedia.org/wiki/Adobe
Much is heard today in the world of alternative building about cob, particularly in the USA's Pacific northwest and the British Columbia province of Canada. Here's some info on the version of mudwork called cob....
http://en.wikipedia.org/wiki/Cob_(material)
Although many examples of ancient buildings made of mud exist in North America, a great number of houses have been lost to the weather....destroyed due to the owners failing to protect and maintain the structures from the negative effects of rain and wind. Virtually all of these were made before the existence of cement in the world.
Cement stabilized soil for building is known in the world for making adobe mud more water resistant. The commercial adobe makers in the American southwest are said to be all using cement now to give their bricks more strength and durability.
Asphalt emulsion is what's specified by the State of New Mexico in it's building code for a stabilizer in adobe constructions. It's mixed into the brick-making mud and exterior plaster also.
Many soils are compatible with cement directly without adding sand. I've seen others, however, that came out far better when sand is added to the mix,...and some that didn't make much sense to go soil cement at all, as in gummy, high clay soils.
Soil cement plasters help reduce dependency on costly hauled in
aggregates and large volumes of cement used in many mixes for traditional construction. It's best to try different soils in your area to find what actually is the best combination for strength, economy and durability. Remember that sufficient sand in the mix is critical for quality brick ....about 70% by volume.
There may be a way to effectively use on site soil to your advantage and avoid trucking in dirt from miles away. Our site soil here is not high enough in clay content so we mix it with another dirt brought from not too far away.
Using soil cement in floors comes with considerable risk of deterioration. The fears of the scraping effects of moving furniture around on a floor, for example, keep me making my walked on surfaces out of concrete or similar high strength
substances (tile, stone, brick).
The American southwest and New Mexico in particular has had a long tradition of the use of adobe floors. Some used animal blood or manure to strengthen the mud and give the floor a longer life.
Near Mancos Colorado, I saw a floor I'll never forget that was made with blood. The soil there was a type of black shale. The builder just loosened the topsoil, mixed in blood from a slaughterhouse. The clay soil while drying, pulled open, leaving a web of wide cracks.
When completely dry, they filled the cracks with a contrasting light colored mortar and the floor came out looking like an amazing perfectly laid floor of natural random stones, tightly fit together...and it did it by itself !
