This ought to be an interesting thread!
My brother-in-law recently built his house with rammed earth in central California (in the City of Nipomo). To comply with the Uniform Building Code, and to satisfy the local building inspector, the house was constructed with concrete columns attached to a continuous grade beam below the walls and a continuous concrete bond beam on the top of the walls. The design analysis assumed absolutely no strength in the rammed earth walls themselves and depended completely upon the lateral strength of the concrete columns.
Because of the concrete columns, the construction sequence was actually made easier. Re-useable formwork was constructed for one wall panel. Half-sections of PVC pipe were fixed to the formwork to produce concrete keys that serve to "lock in " the wall panel. This formwork was re-used to construct all the wall panels. Once the wall panels were in place, the walls themselves served in part as the formwork for placing concrete for the columns and bond beam.
As far as building code design basis, the rammed earth wall panel would be catagorized as an "un-reinforced wall panel" which is not presently recognized for either lateral load carrying strength or for load bearing strength.
If anyone is interested in persuing code approval for such construction without the use of concrete columns, then it would be neccessary to put up a large sum of money to do run lab tests to gain ICBO approval. Yes, it is quite possible that rammed earth has potential as a "building material", but I would think that a little research and development would be necessary to iron out the details, such as, adhesive additives to increase strength, etc.
Concrete looks ugly, but I think my brother-in-law is satisfied with the result.
