Rammed earth is a process of compressing by tamping down with a pise a mixture of soil that is screened, comprising mostly sand and clay. I worked for an environmental organization that did a workshop on rammed earth construction back in 1979. I owned 40 acres in the NW corner of Montana back in the 80's that had perfect soil for rammed earth. I built a form and created a large test block of the rammed earth that withstood many years of weather until vandals knocked it down.

There are two rammed earth houses in my town. They look like smooth stucco finish from the outside. There are contractors that construct rammed earth buildings. Here is a blog with photos about rammed earth.

http://rammedearth.blogspot.com/