Rammed Earth vs. Adobe

Both are earth.
Both can be stabilized.
Adobes can be stabilized with asphalt emulsion or cement.
Rammed earth is stabilized with Portland cement.
Adobes are placed one at a time in a mortar bed. Mortar beds are the weak links in the adobe construction. Cracking and settling usually follow the mortar joints. In an earth quake the whole wall will shake at the mortar joints. The UBC requires adobes to have a compressive strength of
300 psi.

Rammed earth Is usually stabilized with Portland cement. With 7% cement the compressive strength of rammed earth is around 600 psi. It is more of a solid mass of earth. Rammed earth walls are made by putting lifts of dirt into forms and compacting or ramming it down and adding another lift or layer of soil and ramming it down. It is wider than adobe because someone has to get into the form to bond the next lift of fresh soil cement mix.

Earth & Sun Construction uses a mixing machine designed exclusively for rammed earth. With this machine we are capable of providing a consistent supply of soil with a percentage of cement. It is delivered to the forms by a conveyor belt where it is continually rammed from start to finish. No cold joints occur. This process makes the most monolithic structure possible. Wall sections are joined together with a ½ round keyway. The one cold joint in the wall system is vertical instead of the multiple cold joints that can occur by conventional rammed earth building or the multitude of joints in an adobe wall.