What is Rammed Earth?
To answer that question you must go back many centuries - to 3000BC China. Traditionally rammed earth consisted of local sub-soils combined with a small amount of water. The mixture was then placed into form work and compacted by hand. Rammed earth prospered where the sub-soil had an appropriate composition of clays, sands, and gravel. The climate of the area played a large roll as well, high diurnal temperature swings (daytime high vs. nighttime low) yielded a strong wall with a high thermal mass that kept the buildings warm in winter and cool in the summer.
Since rammed earth's revival in the 1970's many changes and adaptations have taken place. Modern soil mechanics have been used to identify appropriate soil compositions. Concrete forming technologies have increased the speed and complexity of rammed earth forming and pneumatic compaction tools have increased soil placement rates. Adding portland cement to the mix has made it possible to construct rammed earth with a variety of soil compositions and meet today's strict structural engineering requirements. With new admixture chemistry we have the ability to modify the hydrothermal properties of the material. Finally, the inclusion of rigid insulation panels have made it possible to use rammed earth in most climates. We can now specify rammed earth construction in almost any situation and receive the benefits of this beautiful construction technique.