Have you been dying to know what rammed earth is? Well, today is your lucky day. Alternative builder / programmer Richard Schave is here to explain it to us…
Rammed earth is an ancient building technique which was used to build parts of the Great Wall of China. Some regions of France have a 300 year tradition of using rammed earth ? due to high limestone content of the soil which acts as a “cement”, providing superior adhesion and compaction. The building technique has seen a revival in recent years as people seek natural and low-impact building methods.
David Eaton, of Northern California’s Rammed Earth Works, has developed a modern method called Pis?, which employs engineered quantities of earth and cement shot into modular forms with a gunite hose.
The technique is only suited to drier areas, hence Australia and the Southwestern United States both have emerging rammed earth construction industries. Not surprisingly, rammed earth looks a little bit like adobe, which is similar in material and technique.
HOW TO MAKE A RAMMED EARTH WALL
1. Tamp layers of moist, sifted soil – mixed with a small amount of portland cement – into removable forms.
2. Continue until volume has been compacted by approximately 25 percent.
3. When the mixture has cured for an appropriate time, remove the form, place atop the first layer and repeat.
The best mixture for rammed earth contains approximately 30 percent clay and 70 percent sand, with a small amount of cement added. Finished walls are somewhat water resistant, and can be stuccoed, plastered, painted or left as-is. To protect the walls care must be taken to ensure that the roof-line overhangs sufficiently, as well as providing proper drainage.
Rammed earth walls’ high thermal mass helps to even out temperature fluctuations between day and night, making them easy to heat and cool.
Rammed earth construction is becoming economically competitive with standard construction methods. Other features like long-term energy savings, ease and speed of construction, make this construction alternative even more attractive. With the introduction of the engineered techniques of David Easton, the modern world is coming back to an ancient technology.
Posted by Richard Schave