Rammed earth is an ancient building technique in which moist earth is compacted into a rough approximation of sedimentary rock. Using forms, rammed earth may be shaped into bricks or entire walls. Dating back as far as 7000 b.c.e., it was used in portions of the 2,000-year-old Great Wall of China as well as temples in Mali and in Morocco. Romans and Phoenicians introduced the technique to Europeans, and it became a popular building technique in France, where it became known as pisé de terre. In the United States, it was used for both gracious Victorian homes and low-cost housing.
Today, builders add cement to the earthen mix, which results in stronger, waterproof walls. In traditional rammed-earth construction, hand or compressor-powered tampers are used to compact a mixture of moistened earth and cement between double-sided wooden forms to about 60 percent of its original volume. In a newer technique, a high-pressure hose sprays the mixture against a single-sided form. Sometimes steel-reinforced bars are also used.
Previous question:
Why is the term penny used in nail sizes?
Next question:
What is a yurt?
