rammed earth

rammed earth material consisting chiefly of soil of sufficiently stiff consistency that has been placed in forms and pounded down. It has been used for buildings and walls since ancient times and was employed in some of the most ancient fortifications in the Middle East. Pliny the Elder records the survival of a rammed-earth fort built by Hannibal 250 years earlier. The material has been recommended especially for subsistence homesteads and for farm buildings; it has been widely used in the Rhone valley. It is known in England by the French term pisé de terre. It is formed either into monolithic walls or into blocks, and in both forms it makes strong, durable walls with good insulating and fireproofing properties. Its resistance to water may be increased by stabilizing it with cement and by surfacing. Earth walls should rest on a foundation with a waterproof top and must be roofed immediately. The material usually costs nothing and does not require skilled labor. Adobe, unlike rammed earth, is sun-dried and is made without packing the earth down between forms. Cob and chalk mud are related building systems. The cob mixture consists of straw added to clay and water. It has been used in Japanese architecture and until recently was an important building material in some regions of Great Britain, particularly in Devonshire and South Wales. In the chalk-mud method, chalk is added to the earth and water. Sir Edwin Lutyens designed a monumental chalk building, Marsh Court in Hampshire, England.

Bibliography: See R. L. Patty and L. M. Minium, Rammed Earth Walls for Farm Buildings (1938); C. Williams-Ellis and J. and E. Eastwick-Field, Building in Cob, Pisé, and Stabilized Earth (1947).

rammed. Structure, e.g. wall, made by beating down earth contained between formwork or shuttering with a heavy implement. If cement and other strengthening ingredients are added, the rammed earth is pisé de terre. Compare adobe; cob; pisé.