An earth structure is a building or other structure made largely from soil. Since soil is a widely available material, it has been used in construction since prehistoric times. It may be combined with other materials, compressed and/or baked to add strength.
Soil is still an economical material for many applications, and may have low environmental impact both during and after construction.
Earth structure materials may be as simple as mud, or mud mixed with straw to make cob. Sturdy dwellings may be also built from sod or turf. Soil may be stabilized by the addition of lime or cement, and may be compacted into rammed earth. Construction is faster with pre-formed adobe or mudbricks, compressed earth blocks, earthbags or fired clay bricks.
Types of earth structure include earth shelters, where a dwelling is wholly or partly embedded in the ground or encased in soil. Native American earth lodges are examples. Wattle and daub houses use a "wattle" of poles interwoven with sticks to provide stability for mud walls. Sod houses were built on the northwest coast of Europe, and later by European settlers on the North American prairies. Adobe or mud-brick buildings are built around the world and include houses, apartment buildings, mosques and churches. Fujian Tulous are large fortified rammed earth buildings in southeastern China that shelter as many as 80 families. Other types of earth structure include mounds and pyramids used for religious purposes, levees, mechanically stabilized earth retaining walls, forts, trenches and embankment dams.
Earthbag building[edit | edit source]
The notion of building walls with sandbags or earthbags has been around at least 100 years.[1] Originally and into modern times these have tended to be burlap (hessian) fabric bags forming temporary structures acting as flood barriers or as military fortifications. It is unclear exactly when the first time this was done,[2] but there is some evidence that in military settings sandbag walls were being used prior to World War I. Indeed, some WWI trenches reinforced with oil impregnated sacks still survive, despite being intended to be temporary.[2]
Building permanent structures such as homes using earthbags is a more recent development.[1] Otto Frei experimented with earthbag building in the in 1960s in Germany.[3] In the 1970s, again in Germany, Gernot Minke and others at the Research Laboratory for Experimental Building at Kassel Polytechnic College were investigating ways of building earthquake resistant structures without cement. They used polyester and burlap tubes filled with pumice to make domed structures. With the Francisco Marroquin University in Guatemala and the Centro de Estudios Mesoamericano Sobre Tecnologia Apropiada (CEMAT) a structure was built in Guatemala in 1978 out of lime soaked cotton fabric bags filled with pumice sand.[4]
The Earthbag building method was popularized by Persian Architect Nader Khalili who eventually developed a building technique he termed Superadobe, where polypropylene bags or tubes filled with moistened adobe soil were used to form often domed structures. Khalili went on to publish 6 books and found the non profit organization Cal-Earth Institute (California Institute of Earth Architecture) in 1981.[5] He has been criticized for claiming his superadobe technique was "freely put at the service of humanity and the environment" at the same time as attempting to patent earthbag building techniques in very general terms in 1991. It is claimed he requested that all other promoters of earthbag building enter into a contract with him to continue their work.[1]
- ↑ 1.0 1.1 1.2 History of earthbag building on earthbagbuilding.com by Kelly Hart
- ↑ 2.0 2.1 Building with Earthbags. Joseph Kennedy. 1997 (available on earthbag building.com)
- ↑ Earthbag Building: The Tools, Tricks and Techniques. Kaki Hunter, Donald Kiffmeyer. New Society Publishers, 1 Jun 2004
- ↑ Building with Unbonded Pumice by Klaus Grasser / Gernot Minke published by Deutsches Zentrum, 1990 (reproduced on earthbagbuilding.com)
- ↑ Biography of Nader Khalili on calearth.org