Rammed earth
[2] Edifices formed of rammed earth are found on every continent except Antarctica, in a range of environments including temperate, wet,[3] semiarid desert, montane, and tropical regions.
Making rammed earth involves compacting a damp mixture of subsoil that has suitable proportions of sand, gravel, clay, silt, and stabilizer if any, into a formwork (an externally supported frame or mold).
Tamping was historically manual with a long ramming pole by hand, but modern construction systems can employ pneumatically-powered tampers.
This is necessary if a surface texture is to be applied, e.g., by wire brushing, carving, or mold impression because the walls become too hard to work after approximately one hour.
In modern rammed earth buildings, the walls are constructed on top of conventional footings or a reinforced concrete slab base.
The form must be durable and well-braced, and the two opposing faces must be clamped together to prevent bulging or deformation caused by the large compressing forces.
The compressive strength of rammed earth is dictated by factors such as soil type, particle size distribution, amount of compaction, moisture content of the mix and type/amount of stabiliser used.
[citation needed] The United States Department of Agriculture observed in 1925 that rammed-earth structures endure indefinitely and can be constructed for less than two-thirds of the cost of standard frame houses.
The technique was used to construct the Borough House Plantation[12] and the Church of the Holy Cross[13] in Stateburg, South Carolina, both being National Historic Landmarks.
Constructed in 1821, the Borough House Plantation complex contains the oldest and largest collection of 'high style' pise de terre (rammed earth) buildings in the United States.
Six of the 27 dependencies and portions of the main house were constructed using this ancient technique which was introduced to this country in 1806 through the book Rural Economy, by S. W. JohnsonAn outstanding example of a rammed-earth edifice in Canada is St. Thomas Anglican Church in Shanty Bay, Ontario, erected between 1838 and 1841.
[citation needed][14] In 1936, on a homestead near Gardendale, Alabama, the United States Department of Agriculture constructed experimental rammed-earth edifices with architect Thomas Hibben.
[citation needed] The houses were inexpensively constructed and were sold to the public along with sufficient land for gardens and small plots for livestock.
[citation needed] A notable example of 21st-century use of rammed earth is the façade of the Nk'Mip Desert Cultural Centre in southern British Columbia, Canada.
[17]: 55 The "Daqing Spirit" represented deep personal commitment in pursuing national goals, self-sufficient and frugal living, and urban-rural integrated land use.
[17]: 55 In the context of the Sino-Soviet split, Mao urged that planners should avoid the use of Soviet-style prefabricated materials and instead embrace the proletarian spirit of on-site construction using rammed earth.
[17]: 55 The Communist Party promoted the use of rammed earth construction as a low-cost method which was indigenous to China and required little technical skill.
During the Third Front campaign to develop strategic industries in China's rugged interior to prepare for potential invasion by the United States or Soviet Union, Planning Commission Director Li Fuchun instructed project leaders to make do with what was available, including building rammed earth housing so that more resources could be directed to production.
