SINDUENTERPRISES 58da055c0d4d89127c1d2b89 False 234 109
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EARTH RAMMER: The compressive strength of rammed earth is a maximum of 4.3 MPa (620 psi). This is less than that of concrete but more than sufficiently strong for domestic edifices.[4] Indeed, properly constructed rammed earth endures for thousands of years, as many ancient structures that are still standing around the world demonstrate.[5] Rammed earth reinforced with rebar, wood, or bamboo can prevent collapse caused by earthquakes or heavy storms, [citation needed] because unreinforced edifices of rammed earth resist earthquake damage extremely poorly. See 1960 Agadir earthquake for an example of the total destruction which may be inflicted on such structures by an earthquake. Adding cement to soil mixtures poor in clay can also increase the load-bearing capacity of rammed-earth edifices.[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.[6] Soil is a widely available, inexpensive, and sustainable resource.[7] Therefore, construction with rammed earth is very viable.[vague] Unskilled labour can do most of the necessary work.[4] While the cost of rammed earth is low, rammed-earth construction without mechanical tools is very time-consuming and laborious; however, with a mechanical tamper and prefabricated formwork it can require only two or three days to construct the walls of a 200 to 220 m2 (2, 200 to 2, 400 sq ft) house.[4] One significant benefit of rammed earth is its high thermal mass: like brick or concrete, it can absorb heat during daytime and nocturnally release it.[citation needed] This action moderates daily temperature variations and reduces the need for air conditioning and heating. In colder climates, rammed-earth walls can be insulated with Styrofoam or a similar insert. It must also be protected from heavy rain and insulated with vapour barriers.[5][8] Rammed earth can effectively regulate humidity if unclad walls containing clay are exposed to an internal space. Humidity is regulated between 40% and 60%, which is the ideal range for asthma sufferers[citation needed] and for the storage of susceptible objects such as books.[citation needed] The material mass and clay content of rammed earth allows an edifice to breathe more than concrete edifices, which avoids problems of condensation but prevents significant loss of heat.[4] Untouched, rammed-earth walls have the colour and texture of natural earth. Moisture-impermeable finishes, such as cement render, are avoided because they impair the ability of a wall to desorb moisture, [citation needed] which quality is necessary to preserve its strength.[citation needed] Well-cured walls accept nails and screws easily, and can be effectively patched with the same material used to build them.[citation needed] Blemishes can be repaired using the soil mixture as a plaster and sanded smooth. The thickness, typically 30 to 35 centimetres (12 to 14 in), and density of rammed-earth walls make them suitable for soundproofing.[citation needed] They are also inherently fireproof, resistant to termite damage, and non-toxic.[citation needed]
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