Thus, a well-planned adobe wall of the appropriate thickness is very effective at controlling inside temperature through the wide daily fluctuations typical of desert climates, a factor which has contributed to its longevity as a building material. After the sun sets and the temperature drops, the warm wall will continue to transfer heat to the interior for several hours due to the time-lag effect. The massive walls require a large and relatively long input of heat from the sun ( radiation) and from the surrounding air ( convection) before they warm through to the interior. In climates typified by hot days and cool nights, the high thermal mass of adobe mediates the high and low temperatures of the day, moderating the temperature of the living space. In addition to being an inexpensive material with a small resource cost, adobe can serve as a significant heat reservoir due to the thermal properties inherent in the massive walls typical in adobe construction. To withstand such loads, the codes typically call for a tensile modulus of rupture strength of at least 50 lbf/in 2 (0.345 newton/mm 2) for the finished block. Such an acceleration will cause lateral loads on the walls, resulting in shear and bending and inducing tensile stresses. The building codes require the building sustain a 1 g lateral acceleration earthquake load. Adobe construction should be designed so as to avoid lateral structural loads that would cause bending loads. In the United States, most building codes call for a minimum compressive strength of 300 lbf/in 2 (2.07 newton/mm 2) for the adobe block. they carry their own weight into the foundation rather than by another structure, hence the adobe must have sufficient compressive strength.

Maintenance of historic architecture in Agadez, Niger, by adding a new layer of mud rendering.Īdobe walls are load bearing, i.e. Typically the soils of the Southwest United States, where such construction has been widely used, are an adequate composition. Too much expansive clay results in uneven drying through the brick, resulting in cracking, while too much kaolinite will make a weak brick.

No more than half the clay content should be expansive clays, with the remainder non-expansive illite or kaolinite. Modern adobe is stabilized with either emulsified asphalt or Portland cement up to 10% by weight. Another source quotes 15–25% clay and the remainder sand and coarser particles up to cobbles 50 to 250 mm (2 to 10 in), with no deleterious effect. The most desirable soil texture for producing the mud of adobe is 15% clay, 10–30% silt, and 55–75% fine sand. Straw is useful in binding the brick together and allowing the brick to dry evenly, thereby preventing cracking due to uneven shrinkage rates through the brick. The soil composition typically contains sand, silt and clay. Etymology Īn adobe brick is a composite material made of earth mixed with water and an organic material such as straw or dung. Its wide use can be attributed to its simplicity of design and manufacture, and economics. Adobe bricks were used in Spain from the Late Bronze and Iron Ages (eighth century BCE onwards). Puebloan peoples built their adobe structures with handsful or basketsful of adobe, until the Spanish introduced them to making bricks. Cases where adobe structures were widely damaged during earthquakes include the 1976 Guatemala earthquake, the 2003 Bam earthquake, and the 2010 Chile earthquake.īuildings made of sun-dried earth are common throughout the world (Middle East, Western Asia, North Africa, West Africa, South America, southwestern North America, Spain, and Eastern Europe.) Adobe had been in use by indigenous peoples of the Americas in the Southwestern United States, Mesoamerica, and the Andes for several thousand years. Adobe buildings offer significant advantages due to their greater thermal mass, but they are known to be particularly susceptible to earthquake damage if they are not reinforced. In dry climates, adobe structures are extremely durable, and account for some of the oldest existing buildings in the world. The maximum sizes can reach up to 100 pounds (45 kg) above this weight it becomes difficult to move the pieces, and it is preferred to ram the mud in situ, resulting in a different typology known as rammed earth. In some areas a popular size measured 8 by 4 by 12 inches (20 cm × 10 cm × 30 cm) weighing about 25 pounds (11 kg) in other contexts the size is 10 by 4 by 14 inches (25 cm × 10 cm × 36 cm) weighing about 35 pounds (16 kg). There is no standard size, with substantial variations over the years and in different regions. They can be subsequently assembled, with the application of adobe mud to bond the individual bricks into a structure. Adobe bricks are rectangular prisms small enough that they can quickly air dry individually without cracking.

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