Science Fair Project Encyclopedia
- This page deals with adobe, the construction material. For information about the software company, see Adobe Systems.
Adobe is a building material composed of sandy clay and (usually) straw, which can be cast into bricks or shaped directly into walls using wooden frames. Adobe structures are easily damaged by excessive moisture , but offer significant advantages in hot, dry climates, as they remain cooler than alternatives based on more "modern" materials. It has many similarities to the Cob traditionally used to construct cottages in parts of England, but cob is never cast into brick form, and is also somewhat differently constituted so that it will survive in a wet climate.
Adobe is from the Spanish adobar which means "TO PLASTER" and is traceable through Arabic tauf to an Egyptian hieroglyph meaning "brick". The word may be pronounced ah-doh-bee or uh-doh-bee. It can refer to either the bricks, the material itself, or an entire building made of adobe. Buildings made of sun-dried earth are common in the Middle East, North Africa, and in Spain (usually in the Mudejar style), but adobe had been in use by Native Americans in the Southwestern United States and the Andean region of South America for several thousand years, although often substantial amounts of rock are used in the walls of Pueblo buildings. This method of brickmaking was imported in the 16th century by Spaniards from Mexico and Peru.
A distinction is sometimes made between the smaller adobes, which are about the size of ordinary baked bricks, and the larger adobines, some of which are as much as from one to two yards long.
Adobe, sometime abbreviated 'dobe, soil or land is land, such as sometimes encountered in the San Luis Valley of Colorado which is a hard packed clay. During or immediately after a rain, a road in such land is quite slick, although not muddy as the rain does not penetrate the clay very quickly
Composition of adobe
Adobe is a mixture of clay and sand. Too much sand and the material crumbles; too much clay and it will crack. Straw is sometimes, even traditionally, added to the mix when making adobe, but offers no particular advantage. To find the right combination experiment with the materials at hand until your bricks come out right. The same combining of sand and clay is used by Pueblo Indians to make the raw material for production of pottery or even to make molds for the casting of jewelry.
Bricks are made in an open frame, 25 cm (10 inches) by 36 cm (14 inches) is a reasonable size, but any convenient size is fine for your own use. After the mud is put into the frame the frame is removed. After a few hours the bricks are put on edge to finish drying. Bricks should be dried in the shade to avoid cracking.
Use the same mixture you use to make bricks for mortar when laying the bricks and for plaster on the interior and exterior walls. Some ancient cultures used concrete for the plaster to avoid rain damage. It is sometimes useful to include occasional pieces of wood as you lay a wall to give something to nail insulation onto, and stone can be used for additional strength.
Bricks can be made waterproof by adding emulsified asphalt to the mud. To test bricks for waterproofing immerse them in water for 24 hours. A good brick will not soak up more than about 1.6 mm (1/16th of an inch) of water. To test for strength, drop a finished brick from a height of 0.9 m to 1.5 m (3 to 5 feet) to see if it breaks. Sometimes if the sand is too fine, the finished bricks will be weak.
The biggest structure ever made from adobe (bricks), was the Bam Citadel, which suffered serious damage, up to 80%, by an earthquake on December 26, 2003. Other large adobe structures are the Huaca del Sol in Peru, built using 100 million signed bricks, and the ciudellas of Chan Chan, also in Peru.
Because an adobe wall, either made of bricks or using a rammed earth technique, is quite massive it will hold heat or cold. That means insulation needs to be put on the outside of your wall so once the wall is warmed up it will maintain the proper building temperature. A south facing adobe wall may be left uninsulated in order to collect heat during the day. It should be thick enough that it remains cool on the inside during the heat of the day but should be thin enough that the heat can be transferred through the wall by evening. Such a wall can be covered with glass to increase heat collection. Used in a passive solar home, such a wall is called a Trombe wall. note: not good insulation!, large thernal mass, therefor this type of construction is only good in very southern climates. In northern climates it is almost imposible to heat a home of this type as the heat is leached by the ground and the walls.
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details