clay construction techniques
An Adobe brick is an air-dried cube made of clay, sand and gravel, which is formed by hands or pressed into a mold with a vibration press. Sand is added to fatty clay and sometimes fiber-containing substances such as straw or animal excrement from herbivores such as camel, cattle and horse is added. Vegetable fibers reduce weight, improve thermal insulation and provide tensile strength, reducing cracking during drying. In heavy rain, the clay stones become soft again, clay walls must be protected against permanent wetness and rain. When burned, clay forms a regular brick, or clinker.
In English-speaking countries, unfired brick construction methods are often referred to by the Spanish term Adobe, which is derived from the Arabic word “tôbe” = brick. The term was spread through Spanish descriptions of pre-Columbian buildings in Central and South America. The Sun Pyramid in Teotihuacán, the Huaca del Sol and the Huaca Larga in Peru are the largest Adobe buildings in the world.
Clay is used to make the adobe stones, which are usually mixed with sand, vegetable fibers or other fillers. Too much sand reduces the bearing capacity of the stones, too much clay causes them to crack. The addition of dry or soaked straw (as is common in Egypt) is also common practise. The carefully kneaded, viscous clay mixture is traditionally pressed into rectangular wooden molds, nowadays often also in metal molds. Once the mass has hardened, the frame is removed from the mold. Before drying, bricks with a high clay content are usually stored in the shade, as too rapid evaporation of the water can cause cracks. In parts of Latin America and Mesopotamia, the bricks are also exposed to direct sunlight to dry.
Adobe bricks are sensitive to running water and strong moisture (however not to increased humidity). Thanks to good heat retention, they offer advantages over many other building materials in arid, warm regions such as Egypt, Iran, Yemen or Bolivia, despite the mediocre thermal insulation. The bricks become warm during the day and slowly release the stored heat to the environment at night.
This means that a building made of clay bricks stays cool during the day and warm at night.
In areas with strong solar radiation, buildings on the sunny side are provided with a thicker wall in order to be able to store as much energy as possible. To increase the heat storage of the wall, glass or translucent wall insulation material is placed at northern latitudes to keep the heat in the area (the short-wave light radiation is transmitted, but the long-wave heat radiation to the outside is slowed down).
Also read about other clay construction techniques.
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