Mud brick is a building material that uses readily available resources such as mud, sand, clay and water. It is most often made in hot climates that do not have an ample supply of stone or wood. Some of the oldest structures known to mankind were made with mud bricks. Such structures are often found in Africa, Asia, the Near East and parts of Central and South America.
There are two basic methods for making mud bricks. Traditional or puddle mud bricks are made from mixing together mud, sand, clay and water, along with a binding material such as straw. This mixture is then poured into a mold and left to dry for about 25 days. Pressed mud bricks are made using less water and are forced together through an applied pressure that forces the mixture into a frame or mold. Pressed mud brick will often require a binding agent such as concrete to make it more durable.
The lifespan of a sun-dried mud brick is about 30 years. This is because the materials are less well bound together. Kiln-dried or fired bricks take on more of the quality of pottery and ceramics, meaning that they are hardier and will last longer. Well-made pottery will survive for thousands of years, even when broken into pieces.
Adobe is similar to the mud brick and is used to make environmentally friendly houses. It is more durable and offers insulation in winter and cooling in summer. Like mud bricks, adobe is made from sand, clay, mud and straw before being left to dry in the sun. Adobe is widely used in Africa and Mesoamerica.
Evidence of mud brick buildings turn up in the archaeological record. These buildings, however, do not retain their original form. Brick and stone will weather, and weaker stones will crumble, but mud brick usually will crumble in a shorter amount of time. This means that new mud brick buildings are often built atop the crumbled and broken remains of the previous structure. In the near east, this has led to the development of hills or tells where the settlement has gradually risen up as new layers were built upon old layers.
One example of an archaeological find involving mud brick is Catal Hoyuk in Turkey. About 1,000 buildings have been discovered on the site, suggesting an estimated population of 6,000. All of the buildings were made using mud bricks. Another example is the tell of Jericho, where archaeological evidence from the layers of debris suggests that the Biblical story of the fall of Jericho might have some historical truth.
In 2011, it was estimated that half of the world’s population lived in mud brick or adobe houses. Many modern cities are predominantly made using mud bricks, including the Malian capital of Timbuktu and the Chinese city of Kashgar. In Timbuktu, structures made using ancient and modern architecture often sit side by side, with only their building material in common.