Mudbrick
A mudbrick, also called an unfired brick, is an air-dried brick composed of a mixture of mud with a binding material, such as rice husks or straw. Mudbricks are known to have been used since 9000 BCE.
From around 5000–4000 BCE, mudbricks evolved into fired bricks to increase strength and durability. Nevertheless, in some warm regions with very little timber available to fuel a kiln, mudbricks continued to be in use. Even today, mudbricks are the standard of vernacular architecture in some warmer regions- mainly in parts of Africa and western Asia. In the 20th century, the compressed earth block was developed using high pressure as a cheap and eco-friendly alternative to obtain non-fired bricks with more strength than the simpler air-dried mudbricks.
Ancient world
The history of mudbrick production and construction in the southern Levant may be dated as far back as the Pre-Pottery Neolithic A. These sun dried mudbricks, also known as adobe or just mudbrick, were made from a mixture of sand, clay, water, frequently tempered with chopped straw and chaff branches, and were the most common material for constructing earthen buildings throughout the ancient Near East for millennia. Unfired mudbrick is still made throughout the world, using both modern and traditional methods.The 9000 BCE dwellings of Jericho were constructed from mudbricks, affixed with mud, as were those at numerous sites across the Levant over the following millennia. Well-preserved mudbricks from a site at Tel Tsaf, in the Jordan Valley, have been dated to 5200 BCE, though there is no evidence that this site was the first to use the technology. Evidence suggests that the mudbrick composition at Tel Tsaf was stable for at least 500 years, throughout the middle Chalcolithic period.
The South Asian inhabitants of Mehrgarh constructed and lived in mudbrick houses between 7000–3300 BCE. Mudbricks were used at more than 15 reported sites attributed to the 3rd millennium BCE in the ancient Indus Valley civilization. In the Mature Harappan phase, fired bricks were used.
The Mesopotamians used sun-dried bricks in their city construction; typically these bricks were flat on the bottom and curved on the top, called plano-convex mudbricks. Some were formed in a square mould and rounded so that the middle was thicker than the ends. Some walls had a few courses of fired bricks from their bases up to the splash line to extend the life of the building.
File:SudanKhartoum-TutiIsland-BrickmakingCorinthia RomanDeckert20160207.jpg|thumb|Traditional brickyard on Tuti Island in Sudan, 2016
In Minoan Crete, at the Knossos site, there is archaeological evidence that sun-dried bricks were used in the Neolithic period.
Sun-dried mudbricks were the most common construction material employed in ancient Egypt during pharaonic times and were made in pretty much the same way for millennia. Mud from some locations required sand, chopped straw, or other binders such as animal dung to be mixed in with the mud to increase durability and plasticity. Workers gathered mud from the Nile river and poured it into a pit. Workers then tramped on the mud while straw was added to solidify the mold. The mudbricks were chemically suitable as fertilizer, leading to the destruction of many ancient Egyptian ruins, such as at Edfu; one well-preserved site is Amarna. Mudbrick use increased during the time of Roman influence.
In the Ancient Greek world, mudbrick was commonly used for the building of walls, fortifications and citadels, such as the walls of the Citadel of Troy. These mudbricks were often made with straw or dried vegetable matter.