How were straw fibres used in some of the earliest clay bricks?

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traditional ceramics Stages in the slip casting of a thin-walled whiteware container. Clay powder is mixed in water together with a dispersing agent, which keeps the clay particles suspended evenly throughout the clay-water slurry, or slip. The slip is poured into a plaster mold, where water is drawn out by capillary action and a cast is formed by the deposition of clay particles on the inner surfaces of the mold. The remaining slip is drained, and the cast is allowed to dry partially before the drain hole is plugged and the mold separated. The unfinished ware is given a final drying in an oven before it is fired into a finished product.

In the earliest clay bricks, straw fibres served as a vital reinforcement material, marking them as some of the first known composite materials.1

When mud bricks were formed in wooden frames and left to dry in the sun, the clay would inevitably shrink, leading to the development of cracks. The addition of straw helped hold the brick together during this drying process, providing structural integrity and toughness despite the shrinkage. Once dried, these bricks were typically laid using wet mud mortar or bitumen to construct walls. This technique of using straw-reinforced mud bricks, often referred to as adobe, remains in use today in various regions across the Middle East, Africa, Asia, and Latin America.12