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Which raw materials are used to make structural clay products such as brick and roofing tile?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
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.
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.

Structural clay products, such as brick and roofing tile, are manufactured using a combination of naturally occurring raw materials. These components typically include:

  • Clays or argillaceous (clayey) shales (35 to 55 percent): These act as the former, providing the necessary plasticity for shaping the product.1
  • Quartz (25 to 45 percent): This serves as a filler, which provides structural strength to the formed object.1
  • Feldspar (25 to 55 percent): This acts as a fluxing agent, which lowers the melting temperatures of the clay and quartz during the firing process in a kiln.1

These proportions are often found naturally within shale deposits, meaning extensive blending is frequently unnecessary. Manufacturers typically utilize local materials to minimize transportation costs. The final color of these products is determined by impurities present in the raw materials, most notably iron oxides, which react to the firing atmosphere. While these are the primary materials for traditional ceramics, it is important to note that some modern substitutes, such as concrete brick and tile, are instead made from mixtures of cement and aggregate.123