Clay Bricks
Modern clay bricks are formed in one of three processes soft mud, dry press, or extruded.
Mud bricks
The soft mud method is the most common, as it is the most economical. It starts with the raw
clay, preferably in a mix with 30% sand to reduce shrinkage. The clay is first ground and
mixed with water to the desired consistency. The clay is then pressed into steel moulds with a
hydraulic press. The shaped clay is then burned at 1000 °C to achieve strength.
In modern brickworks, this is usually done in a continuously fired tunnel kiln, in which the
bricks are fired as they move slowly through the kiln on conveyors, rails, or kiln cars, which
achieves a more consistent brick product. The bricks often have lime, ash, and organic matter
added, which accelerates the burning process.
Dry pressed bricks (slide 10)
The dry press method is similar to the soft mud brick method, but starts with a much thicker
clay mix, so it forms more accurate, sharper-edged bricks
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