Fired bricks are burned in a kiln which makes them durable. Modern, fired, clay bricks are formed in one of three processes – soft mud, dry press, or extruded.
Normally,
contains the following ingredients:
1.Silica (sand) – 50% to 60% by weight
2.Alumina (clay) – 20% to 30% by weight
3.Lime – 2 to 5% by weight
4.Iron oxide – ≤ 7% by weight
5.Magnesia – less than 1% by weight
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 25–30% 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 fired ("burned") at 900–1000 °C to achieve strength.
Three
basic types of brick are un-fired, fired, and . Each type
is manufactured differently.
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