How Bricks are made ?

Bricks are used extensively in construction at all levels, from thatched roofs to multi-story buildings. Except for slight changes, the brick-making technique has remained unchanged for many years. Bricks are the oldest building material that is still widely used today due to their durability, availability, and low cost. Building quality has greatly increased as a result of refined brick production and burning procedures.

                     

Brick manufacturing

The manufacturing procedures vary greatly depending on the type of clay used, the machinery available, and so on, and the following is a quick basic overview. Bricks are formed using either technology or by hand.

Bricks produced by machine

The majority of bricks are manufactured by machinery. The various stages are as follows: 1.Earth preparation, 2.moulding, 3.drying. 4.burning.

 

1.     Earth preparation - After extracting the clay or shale and removing large stones or other unwanted debris, it is carried to a granulator and finely processed by massive spinning wheels that force it through small perforations in the mill's bottom.

Moulding- There are two types of machine-made bricks: wire-cuts and pressed bricks.

Wire-cuts Bricks are formed in the following ways: The fine clay from the pug mill is driven through a mouthpiece (about 215mm by 102.5mm) of a continuous band machine and carried by rollers to a frame with several fine vertical wires spaced 65mm apart. A part of this continuous band, equal in length to the frame, is forced forward through the frame by a metal plate, and wires separate it into ten or more 215mm by 102.5mm by 65mm clay slabs.

Pressed Bricks- Of the many various types of machines for pressing bricks, the smallest is operated by hand and the largest by steam power. The former consists of a metal box the size of a brick enclosing a wire-cut clay slab as described above. A descending metal plate applies pressure on the clay to consolidate it before it is removed.

The larger machine is made out of a spinning table with twelve or more boxes or dies, each the size of a brick. As the table rotates, each die is carried under the hopper containing the prepared clay or shale, a pusher in the bucket descends and forces the clay into the die, and raw brick (or slab of clay) is pused out as the table turns.

Drying and Burning

Both of these activities are performed in a modern kiln, one type of which has numerous chambers, each of which may hold 40,000 or more pounds and is laid out in alternate layers at right angles to each other. Heat from gas or coal dust is gradually added until the maximum temperature is reached (which is maintained for about two days), at which point the bricks are allowed to cool. The loading, drying, burning, cooling, and emptying of the kiln can take up to two weeks, and because it is a continuous process, the finished brick chamber is emptied everyday.

 

Firing the bricks

The bricks are ready for fire once they have dried. The temperature of the kiln is determined by the content of the bricks. Kilns typically maintain temperatures ranging from 900°C to 1200°C for each type of brick. The components within the brick form a ceramic bond during the fire process, which hardens the brick and guarantees that it retains its shape. Firing ensures that bricks can withstand extreme weather conditions such as rain, heat, and cold, as well as foot and tyre traffic.

 

Hand made bricks

While most bricks are machine-made and utilised for common uses (because to their low cost), there is also a demand for hand-crafted bricks for superior facing work. The drying and burning techniques for the preparation are similar to those already detailed, but the moulding is done by hand. The mould is made of wood or metal and looks like the sides of a rectangular box the size of the necessary bricks. To prevent the clay from sticking to it, it is either wetted or sanded. The moulder takes a part of the prepared clay sufficient to fill the mould, shapes it roughly, and dashes it into the mould. The clay is squeezed with the fingers to completely fill the mould, and the slab is levelled off with a wood fillet or a piece of wire stretched across the top. The slab is then removed and directed and burned in the kiln.

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