Building Materials, Third Edition

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u fX The kiln used for burning bricks may be underground, e.g. Bull’s trench kiln or
overground, e.g. Hoffman’s kiln. These may be rectangular, circular or oval in shape. When the
process of burning bricks is continuous, the kiln is known as continuous kiln, e.g. Bull’s trench
and Hoffman’s kilns. On the other hand if the process of burning bricks is discontinuous, the
kiln is known as intermittent kiln.

s #  uX The example of this type of an over ground, rectangular kiln is shown in Fig.
2.10. After loading the kiln, it is fired, cooled and unloaded and then the next loading is done.
Since the walls and sides get cooled during reloading and are to be heated again during next
firing, there is wastage of fuel.

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g%%2uX The examples of continuous kiln are Hoffman’s kiln (Fig. 2.11) and Bull’s
trench kiln (Fig. 2.12). In a continuous kiln, bricks are stacked in various chambers wherein the
bricks undergo different treatments at the same time. When the bricks in one of the chambers
is fired, the bricks in the next set of chambers are dried and preheated while bricks in the other
set of chambers are loaded and in the last are cooled.

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