Civil Engineering Reference
In-Depth Information
Figure 8.7: The industrial die with mouthpiece.
just knocking the clay by hand into a mould. Mechanical hand presses are also
used.
The industrial die presses out the clay through a mouthpiece as a long sausage
with a cross-sectional area allowing for shrinkage (see Figure 8.7). Different sizes
of mouthpiece and square or round pegs form holes in the clay sausage. Roof
tiles can also be produced in this way. The sausage is cut into blocks on a bench.
Mobile dies also have equipment to prepare the clay before pressing, and are
used where there are smaller deposits of clay.
Handmade bricks are made by placing the clay into wooden or metal
moulds in the same way as earth blocks, and striking with a piece of wood (see
Figure 8.8). The moulds are sprinkled with sand or dipped in oil or water
between strikings. A 'brickstriker' and two assistants can produce 2000 ordi-
nary bricks, 1200 flat roof tiles, or 600 profiled tiles in a day. Even if machine-
cut bricks are considerably more economical, the handmade brick with its rus-
tic character is more attractive as a facing brick. As recently as 1973 it was esti-
mated that 99 per cent of all bricks produced in India were handmade (Spence,
1974).
Drying
The unfired brick products are stacked for drying under an open roof for one to
two months. For all-year-round manufacturing, bricks need to be stacked inside.
This increases energy consumption a good deal, as storage rooms need to be very
