CE8391 CONSTRUCTION MATERIALS UNIT I STONES – BRICKS – CONCRETE BLOCKS Manufacturing Process of Bricks

1. Presentation by,
Mr. P.SELVAKUMAR.,B.E.,M.E.
Assistant Professor,
Department of Civil Engineering,
Knowledge Institute of Technology,

2.  Preparation of clay
 Moulding of clay
 Drying
 Burning

3. The clay of bricks is prepared in the following order
 Unsoiling
 Digging
 Cleaning
 Weathering
 Blending
 Tempering

4. Unsoiling
 The top layer of soil about 200 mm
in depth is taken out.
 If the clay in topsoil is full of
impurities it will be rejected.

5. Digging
 The clay is then dug out from
the ground.
 It is spread on the levelled
ground.
 The height of heaps of clay is
about 600 mm 1200 mm

6. Cleaning
 The clay which is used for
preparing bricks should be
cleaned of stones, pebbles
and vegetable matter, etc.
 If the impurities are present in
excess the clay is subjected to
washing and screening.

7. Weathering
 The clay is exposed to weather
from few weeks to full season.
 Subjecting the soil to exposed
condition of weather such as
rain, heat by sun, snow,
wind, etc. is known as
weathering.
 Alternate wetting, cooling,
heating and drying.

8. Blending
 The clay is made loose and any
ingredient to be added to it, is
spread out at its top.
 It is carried out by taking small
portion of clay every time and
by turning it up and down in
vertical direction.
 For large quantity of soil
machines may be adopted.

9. Tempering
 In the process of tempering the
clay is brought to a proper degree
of hardness and it is made fit for
the next operation of moulding.
 The water in required
quantity is added to Clay and
just under the feet of men for
cattle.
 The tempering makes the clay into
a homogeneous mass

10. The molding can done in two
ways
 Hand moulding
 Machine moulding

11. Hand moulding
 The bricks or moulded by using
manpower
 It is adopted where the main
power is cheaper
 It is suitable for small scale
production

12. Types of mould
 The moulds for rectangular boxes are open at top and bottom
 Based on the material in which the mould is made it is classified as
 Wooden mould
 Steel mould

13.  Wooden mould
 It should be prepared from well-
seasoned wood
 The longer sides or kept slightly
projecting to serve as handles
 The wood should have smooth
faces

14.  Steel mould
 Steel mould are made by the Steel plates
or channels.
 The thickness of Steel mould is generally
6mm.
 The Steel moulds are more durable than
wooden moulds.
 It can produce the bricks of uniform sizes
when compared to wooden moulds.

15. The bricks prepared by hand moulding are of two types
 Ground moulded bricks
 Table moulded bricks

16.  Ground moulded bricks
 This type of bricks is hand moulded and placed on ground itself
 The process of ground moulding are given below
 Leveling the ground and sprinkling the fine sand over it
 over it the mould is dipped in water and placed over the ground
 The lump of tempered clay is filled in the mould
 the clay is pressed until fill all the corners of mould
 the extra clay is removed by wooden or metal Strike
 the mould is then lifted up and raw brick is left on the ground

17.  Ground moulded bricks
 Usually the ground moulded
bricks or rough at the bottom
surface. Hence it is placed on
sprinkling sand it is also called
as sand moulded bricks
 A brick moulder can mould
about 750 bricks per day

18.  Table moulded bricks
 This type of bricks are hand
molded and it is placed on table
 A table of size about 2 m x 1 m is
used.
 The process of moulding this
breaks is just similar to ground
moulded bricks
 Generally the table moulded
bricks are having smooth
surface at bottom

19.  Machine moulding
 Machine moulded bricks are usually wire cut and pressed bricks.
 It having smooth surfaces, regular shape, Sharp edges and corners
 They are heavier and stronger than ordinary hand moulded bricks
 The Machines or broadly classified into two categories
 Plastic clay machines
 dry clay machines

20.  Plastic clay machines
 Water is added to make the clay in
plastic state
 This machine consist of rectangular
opening of size equal to width of
the bricks
 The pug clay is placed in the
machine and it comes out through
the opening, it is cut into to strips
bye wires fixed in frames
 Arrangement is made in such a way
that, the wire cutting is equal to the
length of bricks

21.  Dry clay machines
 In this machines the strong clay
is first converted into powdered
form
 A small quantity of water is then
added to get a plastic paste
 Search paste is placed in mould
and pressed by the machine to
form hard and well-shaped
bricks

22.  Drying is usually done by placing the bricks in sheds with open sides so as to
ensure free circulation of air and protection from bad weather and rains.
 The bricks are allowed to dry till they are left with 5 to 7 percent moisture
content.
 The drying period usually varies from 7 to14days.
 The moulded bricks are dried because of the following reasons.
 If damp bricks or green bricks are directly taken to burning then, they are likely to be
cracked and distorted
 To remove maximum moisture from the brick
 to save time and fuel during burning
 To increase the strength of raw bricks so that they can be handled and stacked in greater
heights.

23.  It is the very important step in manufacture of bricks. Bricks may be
burnt by two distinct methods given below.
 Clamp burning
 Kiln burning

24.  Clamps
 In clamps, one batch of green
bricks is heaped along with
firewood, coal etc. and sealed
with clay. It is then fired slowly
to intense heat which may take
many days.

25.  Kilns
 It is a permanent structures consisting
of many chambers.
 There are intermittent and continuous
kilns.
 Moulded clay is stacked in the
chambers. They are then slowly dried
and burned to high temperature and
cooled.
 One cycle of loading, drying, burning,
cooling and emptying may take as
much as two weeks.
 These processes are carried out
intermittently in intermittent kilns
and in cyclic order in continuous
kilns.