This document discusses different types of bricks used in construction. There are four main types classified based on their manufacturing process: ground moulded, table moulded, machine moulded, and pressed bricks. Bricks are further classified according to their intended use, physical properties, and Indian Standards specifications. Various tests are described to evaluate properties like compressive strength, water absorption, efflorescence, dimensional tolerance, hardness, and soundness. Lightweight bricks and brick substitutes using industrial waste materials are also covered.

1. Classification of Bricks

2. Types of Bricks
 Wired-cut bricks
 Pressed bricks
Four types of brick in the market
1. Ground moulded bricks fired in temporary
clamps. Dimensions of bricks are not regular.
2. Table moulded bricks fired in kilns and also
called stock bricks.
3. Machine moulded bricks fired in continuous kilns
and also known as wire cut bricks.
4. Pressed bricks made under pressure. These
bricks are used of decorative works.

3. Dimensions of
Bricks
 Bricks are made in
traditional size and also in
metric size prescribed by
Bureau of Indian Standards.
 Depression made at the top
of a brick is called “FROG”.
 Brickwork constructed with
the frog laid facing upwards.
 It is a key to the mortar to
bond bricks together.

4. Weight of Brickwork
 Deadweight 18 to 19 kN/m3
 Average weight 3 to 3.5kg depending on its
denseness.
 Lightweight hollow bricks can be as low in weight
as only 1/3 the weight of a common brick.

5. Storing of Bricks
 They are not stored for long periods, usually used up in
construction as soon as they delivered at site.
 Each truckload should be piled in separate stacks on
the ground.
 It should be stored in covered sheds during rainy
season for weak bricks.

6. Bricks for special use
1. Facing bricks
2. Fireclay bricks
3. Acid – Resisting bricks
4. Forsterite bricks
5. Silicon carbide bricks

7. Light – weight bricks
 In tall buildings, to reduce the deadweight of walls and
thus, reduce the load on the foundation.
 In partition walls, to reduce weight and insulate them
from sound.
 In walls above cantilever beams to reduce the weight.
It can be made using by any one of the following
methods,
 As solid bricks made from clay mixed with
combustible materials which burn off during leaving a
porous, light brick the fire.
 Hollow bricks contains hollow with ribs. Usually made
from tile clay as the ribs have to be thin and strong.

8. Brick Substitutes
 As bricks made from clay excavated from earth,
availability of good brickearth is less. So it is
necessary to produce bricks from industrial waste
or other raw materials.
Flyash bricks
Sandlime bricks (or) Calcium silicate bricks
Cement and Concrete blocks

9. Flyash Bricks
•Made from flyash which
is a raw materials from
burning of coal or lignite
from various industries
especially in power
house.
• Lime or cement is also
added to give the bricks
required strength.
•Government also
encourages this use of
the waste product by
giving concessions in its

10. Silicate bricks
 Made by autoclaving sandlime bricks (sand, lime,
water and pigments for colour) with high pressure
steam in special chambers.
 High energy cost

11. Classification of bricks
 Mainly classified according to their use, physical
requirements and I.S classification
According to their use
Common bricks
Engineering bricks (Bricks carrying heavy
loads)
Fire bricks
Specials (Special shapes)

12.  According to general physical requirements
Class I Class II Class III
General
requirements
Uniform color,
thoroughly
burnt,
rectangular
faces with
parallel sides
and sharp
straight right
angled edges,
compact and
uniform
texture.
Uniform
colour, and
maybe slightly
overburnt.
Bricks are
slightly
distorted and
have round
edges. Fine
compact and
uniform
texture.
maybe slightly
overburnt or
overburnt.
Distorted and
have round
edges.
Defects in
uniformity and
shape
Water
absorption
Not more than
20% by
weight
Not more 22%
by weight
Not more than
25% by
weight

14. I.S classification of bricks according
to strength
Class
Designation
Compressive
strength
Additional
requirements
10 10 N/mm2 Dimensional
tolerance _+ 3%,
Surface must be
smooth, Should
have a ringing
sound.
7.5 7.5 N/mm2 Dimensional
tolerance _+ 8%,
5 5.0 N/mm2 Dimensional
tolerance _+ 8%,
3.5 3.5 N/mm2 Dimensional

15. Tests for bricks
Compressive Strength
 Five bricks are taken at random and their dimensions
are measured
 Immersed in water of 250C to 290C for 24 hrs.
 Surplus moisture is allowed to drain and the frog, if any,
is filled with mortar 1:3.
 It is kept under a jute bag for another 24hrs after which it
is immersed in clean water for 3 days.
 At the time of testing, these bricks are removed from
water, wiped dry and placed with the flat surface
between plywood sheets each of 3mm thickness.
 This specimen is kept under UTM and load is applied.
 The compressive strength should note down.

16. Water absorption
 Five bricks taken for test. They are allowed to dry
in an oven at 1100C to 1150C till they attain a
constant weight usually takes place in 48 hrs.
 Then they are cooled at room temperature, which
generally takes 4 to 6hrs without a fan and weight
W1 is measured.
 Then they kept in clear water at 290C for 24 hrs
and wiped dry with a damp cloth and weight W2 is
measured.
 The average percentage of water absorbed as
percentage of dry weight is reported.

17. Efflorescence
 Five samples are taken and the bricks are placed
vertically in a dish 30cmX20cm approximately in size
with 2.5 cm immersed in distilled water.
 The water is allowed to be absorbed by the brick and
evaporated through it.
NIL – there is no perceptible deposit of salt.
Slight – Not more than 10% of the area of brick is
covered with salt
Moderate – heavy deposit covering upto 50% of the
area of the brick
Heavy – Heavy deposit covering more than 50% of the
area of the brick.

18. Dimensional tolerance:
 Bricks are selected at random to check
measurement of length, width, height.
 Variations in dimensions are allowed only within
narrow limits, -+3% for class one and -+8% for
other classes
Hardness:
 A scratch is made on the surface of the brick with
the finger nail. In good brick, no impression will
be left on he surface.
Soundness :
 Two bricks are taken, one in each hand and they
are struck with each other slightly. A clear ringing
sound should be produced and the bricks should
not get break.