Building material, BRICKS as per is codes. it basically covers all the aspects of brick right from manufacturing to finishing and stats to improvement can or needed to be done. This is all u need to go through to understand the concept of bricks. 2k17

1. BRICKS
By: MOHIT

2. HISTORY OF BRICKS
The bricks seem to have been produced since the dawn of the civilization in the
sun-dried form. The Great Wall of China (210 B.C.) was built with both, burnt
and sun-dried bricks. The other examples of the use of bricks in early stage of
civilization could be cited in Rome and other places.
The medieval cities were of wood and
because of the disastrous fire potential of wood; the bricks replaced the wood
over the years. For instance, the great fire of London in 1666 changed London
from being a city of wood to one of brick. A number of country farm houses still
exists in Great Britain and profess to be monuments of the excellent hand-
made bricks.

3. BRICK INDUSTRY IN INDIA
Fired clay bricks are one of the most important building materials in India.
India is the second largest producer of bricks, accounting for over 10% of the
global production. It is estimated that India has more than 100,000 brick kilns
producing about 250 billion bricks annually. The Gangetic plains of North
India comprising the states of Assam, Bihar, Haryana, Punjab, Uttar Pradesh
(UP), and West Bengal account for about 65% of the total brick production of
India, whereas peninsular and coastal India contribute the remaining 35%. Th
e fringe areas of cities in this region are dotted with large clusters of brick
kilns. Figure 1 shows the process of clay-fired brick manufacturing.

4. STANDARD SIZE OF INDIAN BRICK
In India, the Red Brick is termed as Common Brick which is made
of burning clay in brick kilns. The standard size as recommended
by the Bureau of Indian Standards
IS:2691:1988 Revision 2 “ Burnt Clay facing bricks specification”
sub-clause. 4.1 & 4.2 of Clause. 4 of page.1 is
190 mm X 90 mm X 90 mm. The IS code also states that with
mortar thickness added, the brick size shall be
200 mm X 100 mm X 100 mm.

5. MODULAR SIZE OF BRICK
Practically to match with the beam width a brick or block of
width 230 mm is used widely in construction industry. The
115 mm is considered for half brick. The size 230 mm X 110
mm X 110 mm or 230 mm X 110 mm X 75 mm is generally
used in construction industry.

6. FROG
• An indent on one surface of longer side
is called Frog, the depth of Frog shall
be 10–20 mm, and the size of shall be
10 X 40 X 10 cm. The purpose of
providing frog is to hold the mortar.
The side of frog is considered as Top
surface. It is not provided in the 40
cm high bricks and extruded bricks.

7. COMPOSITION OF GOOD BRICK MATERIAL
• Alumina: It is the chief constituent of every kind of clay. A good brick should contain
20% to 30% of alumina. This constituent imparts plasticity to the clay so that it can
be moulded. If alumina is present in excess, with inadequate quantity of sand, the
raw bricks shrink and warp during drying /burning and become too hard when
burnt.
• Silica: It exists in clay either as free or combined. As free sand, it is mechanically
mixed with clay. In combine form, it exists in chemical composition with alumina. A
good brick material should contain about 50% to 60% of silica. The presence of this
constituent prevents cracking, shrinking and warping of raw bricks. It thus imparts
uniform shape to the bricks. The durability of bricks depends on the proper
proportion of silica in brick material. The excess of silica destroys the cohesion
between particles and the bricks become brittle.

8. • Lime: A small quantity of lime not exceeding 5 percent is desirable in good brick material. It
should be present in a very finely powdered state because even small particles of the size of a
pin-head cause flaking of the bricks. The lime prevents shrinkage of raw bricks. The sand
alone is infusible. But it slightly fuses at kiln temperature in presence of lime. Such fused
sand works as a hard cementing material for brick particles. The excess of lime causes the
brick to melt and hence its shape is loss.
• Oxide of iron: A small quantity of oxide of iron to the extent of about 5 to 6 percent is desirable
in good brick material. It helps as lime to fuse sand. It also imparts red colour to the bricks.
The excess of oxide of iron makes the bricks dark blue or blackish. If, on the other hand, the
quantity of iron oxide is comparatively less, the bricks will be yellowish in colour.
• Magnesia: A small quantity of magnesia in brick material imparts yellow tint to the bricks and
decreases shrinkage. However, excess of magnesia leads to the decay of bricks.

9. QUALITIES OF GOOD BRICKS
The bricks should
be table-mounted,
well burnt in
kilns, copper-
coloured, free
from cracks and
with sharp &
square edges. The
colour should be
uniform and
bright.
The bricks should
be uniform in
shape and should
be of standard
size.
The bricks should
give a clear
metallic ringing
sound when
struck with each
other.
The bricks when
broken or
fractured should
show a bright
homogeneous and
uniform compact
structure free
from voids.
The bricks
shouldn’t absorb
water more than
20 percent by
weight for first
class bricks and
22 percent by
weight for second
class bricks, when
soaked in cold
water for a period
of 24 hours.
No brick should
have the crushing
strength below 5.5
N/mm2.

10. HARMFUL CONSTITUENTS IN BRICKS
Kankar and Lime
Stone: Due to presence
of Kankar and lime
stone particles of bricks
are not fluxed and brick
may split up into pieces.
1
Organic Matter: Due to
presence of organic
matter brick do not burn
properly which make the
brick more porous.
2
Pebbles: It prevents
uniformity in brick.
3
Iron Pyrites: Due to
presence of iron pyrites
the bricks are
decomposed and
crystallization of iron
can take place during
burning.
4
Alkali: Due to presence
of alkali materials brick
may absorb water from
atmosphere and
efflorescence in brick
may occur which
decreases the strength of
brick work and provide
unhygienic conditions
for the residents.
5

11. BRICK MAKING PROCESS
 Mining of clay
 Preparation of wet clay mix
 Moulding of brocks
 Drying
 Firing

13. BRICK MAKING IN INDIA
• Hoffman’s kilns are continuous domed kilns invented in Germany. They have a permanent
arched masonry and tall chimney. The circular arched tunnel surrounding the chimney has
various chambers where green bricks are placed and the fuel is added via vents in the roof.
• The Bull Trench Kiln (BTK), which is very popular in the Indian sub continent, is an arch-less
modification of the Hoffman’s kiln. It is circular or elliptical in shape. Bricks to be fired are
arranged in a trench and tall movable metal chimneys are placed on the brick setting. They are
moved as the firing progresses. There are also modifications of the BTK which have a permanent
fixed chimney.
• Habla Zig-Zag Kiln is also a German invention. It is an automated tunnel kiln. This one has a
fire zone moving through a stack of stationary bricks. The fire moves with the help of an axial
fan. The bricks are arranged such that hot flue gases move between them in a zig-zag manner
resulting in better heat utilisation and energy efficiency.

14. • Tunnel Kiln. The principle is to move green bricks through a stationary fire. It is energy intensive
and generally used in developed countries. It is essentially a 50-100 ft long rectangular chamber
lined with high quality refractory bricks. The bricks are loaded from one end in a car at a
predetermined pattern. After a fixed interval of time, depending on the firing cycle, a car is
pushed from one end, simultaneously taking one car out from the other end of the tunnel.
• The Vertical Shaft Brick Kiln (VSBK) is a Chinese technology based on the traditional updraft
intermittent kiln. The kiln consists of one or two shafts in a rectangular structure insulated with
agriculture residue and clay. The shaft is loaded from the top in a pre determined pattern. After
being fired in the shaft they are removed batch wise from the bottom via an unloading tunnel. It
is well suited to the context of the South Asian brick sector.
• Clamp. The clamp is the most basic type of kiln since no permanent kiln structure is built. It
consists essentially of a pile of green bricks interspersed with combustible material. The green
bricks are generally piled up on a thin bed of fuel (usually in case of coal fired clamps). Where
spreading of fuel in thin bed is not possible (usually in the case of firewood fired clamps), tunnels
are made through the base of the pile in order to feed the fuel.

15. DISTRIBUTION OF
DIFFERENT TYPE
OF KILNS IN INDIA
 Fixed chimney bull`s trench kilan
Moving Chimney bull`s trench kilan
 Fixed chimney clamp
 Moving Chimney clamp
 Hoffmann kiln

16. FIXED CHIMNEY BULL’S
TRENCH KILN: INEFFICIENT
AND POLLUTING

17. As mentioned earlier, FCBTK is a continuous, moving fi re kiln operated under a
natural-draught provided by a fixed chimney. Initially, BTKs had movable metallic
chimneys. Movable metallic chimneys were banned through an MoEF notifi cation
in 1996. Since then, most BTKs have changed over to fi xed chimneys. Box 1
provides the details of the transition process of moving chimney kilns to FCBTK.
Th e conversion to FCBTK technology reduced the SPM emissions as well as fuel
use compared to the moving chimney BTK. However, FCBTK also suff ers from
incomplete combustion of fuel, indicated by high CO concentration in fl ue gas
(PPM range), black smoke, and unburnt coal deposition at the fl oor of the kiln. Th
e incomplete combustion of fuel results in high SPM and BC emissions in fule
gases. Th e measured SPM emissions from FCBTK1 lie in the range of 150–1250
mg/Nm3.

20. ZIGZAG FIRING TECHNOLOGY:
A WIN–WIN OPTION TO
REPLACE FIXED
CHIMNEY BULL’S TRENCH KILN

21. The Zigzag kiln is an improved version of the FCBTK. Th e main
innovation is in the arrangement of bricks. In a Zigzag kiln, the bricks
are arranged in such away that the air is forced to follow a zigzag
path. Th e main diff erences between an FCBTK and a Zigzag kiln are
listed below.

22. 1. In a Zigzag kiln, the air moves in a zigzag path whereas in an FCBTK, the movement of air is
in a straight path . Th e length of the zigzag air path is about three times longer than the
straight-line air path. Th e increased air velocities in the kiln, the turbulence created due to the
zigzag air movement, and the longer air path result in improved heat transfer between air/fule
gases and bricks.
2. In a Zigzag kiln, powdered coal is fed in small quantities and the fuel feeding zone is six times
longer than that of FCBTK. Th e longer fuel feeding zone, the smaller size of coal particles, and
the turbulence created by the zigzag air movement all help to better mix the coal volatiles with
air, thereby resulting in more complete and cleaner combustion of coal.
3. An FCBTK is oval or circular in shape, while a Zigzag kiln is rectangular in shape.

23. 10/29/2017Sample Footer Text 23

25. HOFFMANN KILN

26. The Hoffmann kiln is a series of batch process kilns. Hoffmann kilns are the most common kiln used
in production of bricks and some other ceramic products. Patented by German Friedrich Hoffmann for
brickmaking in 1858, it was later used for lime-burning, and was known as the Hoffmann continuous
kiln.
A Hoffmann kiln consists of a main fire passage surrounded on each side by several small rooms. Each
room contains a pallet of bricks. In the main fire passage there is a fire wagon, that holds a fire that
burns continuously
Each room is fired for a specific time, until the bricks are vitrified properly, and thereafter the fire
wagon is rolled to the next room to be fired. Each room is connected to the next room by a passageway
carrying hot gases from the fire. In this way, the hottest gases are directed into the room that is
currently being fired. Then the gases pass into the adjacent room that is scheduled to be fired next.
There the gases preheat the brick. As the gases pass through the kiln circuit, they gradually cool as
they transfer heat to the brick as it is preheated and dried. This is essentially a counter-current heat
exchanger, which makes for a very efficient use of heat and fuel. This efficiency is a principal
advantage of the Hoffmann kiln, and is one of the reasons for its original development and continued
use throughout history. In addition to the inner opening to the fire passage, each room also has an
outside door, through which recently fired brick is removed, and replaced with wet brick to be dried
and then fired in the next firing cycle.

27. 10/29/2017Sample Footer Text 27

29. VERTICAL SHAFT BRICK
KILN TECHNOLOGY

30. VERTICAL SHAFT BRICK KILN TECHNOLOGY
Vertical shaft brick kiln (VSBK) is a continuous, updraft, moving ware kiln in which the fire
remains stationary while there is counter current heat exchange between air (moving upward) and
bricks (moving downward). The VSBK technology has evolved from the traditional up-draught
kilns in rural China. during late 1950s; however, the widespread dissemination of the technology
took place after the economic reforms.
At its peak during the mid 1990s, thousands of VSBKs were reported to be
operating in China. Since 1990, under different technology transfer projects the technology has
been transferred to several developing countries including India, Nepal and Vietnam. Whereas the
dissemination of VSBK technology in India and Nepal has been relatively slow, the experience in
Vietnam has been very positive. Vietnamese brick makers have been able to innovate and have
added new features to the technology, and in the process have transformed a rural technology into
an industrial technology.

31. 10/29/2017Sample Footer Text 31

33. TUNNEL KILN

34. Tunnel kiln is a continuous moving ware kiln in which the clay products to be fired are passed on cars
through a long horizontal tunnel. The firing of products occurs at the central part of the tunnel. The
tunnel kiln is considered to be the most advanced brick making technology.
The main
advantages of tunnel kiln technology lie its ability to fire a wide variety of clay products, better control
over the firing process and high quality of the products. The tunnel kiln technology was developed
around mid 19th century in Germany. However, the application of the technology for brick firing took
place in the 20th century. After the Second World War, the technology was widely adopted and led to
the transformation of the European brick industry from several thousand small and scattered brick
making units into a few hundred large scale and highly mechanized tunnel kiln units. In Asia, China
and Vietnam started adopting the technology during the 1970’s and now have several hundred tunnel
kilns in operation. In India, there are very few (~5) tunnel brick kiln units.

37. CLAMP

38. The clamp is the most basic type of kiln since no permanent kiln structure is built. It
consists essentially of a pile of green bricks interspersed with combustible material. The
green bricks are generally piled up on a thin bed of fuel (usually in case of coal fired
clamps). Where spreading of fuel in thin bed is not possible (usually in the case of firewood
fired clamps), tunnels are made through the base of the pile in order to feed the fuel. In an
improved version of clamp, the outer walls are plastered (scoved) with mud to reduce the
heat loss and thus are termed as Scove kiln. The other improvement is Scotch kiln in which
the base, fire tunnels and outer walls are permanently built with bricks. In this factsheet,
all these variations are referred as clamps. Till the end of 18th century, bricks were almost
exclusively fired in clamps. However, with the introduction of continuous kilns and
mechanisation, clamps were gradually phased out from the developed countries, but these
are still prevalent in developing countries.

41. INTERNATIONAL SCENARIO
Replacement with REBs (perforated bricks, hollow bricks, bricks with internal fuel/ flyash bricks
etc).
Mechanization for clay preparation and molding
Min. 20-30% savings in fuel and clay.
In China, upto 80% of total fuel requirement mixed as internal fuel and remaining 20% fuel used
during firing process – Emission reduction from kiln to a large extent.
USA/ Europe – Natural gas fired Tunnel Kilns High Initial cost (5-10 crores)
Lack of Know-how
Access to finance
Hot environment inside Hoffman
kiln
China – Tunnel/ Hoffman Kiln
Vietnam – Coal fired Tunnel Kilns
Bangladesh – Hybrid Hoffman Kiln/ Tunnel
Kiln

42. BRICK PRODUCTION IN ASIA
Bangladesh India Vietnam Nepal Pakistan China
No. of brick
units
------- 1,40,000 10,000 700 >10,000 80,ooo
Production in
billion
17.2 240-260 26.59 3.15 50 800-1000
Labor in '000 1000 9,000 NA NA 1500 5000
Population in
million
149.7 1210 176.5 18.6 176.7 1334
Brick use/
capita
115 215 151 169 283 750

43. INDIAN BRICK INDUSTRY
• Annual brick production growth: 5-10%
• •2nd largest brick producer after China.
• •74% of total production through BTKs and 21% through Clamps (100K).
Brick-making enterprises (all types)(no.) 1,40,000
Brick-making fuel used Coal & biomass
Annual brick production 240-260 billion
Coal/biomass consumption (million tce) 35-40
CO2 emissions (million t) 66
Clay consumption (million m3) 500
Total employment (million employees) 9-10

44. TOWARDS
CLEANER BRICK
KILNS IN INDIA

45. EMISSION STANDARDS FOR BRICK KILNS BY MOEF (MINISTRY
OF ENVIRONMENT, FOREST AND CLIMATE CHANGE)

46. RETROFITTING OF FCBTKS INTO ZIGZAG KILNS:
A WIN–WIN PROPOSITION
Most of the FCBTKs can be retrofitted into natural or high-draught Zigzag kiln.
The cost of retrofitting varies from Rs 10 lakh to Rs 25 lakh (Rs 1 million to Rs 2.5
million) depending upon the condition of the existing kiln and the extent of
retrofitting required. Retrofitting involves:
partial reconstruction of the chimney and reconstruction of the flue-ducts and the outer wall of
the kiln (Figure 10a).
change from column-blade brick setting in FCBTK to chamber-wise brick setting for Zigzag
(Figure 10b).

47. 10/29/2017Sample Footer Text 47

48. A 20% reduction in energy consumption through retrofi tting of all FCBTKs into Zigzag kilns would
result in an annual saving of approximately 6 MT of coal having a monetary value of Rs 3000–5000
crore.4 Apart from coal savings, it will avoid release of about 455,000 tonnes (T) of SPM, 14 MT of
CO2, and 55,000 T of BC annually into the atmosphere. In order to convert all the FCBTKs to
Zigzag kilns, the capital expenditure is estimated to be of the order of Rs 3000–7500 crore (Rs
30,000–75,000 million).
The conversion from FCBTK to Zigzag kilns benefi ts brick-kiln owners the most. Th e two-fold fi
nancial benefi ts – fi rstly through savings from reduced fuel consumption and secondly by increase
in revenue due to the higher percentage of the highest quality product – make it a fi nancially
attractive proposition. Clay-fi red bricks are locally produced and locally consumed. Th erefore, the
price of bricks and the price differentiation between the quality grades of bricks vary across the
regions. Hence the techno-economics of conversion will vary from one region to the other. Th e
conversion of a typical FCBTK located in eastern UP, Bihar, or West Bengal to Zigzag kiln would
result in doubling the operating profit margin of the kiln. For a new construction, the capital cost of
constructing a Zigzag kiln is equivalent to or in some cases marginally higher than an FCBTK;
however Zigzag kiln yields higher profi t margins. Box 3 provides the success story of a retrofi tted
FCBTK into a natural-draught Zigzag kiln.

53. SPECIFIC ENERGY CONSUMPTION (SEC)
IN MJ/ KG OF FIRED BRICK
FCBTKs-Coal fired 0.95 – 1.82
FCBTK-Biomass fired 1.33 – 1.95
HDKs/FCBTK zig-zag 0.91 – 1.15 Better operating practices
VSBK 0.90 Limited brick production and high
initial cost
Hoffman Kiln 1.21 – 1.52 Produce hollow block, roof tiles
DDKs 2.8 – 3.14
Clamps 1.38 – 1.92

54. PROCESS IMPROVEMENT
• Use of Temperature gauge in firing zone, flue duct and chimney to monitor and control
combustion process.
• Use of double walled insulated feedhole covers packed with insulation material such as ceramic
or asbestos fibers to prevent heat loss from fuel charging holes bull’s trench kilns.
• Double walled wicket with kiln ash filled in between Bull’s Trench Kilns instead of conventional
single brick wicket wall with brick on edge which results in leakage.
• Closing of side flue ducts with brick wall (1 ½ brick thick) plastered with a mix of sand clay and
cow dung bull’s trench kilns or alternatively, shunt system should be used for transferring the
gas from side flues to central flue, connected with chimney.
• Minimum 7 inch thick brick kiln ash layer over the brick setting bull’s trench kilns to provide
heat insulation.
• Placement of fuel in multi-layers during brick stacking in clamp kilns to reduce emissions and
to produce better quality bricks

55. PROCESS TECHNOLOGY

56. Nature of processing
method
Requested number of
workers for producing
1 million standard
bricks per year
Number of
standard bricks
per worker per
year
Purely manual 20 50 000
Partially mechanized 14 71 400
Fully mechanized 6 166 700
Semi-automatic 1 1 000 000
Automatic 0.25 4 000 000
THE LINK BETWEEN PROCESS
TECHNOLOGY AND PRODUCTIVITY

57. TYPES OF
BRICKS
Sun-Dried or Unburnt Bricks
Burnt Bricks
First class bricks
Second class bricks
Third class bricks
Fourth class bricks

58. UNBURNT BRICKS
• Sun-dried or unburnt bricks are less durable and these are used for temporary
structures. Unburnt bricks preparation involved in 3 steps they are preparation of
clay, molding and drying. After molding, bricks are subjected to sunlight and dried
using heat from sun. So, they are not that much strong and they also have less
water resistance and less fire resistance. These bricks are not suitable for
permanent structures.

59. FIRST CLASS BRICKS
• First class bricks are good quality bricks
compared to other classes. They are
molded by table-molding and burnt in
large kilns. So, these bricks contain
standard shape, sharp edges and smooth
surfaces. They are more durable and
having more strength. They can be used
for permanent structures. However,
because of their good properties they are
costly than other classes.

60. SECOND CLASS BRICKS
• Second class bricks are moderate quality
bricks and they are molded by ground-
molding process. These bricks are also
burnt in kilns. But because of ground
molding, they do not have smooth
surfaces as well as sharp edges. The
shape of bricks also irregular due to
unevenness in ground. These also will
give best results in strength and
durability. Smooth plastering is required
on the brick structure.

61. THIRD CLASS BRICKS
• Third class bricks are poor quality
bricks which are generally used for
temporary structures like unburnt
bricks. These are not suitable for rainy
areas. They are ground-molded type
bricks and burnt in clamps. The
surface of this type of bricks are rough
and they have unfair edges.

62. FOURTH CLASS BRICKS
• Fourth class bricks are very poor
quality bricks and these are not used
as bricks in the structure. They are
crushed and used as aggregates in the
manufacturing of concrete. They are
obtained by over burning, because of
this they gets overheated and obtains
brittle nature. So, they can break
easily and not suitable for construction
purpose

63. IDENTIFICATION OF BRICKS QUALITY AT
CONSTRUCTION SITE
The color of bricks should be bright and uniform.
They should be well burned and having smooth surfaces and sharp edges.
Thermal conductivity of bricks should be less and they should be sound proof.
They shouldn’t absorb more than 20% by weight when we placed it in water.
When we struck two bricks together, ringing sound should be delivered.
Structure of bricks should be homogeneous and uniform.
The bricks should not break when we dropped it form 1m height.
There should not be any scratch left on the brick when we scratched with finger nail.
There should not be any white deposits on brick, when we soaked it in water for 24 hrs.

64. PROPERTIES OF BRICKS
• Following are the properties of bricks which represents the importance of bricks in
construction.
i. Hardness
ii. Compressive strength
iii. Absorption

65. HARDNESS OF
BRICKS
• A good quality brick will have resistance against abrasion.
This property is called hardness of brick which helps to give
permanent nature of brick structure. Because of this property
bricks do not damaged by scraping.

66. COMPRESSIVE STRENGTH OF BRICKS
Compressive strength or crushing strength is the property of brick which represent
the amount of load carried by brick per unit area. According to BIS the minimum
compressive strength of brick should be 3.5N/mm2. Crushing strength of bricks
reduced when they are soaked in water
• First class bricks— 105 kg/sq. cm.
• Second class bricks—70 kg/sq. cm,
• Common building bricks—35 kg/sq. cm,
• Crushing strength of bricks not less than 140 kg/sq. cm are graded as AA class.

67. WATER ABSORPTION
Class of brick Water absorption
Heavy duty bricks (special made) Only 5%
First class 20%
Second class 22%
Third class 25%
Bricks are generally absorbs water but having limits. Absorption limit
percentage by weight for different classes of bricks is tabulated below.

68. RATE OF BRICKS
• First class brick ---------- Rs. 4.6/unit
• Second class brick--------- Rs. 3.6/unit
• Third class brick------------Rs. 3.2/unit
• Fourth class----------------- Rs. 3.0/unit

69. USES OF DIFFERENT TYPES OF BRICKS
Good quality bricks (1st and 2nd class) are used in the construction of buildings,
tunnels, pitching works etc.
3rd class and unburnt bricks are used for temporary structures.
4th class bricks are used as aggregate for making concrete.
Bricks are also used for architectural purposes to give aesthetic appearance to the
structure.

70. FLY ASH BRICK
Fly ash brick (FAB) is a building material,
specifically masonry units, containing class C or class F fly
ash and water. Compressed at 28 MPa (272 atm) and cured
for 24 hours in a 66 °C steam bath, then toughened with an
air entrainment agent, the bricks last for more than 100
freeze-thaw cycles. Owing to the high concentration
of calcium oxide in class C fly ash, the brick is described as
"self-cementing". The manufacturing method saves energy,
reduces mercury pollution, and costs 20% less than
traditional clay brick manufacturing. Ever since FaL-G (Fly
ash-Lime-Gypsum) process is introduced in 1991, fly ash
brick activity has been revolutionised in India.

71. RAW MATERIAL FOR FLY ASH
The strength of fly ash brick manufactured with the above compositions is normally of the order of
7.5 N/mm2 to 10 N/mm2. Fly ash bricks are lighter and stronger than clay bricks.
Main ingredients include fly ash, water, quicklime or lime sludge, cement, aluminum powder and
gypsum. The block hardness is being achieved by cement strength, and instant curing mechanism
by autoclaving. Gypsum acts as a long term strength gainer.
Material Mass
Fly ash 60%
Sand/stone dust 30%
Ordinary Portland Cement
(Lime+Gypsum)
10%

72. ADVANTAGES
• It reduces dead load on structures due to light weight (2.6 kg, dimension: 230 mm X 110 mm X
70 mm).
• Same number of bricks will cover more area than clay bricks
• High fire Insulation
• Due to high strength, practically no breakage during transport and use.
• Due to uniform size of bricks mortar required for joints and plaster reduces almost by 50%.
• Due to lower water penetration seepage of water through bricks is considerably reduced.
• Gypsum plaster can be directly applied on these bricks without a backing coat of lime plaster.
• These bricks do not require soaking in water for 24 hours. Sprinkling of water before use is
enough.

73. CONCLUSION
India is the second largest producer of clay-fired bricks in the world with an annual
production of about 250 billion bricks. Brick kilns consume a large amount of coal and
are an important source of air pollution in the country. About 70% of the brick production
in the country takes place through the 30,000 brick-making units that are based on
FCBTK technology. Retrofitting of the FCBTKs into Zigzag-firing technology off ers a
win–win opportunity not only for brick-makers (by doubling their profits) but also for the
nation leading to annual savings of 6 MT of coal and abatement of 455,000 T of SPM, 14
MT of CO2, and 55,000 T of BC. Policy and regulatory measures at central and state
levels, coupled with an effective technology delivery system linked with access to finance,
can play a crucial role in the dissemination of Zigzag-fi ring technology. Th e changeover
to Zigzag kilns could be the first step towards modernizing the brick industry in India.

74. END OF
PRESENTATION