1.0 INTRODUCTION :
Manufacture of clay bricks is perhaps the oldest
industry in the history of mankind. It is reported
that hand-shaped, sun-dried mud bricks were made and
used during the Pre-Pottery Neolithic Period as far
back as 10,000 B.C. Use of mould-box-shaped, sun-dried
and fired bricks started only around 3000 B.C. Since
then, the technology of clay products has made great
strides with respect to both scale and efficiency
of operation. But unfortunately, this has remained
confined to the developed world only, eluding the
developing world almost completely.
Technically, clay bricks fall under the category
of heavy-clay products, forming a major part of the
ceramic industry. Heavy-clay products are those that
are mainly made from a single clay with very little
addition of other raw materials. They are principally
used in structural work. Hence heavy-clay products
like bricks, hollow clay blocks, roof tiles, split
tiles, etc. are often called structural clay products.
For some time now, scientists have been predicting
the dawn of a 'New Stone Age' during the 21st century,
implying that ceramic products will have wide-ranging
applications in high-tech areas during the next century.
This forecast is perhaps based on the present status
of the 'technical / engineering ceramics' industry
Considering the ceramic industry's long and glorious
past on the one hand and bright future on the other,
where does the Indian Clay Brick Industry - which
is very much a part of the ceramic industry - stands
at present? The answer is, it is fighting for its
existence despite enjoying ever-growing demand all
over the country.
Before attempting to look for strategies for the
revival of the dieing brick industry, one must first
consider why the brick is so popular as a building
material and the burning problems faced by the industry.
2.0 BRICK - A WONDER BUILDING MATERIAL :
Brick, i.e. common burnt clay building brick, is
perhaps the only manmade material that has defied
time gracefully ever since it was invented 5000 years
ago. Unlike metals and organic materials, brick weathers
beautifully with time, never giving in completely
to the onslaught of natural agencies working against
it. Also, it is an extremely good thermal insulating
The long-lasting and excellent thermal insulating
property of the brick has earned it an enviable and
indispensable position among today's building materials.
Like cement (i.e. ordinary Portland cement) no alternative
material has yet been able to threaten burnt clay
brick seriously on technical as well as commercial
grounds. In the early eighties, concrete blocks appeared
to replace it as a walling material in metropolitan
and big cities. But they soon lost their charm on
account of improper mixing and curing practices followed
by their manufacturers and the poor 'nailability',
water seepage resistance and insulating properties
of the material. Their use is now mainly restricted
to areas where poor insulating properties are of little
or no consequence, like compound walls, factory /
commercial buildings, the so-called 'low-cost' housing
schemes, etc. Non-availability or unacceptable quality
of bricks or preference for large-scale captive production
(utilizing huge quantities of freely available aggregates
/ filler materials) may also prompt the use of concrete
blocks. Of late, cured mud blocks or soil blocks have
also tried to make a dent into the popularity of conventional
burnt clay bricks. But despite enjoying continued
Government support and being cheaper and more energy
efficient, they could not muster much support from
the end-users due to poor weathering resistance and
difficulty in organizing large-scale production with
consistent quality in one place.
In short, conventional burnt clay bricks are here
to stay, like it or not! This is precisely the reason
why the brick industry is managing to keep itself
alive, despite serious ailments, which threaten its
3.0 PRESENT STATUS OF THE INDIAN CLAY BRICK INDUSTRY
It is estimated that presently there are at least
1,00,000 brick fields in India, each field manufacturing
between 100,000 and 20 million bricks per year. The
industry employs low-technology, manual and inefficient
methods like hand-moulding, sun-drying and open clamp
burning. Since drying is done in the open, bricks
cannot be dried during the rainy season and hence
the industry is mostly seasonal. It operates for 6
to 8 dry months of a year only, from November to June.
The industry is not 'organized' and very few fields
have officially registered themselves as small-scale
industrial units. On the national level, All India
Brick & Tile Manufacturers Federation, New Delhi,
looks after interests of the industry in general,
and its member units in particular. Brick fields are
normally set up on leased-out lands near clay sources.
Simple tools like pickaxes, shovels, baskets, etc.;
hand carts, screens, moulds, arrangement for storage
/ pumping of water and workers' makeshift sheds constitute
the only fixed investment of a brickfield. Owing to
their temporary, low technology and polluting nature,
and total absence of professional management (including
quality control), these units do not enjoy much respect
in the eyes of people and consequently, bricks are
not thought of as an 'industrial' product by the common
man. Only in South India (and at a few places in the
North also), where roof tile plants are very common,
similar technology is used for making wire-cut bricks,
which command reasonable consumer respect.
Silt deposited by rivers, dams, percolation tanks,
etc. and / or surface soil excavated from barren /
uncultivated / hilly lands form the main sources of
supply of clay. Coal, coal ash (i.e. coal cinder),
wood and many agricultural wastes are used as fuels
in the open clamp, where the extent of under / over
burnt bricks varies up to 20 %. Barring few mechanized
/ semi-mechanised units in North and South India,
all other units employ piece-rate contract labour
to carry out the clay winning / preparation, moulding,
drying, firing and material handling operations. Moulders
perform all operations from clay winning / preparation
to drying, while 'Firemen' or 'Kiln Contractors' take
care of the balance jobs. For this work, moulders
are paid up to Rs. 150/- per 1000 bricks and firemen
up to Rs. 125/- per 1000 full-size bricks. A moulder
family of 3 to 4 persons - husband, wife and 1 or
2 helping hands - can mould up to 3000 'full size'
bricks in a day. However, moulder productivity of
1,200 to 1,500 bricks per day is most common. Before
the beginning of every season, moulders and firemen
are 'booked' by paying them hefty advances.
Bricks are counted and sold in multiples of thousand.
Although IS: 1077 -1992 dictates 7.5" x 3.5"
x 3.5" and 7.5" x 3.5" x 1`.5"
as the two recommended sizes for modular bricks, almost
none of the manufacturers adopts either of these sizes.
9" x 4 ¼" x 3" size bricks are
called standard 'full size' bricks, while smaller
ones are known as 'cut size'. 9" x 6" x
4" size bricks, which are of recent origin, are
called 'double' bricks. Double bricks are very popular
in Mumbai, Pune, Nashik, Aurangabad, etc. cities in
Maharashtra. 10" x 5 " x 3" size is
common in the North-East India. The said IS Specification
classifies bricks in 11 classes, from Class 3.5 to
Class 35 with an average minimum compressive strength
varying between 35 and 350 kgf/cm2, respectively.
But most of the bricks made on the Deccan Plateau
( i.e. Central India ) do not even reach the compressive
strength required by the lowest class 3.5. The average
weight of a full size brick is normally 3 kg. A 10
tonne truck accommodates up to 4,000 cut size, 3,000
full size and 2,000 double bricks. The present 'destination'
prices of bricks vary from Rs. 1,000 to Rs. 6,000
per 1,000 nos. all over the country, depending upon
their size, shape, colour and strength. The average
destination price is around Rs. 1,500/- per 1,000
nos. Bricks attract 8 % sales tax and is economically
sold within a radius of about 50 km. Prices of bricks
keep fluctuating throughout the year, reaching their
maximum during the rainy season, when conventional
brick manufacturing activity comes to a halt, and
minimum in December/January when fresh production
floods the market.
4.0 BURNING ISSUES OF THE INDUSTRY :
4.1 Total Dependence on Skilled Moulders :
This is the most serious ailment of the industry
needing urgent attention. In the absence of an affordable
and/or proven alternative, brick manufacturers have
to totally depend upon skilled moulders for their
livelihood. In addition to paying an advance of up
to Rs.20,000/- per moulder family, they have to be
provided with shelter, firewood, etc. and looked after
well. The advance is normally never recovered at the
end of a season. To improve brick quality, if more
stress is laid on clay preparation, the moulders get
less time to mould bricks and the productivity suffers
heavily. If moulding productivity is stressed, clay
preparation gets neglected, resulting in more breakages.
Absenteeism, sickness, physical disability, etc. aggravate
the situation further. The lure of more money from
nearby brickfield owners makes many a moulders forget
the existing contract (including advance) and accept
4.2 Clay Shortage and Rising Fuel Cost :
Suitability of clay and other additives is solely
decided by the trial and error method and no laboratory
testing is ever employed by brickfield owners. Black
cotton ( i.e. montmorillonite) and similar plastic
soils are not considered suitable for brickmaking.
Due to their stickiness, release of wet bricks from
moulds becomes very difficult and pronounced drying
shrinkage results into cracking and breakages.
Lime nodules are another poison to brickmaking. Lime
( i.e. Limestone) dissociates into quick lime (CaO)
and carbon-dioxide (CO2 ) gas on firing. Quick lime
absorbs moisture during brick cooling and expands
suddenly into hydrated lime (Ca(OH)2) causing brick
disintegration or explosion (called 'lime blowing').
These experiences have made brick manufacturers extra
cautious about choosing raw materials. Only sedimentary
( or alluvial) clay or surface soil of reddish, yellowish
or grayish colour is selected for brick making. Clay
souces near big cities get quickly depleted and at
times claly has to be brought in from as far as 30
to 40 km by paying Rs. 1,200/- per truckload. This
increases the raw material cost substantially.
Fuel cost is normally 30 to 50 % of the cost of production.
At places far away from coal mines, like Uttar Pradesh
for example, a truckload of coal costs no less than
Rs. 3,200/-. This implies that the incidence of cost
on transportation is almost twice the cost of the
material being transported, which is quite an absured
situation ! Also, in South India, where firewood is
traditionally used as fuel for burning bricks, its
cost is increasing by leaps and bounds every year.
Although costs of raw material and fuel are going
up day-by-day, consumers are reluctant to pay higher
prices in the same proportion, since the quality of
bricks is not improving at all. This is affecting
the profitability of the brick industry adversely.
4.3 Opposition from Environmentalists and Social
It is often said that nature takes about 1 million
years to make 10 cms of topsoil. Use of this precious
surface soil for brickmaking, though, considered profitable
by both sellers and buyers of the material, destroys
it permanently. This adversely affects the acreage
of cultivable land, the flora and fauna supported
by it and the environment around. Under Minor Minerals
Act, Government charges royalty to brick manufacturers
at the rate of Rs. 14/- per 100 ft3 of clay. This
is expected to take care of the cost of reclamation
of the affected land. However, in practice, the reclamation
cost is tens of thousands of times more than the royalty
being levied. Use of firewood for brick burning, which
leads to large-scale tree felling, and the air pollution
created by the industry in the form of dust, smoke
and odour, also attract stiff opposition from environmentalists.
Incidence of bonded labour, ill treatment meted out
to animals engaged in pugging / material handling,
etc. evokes considerable uproar from social workers.
4.4 Absence of Appropriate Technology :
Except in South India, especially Kerala, use of
moulding machines has not been much of a commercial
success in the country as yet. This has largely been
due to inadequacy of techno-commercial investigation
and lack of proper financial and mental preparation
on the part of entrepreneurs employing mechanization.
Every rupee of fixed investment added into a project
attracts additional repairs and maintenance, depreciation
and interest cost. Unless this additional cost is
offset by a proportionate increase in production,
the cost of production increases. And to maintain
profitability at increased production cost level,
the consumers should be willing to pay more for better
quality bricks. This is not normally so - at least
in the initial stages of the project - leading to
sickness / closure of the unit. Also, most of the
time, selection and application of technology and
machinery is faulty.
In short, three things need be carefully considered
before an investment decision is made :
5.1 Brickmaking Process :
The brickmaking process can be divided into six steps,
namely, clay winning, raw-mix preparation, moulding,
drying, firing and material handling.
Clay is won (i.e. dug) either manually or by using
excavators. For clay preparation, box feeders, roller
crushers, panmills, disintegrators, double shaft 'U'
mixers, etc. are used. Moulding is carried out using
four techniques as given in Table 1 below.
Table 1 - The Four Moulding Techniques
Typical water content in
Soft mud moulding
Extrusion and wire-cutting-
Soft extrusion- Stiff extrusion
Of these, the soft extrusion and wire-cutting technique
is most widely used all over the developed world while
soft mud moulding is seldom practiced there. In India,
hand-moulding, which is the same as soft mud moulding,
is prevalent everywhere. Dry pressing, though considered
technically feasible, is not a commercially viable
technique for making ordinary fired clay bricks, and
hence not made use of in India.
Drying is done either under the sun (i.e. in the
open) or under a shed. The process may be hastened
by circulating hot kiln flue or steam through bricks
kept under the shed. This arrangement is called a
chamber dryer. Advanced countries now-a-days use a
chamber dryer or a tunnel dryer without exception.
For firing, open clamp, Bull's trench kilns, Hoffmann
kilns, vertical shaft kilns, tunnel kilns and roller
kilns are the available options, which are progressively
more and more fuel-efficient. Of these, open clamp
is the crudest form of brick-burning practiced anywhere
in the world. It is non-continuous (or batch) in nature,
while all other forms are continuous.
Using handcarts, dump trucks, conveyors, forklift
trolleys, setters, finger/transfer/kiln cars, etc
does material handling. All the said machinery/equipment/techniques
are either indigenously available or are being commercially
exploited in India in the manufacture of bricks or
other ceramic products.
5.2 First Step Towards Mechanization :
The present condition of the Indian brick industry
may be likened to the one that existed in England
during the period 1850 to 1900. Though all Indian
brick manufacturers are keen to mechanize their units,
no one wants to be the pioneer for fear of failure.
The experience of the industry with mechanization
has not been very encouraging so far and it has created
a kind of fear psychosis in the minds of brick field
owners. But if England and other advanced countries
could revolutionize their industries by sticking to
mechanization despite setbacks, why not India? India
can definitely achieve the same results by adopting
solutions of appropriate technology as a first step,
and then raising its level to match the state-of-the-art
by 2000 A.D.
Two most appropriate and techno-commercially proven
alternatives have been suggested here which, when
adopted immediately on a mass scale, will make entrepreneurs
come out of their mechanization phobia and set the
stage for rapid advancement.
a) Extrusion and Wire Cutting Machinery :
In this process, the requirement of raw-mix plasticity
is relatively high. Also, the process needs extensive
clay preparation. The prepared mix is first extruded
through a die of a pug mill into a continuous column
of clay, and then cut into individual bricks by taut
wires of a down-stream cutting machine. The inside
dimensions of the die form the length and width of
the raw brick while the distance between adjacent
wires determines its height. Both solid and perforated
bricks can be made using this arrangement. Some pug
mills are provided with vacuum pumps, which de-air
the raw-mix before extrusion resulting in a stiffer
consistency, sharp edges and reduction in dryer time.
Pug mills (with or without de-airing of 10,000 to
50,000 bricks per shift capacity are being manufactured
in India today.
Among all possible techniques, extrusion and wire
cutting technique lends the best finish to the product
and being truly continuous, it gives very high outputs.
It is well suited to automation and instrumentation.
Product diversity is another advantage of the technique.
By using different sets of dies, different sizes and
types of products like hollow blocks, pipes, split
tiles, grills, etc. can be made. The only limitation
of the technique is that the freshly extruded material,
being highly plastic, tends to crack due to pronounced
shrinkage if exposed to sun or wind immediately. Hence,
the green products have to be dried under an enclosed
shed and kept separate from each other in a single
layer. This calls for additional investment in sheds,
shelves and pallets ( or 'laths'). But with the use
of innovative designs and materials, and with proper
project planning this difficulty is easily surmountable.
b) Vertical Shaft Brick Kiln (VSBK) :
VSBK technology was developed in China and is a very
popular kiln in rural China for small-scale production
of bricks. It is estimated that around 60,000 VSBKs
are operating in China. Since 1990, the kiln has been
introduced in Pakistan, Nepal, India and in some countries
VSBK has a vertical shaft of rectangular or square
cross-section. The kiln works as a counter current
heat exchanger, with heat exchange taking place between
the air moving up (continuous flow) and bricks moving
down (intermittent movement). Green bricks are loaded
from the top in batches, the bricks move down the
shaft through pre-heating, firing and cooling zones
and are unloaded at the bottom. The combustion of
powdered coal (put along with bricks at the top) takes
place in the middle of the shaft. Air for combustion
enters the shaft from the bottom, gets preheated by
the hot fired bricks in the lower portion of the shaft
before reaching the combustion zone. Hot combustion
gases preheat the green bricks in the upper portion
of the shaft before exiting the kiln through the chimney.
Two fixed chimneys located diagonally opposite to
each other are provided to a shaft for the removal
of flue gases out of the kiln. A shaft lid is also
provided on the top of opening of the shaft. The lid
is kept closed during normal operation and hence flue
gases do not pollute the working area on the top of
the kiln. The provision of shaft lid, better ventilation
of the working area on the top and higher and bigger
chimneys are some of the improvements made in the
VSBK technology during its pilot testing in India
since 1996. The kiln has the potential to save 40
- 50 % fuel cost as compared to open clamp and is
best suited for production up to 15,000 - 20,000 bricks
c) Fixed Chimney Bull's Trench Kiln :
The Bull's Trench Kiln is popularly known as the
'Chimney Kiln' in India. It was patented by a scientist
named W. Bull in Germany in 1876 and its continuous
operation is based on the famous 'Hoffman Principle'.
The kiln is either oval, circular or rectangular in
shape and has a fixed chimney at its center. At least
a third of its total height is normally below ground
level and it can work on coal, lignite, wood or any
other lumpy organic waste as fuel. In the Punjab and
the Gangetic Plains, coal is used as fuel, while Gujarat
and Tamilnadu, lignite and wood are very common, respectively.
In the other parts of the country, the Bull's trench
kiln is little heard of.
As compared to an open clamp, the Bull's trench kiln
is at least 30 % more fuel efficient and restricts
the percentage of under / overburnt and broken bricks
to below 10 %. The chimney sucks in hot flue from
the burning zone and draws it through raw bricks and
cools down the fired product simultaneously. The top
of the brick setting is covered with ash, which acts
as an effective thermal insulation, leaving holes
for fuel feeding. All operations like brick setting
/ unloading, ash laying / removal, damper movement
and fuel feeding are performed manually. Brick field
owners with existing / proposed daily production of
more than 15,000 - 20,000 bricks should find this
alternative very attractive.
5.3 The Big Leap Forward :
The alternatives suggested in the preceding section
indicate only a few confidence building measures for
the fear-stricken and paralyzed brick field owners.
After this, they may go in for more efficient and
'state-of-the-art' kilns and clay preparation / material
handling equipment, in stages. Instead of extrusion
and wire-cutting machinery, manual or automatic semi-dry
brick presses could have been the next logical step
after hand-moulding. However, its indigenous development
is far from being satisfactory as yet, and it may
be some years before a techno-commercially proven
and dependable version is available in the market.
The first indigenously designed tunnel kiln for firing
perforated bricks, hollow clay blocks, etc. is being
commissioned at present in Kannur district of Kerala.
Its success will definitely encourage those straddling
the fence to follow suit immediately. Monnier type
tunnel kilns operating on coal or solid agricultural
wastes or the ones utilizing 'producer gas' generated
by gasification of agricultural wastes, represent
promising areas of the future.
Changing the seasonal nature of the brick industry
into a year-round one is an important consideration
for the progress of the industry. It will result in
better utilization of fixed assets and increased profitability.
It will provide yearly employment to workers and prevent
ups-and-downs in the prices by maintaining continuity
of supply. All this calls for covered drying and firing
operations. Use of chamber dryers utilizing hot flue
from the down-stream kiln may prove very cost-effective.
If required, the kiln flue may be supplemented with
hot gases generated by burning agricultural / industrial
wastes. Continuous dryers and kilns have very short
processing times, which result in reduced working
capital blockades and faster servicing of orders.
Earth, water, air and fire are the basic ingredients
of brickmaking. Hence as the Indian brick industry
progresses, it is bound to affect the environment
adversely. To minimize this impact, few useful recommendations
have been made here :
The recent Regulation passed by the Ministry of Environment
& Forests, New Delhi
( Extraordinary Gazette Part II - Section 3( i ) dated
2nd April 1996 ) has banned use of Moving Chimney
Bull's Trench Kilns all over India after 1st July
2001 and use of flyash as an ingredient of raw-mix
has been made compulsory for all brick manufacturers
falling within 50 km radius of thermal power plants.
The Regulation also prescribes emission standards
and chimney heights for various capacities of brick
plants and makes adoption of Fixed Chimney Kilns (
with / without settling chambers) and other improved
kilns mandatory. Maharashtra Government has also included
open clamps under the scope of the said Regulation.
Brickmaking is a high volume low margin business
in India and it is expected to remain so for many
years to come. The investment to turnover ratio for
viable mechanized brick plants working eight months
a year is around one at present. The prices of conventional
handmade clamp-fired bricks are increasing every year
by about 5 - 7 %. Machine-made and uniformly burnt
bricks definitely fetch a premium - and many times
advance payment - over the prices of conventional
bricks. This, coupled with the year-round working
of the mechanized units (incorporating chamber or
tunnel dryers and continuous kilns), will definitely
result in better scope for additional capital investment.
With globalisation and strengthening of the Indian
economy, constraints on imports are likely to ease
further in the coming years. This will create a good
scope for judicious application of imported machinery
and technology to plants of 50,000 to 1,00,000 bricks
per day. For smaller plants, however, indigenous machinery
and techniques are expected to retain their competitive
edge. The stiff extrusion and semi-dry pressing techniques
are other areas offering good scope for machinery
import / development.
Hence, the key to India's Clay Brick Industry becoming
world-class and seeing the light of the New Stone
Age lies in early adoption of cost-effective, appropriate,
sustainable and dependable machinery and technology,
whether indigenously developed or imported !