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 world over.

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 material.

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 very existence.

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 fresh assignment(s).

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 Workers :

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 :

Asence of competent and dedicated people who can develop 'appropriate' and 'sustainable' technologies based on these principles and prove their commercial value under varying socio-economic conditions, is the main cause of concern to the industry.

5.0 APPROPRIATE TECHNOLOGY - REMEDY TO ALL ILLS :

From the foregoing discussion, it does not take more than common sense to suggest that the answer to the Indian Clay Brick Industry's present problems lies in adoption of 'commercially successful' mechanization. This calls for development and application of appropriate technology (also called intermediate technology) characterized by its cheapness, smallness of scale and simplicity.

The technology should fulfill the following criteria :

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

Technique	Typical water content in raw-mix [%]
Soft mud moulding	25-35
Extrusion and wire-cutting- Soft extrusion- Stiff extrusion	20-2515-20
Semi-Dry Pressing	5-15
Dry Pressing	< 5

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 of Africa.

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 per day.

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 !