Code No: TMS085 Price: 1440 Category: Foods & Agriculture: Sugar Industry By Products

Table Of Contents : Introduction- Fly ash: the problem, Size of the problem, What is fly ash, Current fly ash disposal practices and effects, Fly ash: a resource; Properties of Flyash- Relevance of properties of fly ash, Factors determing the properties of fly ash, Characteristics of fly ash, Physical characteristics, Factors to improve fly ash quality; Utilization of fly ash- Fly ash utilization, Fly ash application in agriculture, High value utilization of fly ash, Medium value utilizaion of fly ash, Low value utilization of fly ash; Fly ash in Building and Construction- Portland-pozzolana fly ash cement (pfc), Ready-mixed fly ash concrete, Lime-fly ash concrete, Fly ash-lime gypsum cement, Lean cement-fly ash concrete, Sintered fly ash lightweight aggregate, Fly ash-portland cement clinker, Lime-fly ash cellular concrete, Fly ash aggregate, Fly ash bricks and pre-cast blocks; Fly ash Bricks- Fly ash bricks: technology, grouping, Clay fly ash bricks, Fly ash red mud bricks, Sand fly ash bricks, Fly ash – lime bricks, Fly ash-lime-gypsum bricks, Other countries status, Lime fly ash cellular concrete blocks, Concrete building blocks with fly ash admisture, Constraints in the manufacture of fly ash bricks; Case studies, Economic details and Evaluation of technologies-Clay fly ash bricks, Sand fly ash lime bricks, Fly ash lime bricks, Fly ash lime gypsum bricks, Utilization of fly ash in various works in neyveli, Economics of manufacturing lime: fly ash cellular concrete blocks using CBRI process, Some recent initiatives undertaken by government departments for promoting fly ash utilization; Radiation effects of fly ash in construction- Coal, fly ash and radioactivity, Findings in India, Conclusions; Conclusions and recommendations & action plan - Conclusions , Recommendations & action plan, Impact; Glossary; References; Keywords

Scope and Objective of the Study

The study covers the following aspects, which are based on the following Terms of Reference:

• The relationship of fly ash bricks to construction sector, in the context of fly ash generation by coal based thermal power plants.

• The present status of fly ash brick manufacture in India, availability of fly ash, and potential of utilization of fly ash bricks.

• Status of fly ash brick technologies in India by way of research work being done by various institutions, and technologies being used for manufacture of these bricks.

• Keeping in view, the technological status for fly ash brick manufacture, assessment of the technologies for its relevance and suitability, keeping in view material inputs required, energy requirements, costs, infrastructure requirements etc.

• Evaluation of the short-term and long-term economic aspects based on the above. This analysis is relevant for technology evaluation and assessment.

• Spin-off in terms of those in the construction sector and environment.

• Based on the technology assessment, impact and spin-offs, identification of inputs to effect the implementation of recommended course of action.

• A detailed Action Plan for implementing the recommended options for India, giving the available technologies. Identification of a set of agencies identified for implementing the same.

• Examination of impact of the recommendations.

• Approach This Techno-Market Survey looks into technologies suitable to India based on aspects like requirements of inputs, costs, economic benefits and impact etc., and is an overview report for technology options available for fly ash brick manufacture. For the purpose of construction industry, fly ash bricks and precast blocks (solid and hollow) are direct substitutes of conventional bricks. Thus, this study looks at the technologies of both.

It may also be noted that various cements and mixes which can be made using fly ash, have the potential become raw materials for fly ash bricks and blocks of various specifications. Therefore, this aspect has also been discussed.

In some fly ashes and its products, radio activity has been noticed due to the presence of trace elements. This is relevant while designing applications of fly ash products. Though this aspect is at a nascent stage of research, it has been thought relevant to be discussed.

India will continue to depend heavily upon its coal reserves for power generation. Based on the thermal power generating capacity as per different Five year Plans, starting at about 51 million tonne in 1994, India will generate about 90 million tonne of fly ash by the turn of the century.

By virtue of its physical characteristics and sheer volumes generated, fly ash is a serious problem. Some of the aspects of the problem are:

• It is a very difficult material to handle in dry state because it is very fine and readily airborne even in mild wind. 

• It disturbs the ecology of the region, being a source of soil air and water pollution.

• Long inhalation of fly ash causes silicosis, fibrosis of lungs, bronchitis, pneumonitis etc.

• Flying fine particles of ash create great nuisance for people living near power stations, corrode structural surfaces, and affect horticulture.

• Eventual settlement of fly ash particles over many hectares of land in the vicinity of power station brings about perceptible degeneration in soil characteristics.

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Current Fly Ash Disposal Practices and Effects

At thermal power plants, fly ash is currently collected / disposed off by using wet or dry systems. In cases, where fly ash collection systems are not very efficient, a portion of it escapes into the atmosphere causing environmental pollution.

Although accurate data about the influence of the polluted atmosphere on the state of health of persons inhabiting the vicinity of the power station is not available, cases of pulmonary diseases, including asthma and silicosis are found to be on the increase. In association with moisture in the atmosphere, fine particles of fly ash often form aerosols which affect visibility around power stations, though to varying extent. Aerosols, being particles in colloidal dispersion and of lower bulk density, take a long time to settle down as fine precipitation of dust. These can thus be carried over considerable distances from the power station.

In the wet system, fly ash is mixed with water and sluiced to settling ponds or dumping areas near the plant. Being cheaper than any other manner of fly ash removal, it is the widely used method at present in India.

Electrostatic precipitation is the most popular and widely used method of emission control today which enables collection of dry fly ash. The characteristics of coal contributes significantly to the characteristics of fly ash collection. After arresting the fly ash in ESP, it is then transported to silos through suction or by pressurized air. When required, this can be obtained in the container for further transportation directly from the silos through chutes at the bottom, or to the delivery point by pipeline using vacuum suction or pressurized air.

Fly Ash - A Resource

Utilization of fly ash can result not only in reducing the magnitude of the environmental problems, but it is also to exploit fly ash as raw material for value added products (and conserve traditional materials), and for extraction of valuable materials.

Amongst many uses that fly ash can be put to, that in building materials is particularly suitable. It is also anticipated, that there would be considerable short-fall in production of various building materials. According to a study, there would be a large short-fall in the production of bricks – to the tune of 25 billion bricks on an estimated demand of 100 billion bricks per year in India by the turn of the century.

Considerable work ahs been done in various research institutions in India for utilization of fly ash. In spite of the recognition of the size of fly ash utilization / disposal problem and availability of technologies appropriate for Indian fly ashes and applications, India utilizes hardly about 3% of the total fly ash generated.

Considering the colossal problem of disposal of fly ash, as well as the opportunities for conserving traditional resources like clay, cement, etc., the manufacturing of fly ash bricks is very important from the nation’s environmental and economic points of view.

Government Initiatives

Apart from the technological research and development effected by TPPs, academic and R&D institutions, various departments and ministries of the Government of india have taken initiatives in the area of fly ash utilization. Since the area of fly ash utilization involves many disciplines like power, industry, urban development, environment, science and technology, often, these initiatives are by inter-ministerial groups or multi-disciplinary bodies. Some of the main initiatives are discussed below:

• The National Housing Policy (1998) by the Ministry of Urban Development, and subsequent draft policy documents lay stress on promotion of low cost building materials which include fly ash. Building Materials and Technology promotion Council (BMTPC) in 1990, under the aegis of Ministry of Urban Development, as an inter-ministerial apex organization, ahs been involved in coordinating with various PWD schedules, preparation of technology profiles for various fly ash based products, providing inputs of towards technology scanning, fixing of land rent, policy review etc.

• A centrally sponsored scheme National Network of Building Centers was launched in 1988-89 through HUDCO.

• Fiscal measures announced by the Ministry of Finance in its past three annual budgets include exemption/reduction of excise duty on the production of low cost building materials/components; reduction in custom duty on the import of equipment, machinery and capital goods required for the production of building materials such as fly ash bricks; light weight aggregates, light weigh concrete elements etc.

• HUDCO and NHB are extending financial support to promote industrial units for production of building materials based on fly ash.

• The Ministry of Power (MoP) has proposed a legislative measure to curb utilization of top soil for making bricks within a suitable distance like 50 km from the TPPs, and providing fly ash free of charge. Efforts are on in coordination with MoP to increase the utilization of fly ash to the extent of 50% of the production by 2000 AD from the present about 2-3%.

• An inter-ministerial council – National Waste Management Council (MWMC) has been setup under the Ministry of Environment and Forests (MoEF) to utilize industrial wastes.

• A Fly Ash Mission has been constituted with DST (TIFAC0 as the nodal agency and in coordination with MoEF, MoP.

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Methodology

The following steps were taken for effecting the study:

Data Collection

Secondary Data Collection
 

• Extensive literature search was undertaken for secondary data collection. This included the details of work done and literature with research and technical institutions, journals and technical papers, published reports of the government and semi-government bodies, voluntary agencies, international bodies, five year plans and perspective plans, expert committee and working group reports of relevance, technical literature.

Primary Data Collection
 

• The desk research was further supplemented by mail survey through structured questionnaires and personal interviews for better insight into various facets of fly ash brick manufacturing technologies. Interviews and personal visits were being undertaken to supplement the questionnaires.

The sources of information were classified into:

• Fly Ash generators i.e. electricity boards/thermal power stations.

• Potential users i.e. brick manufactures, housing boards, building materials, building contractors, individual house owners, archetects etc.

• R&D institutions.

• Plant and equipment suppliers.

• Monitoring / facilitating agencies.

Separate questionnaires were designed for first four of the data sources mentioned above. A detailed letter was written in the case of facilitating agencies. First follow up was done after providing 3-4 weeks for the responses to reach us. A second follow-up was carried out in cases where either the response was till awaited, or where more details or information was necessary. Finally about 30% respondents responded to our questionnaires after active follow up.

Annexes II to VI give the lists of the agencies in the above five categories who were contacted for the purpose of data collection.

The next step was compilation and analysis of data. The existi9ng data, specifications and parameters of technologies and processes, reports and survey results along with projections made by various planning bodies formed the basis of our analysis of technologies, apart from personal interviews, and in-house study and database.

The assessment of technologies considered the following aspects:

• Status of technology

• Capital equipment and cost requirements

• Volume of production / adaptability to various levels of operations

Limitations of the Study

The following may be kept in view while studying the report:

• Confusion prevailed among the agencies contacted, regarding the basic technologies for the manufacture of fly ash bricks on one hand, and optimizing certain parameters of the basic technologies with respect to local situation of fly ash quality, cost and level of operation for making the technology commercially relevant, on the other. Thus, considerable effort had to be made to clarify these aspects to the institutions to enable getting a more accurate technological status. The feedback from the institutions in many cases continued to be confused on this account.

• Good amount of data and research material could be obtained from Indian institutions. However, information on foreign technologies has been limited.

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Organization of Report

The main body of the report is preceded by detailed contents including lists of figures, tables, and annexes followed by units used in the report. This is followed by executive summary giving briefly the scope and objectives of the study, importance of the topic, methodology, limitations, major observations / findings, and recommendations & action plan.

Chapter 1 explains the importance of the topic, scope, methodology of data collection and analysis.
Chapter 2 discusses the properties of fly ash. An overview of the utilization potential of fly ash is presented in
Chapter 3. In chapter 4, the utilization potential of fly ash in construction sector, of which fly ash bricks is a sub-set, is the focus.
Chapter 5 discusses the fly ash brick technologies and
Chapter 6 the specific case studies / projects related to manufacture of fly ash bricks. In some quarters, concerns are being expressed regarding possible radioactive effects of fly ash. Studies are underway in India and some other countries. This aspect is considered in
Chapter 7. Chapter 8 gives the conclusions, recommendations & action plan.

All chapters are preceded by a brief synopsis of the chapter, and key words. The main report is followed by glossary, giving the acronyms and abbreviations used in the report, a listing of all the key words corresponding to various chapters. References which have been used for certain inputs are listed after the key words. Wherever these references have been quoted / data or technical specifications taken in the text, these have been cross-referred by their serial number (appearing as superscripts in the report) in the list of References.

Conclusions

• The total fly ash generation at TPPs by the turn of the century is estimated at about 90 million tonne.

• Utilization of fly ash while reducing the environmental problems is a resource for value added products.
• Utilization of fly ash in building materials is of special importance. Considerable short-fall in production of various building materials is anticipated in the near future. The short-fall in the annual production of bricks is expected to be of the order of 25 billion bricks by the turn of the century.

• The control and information of variability of fly ash properties especially the fineness, carbon content and other chemicals / minerals are necessary for facilitating more specified uses of fly ash.

• The correlation of the pozzolanic properties of fly ash with its constituents has been established. However, this has not enabled to standardize product or process designs.

• The technologies for the manufacture of fly ash bricks can be classified into the following main technology routes:

• Clay – fly ash bricks

• Red mud – fly ash bricks

• Sand-fly ash bricks

• Fly ash – lime bricks

• Fly ash – lime/gypsum bricks

Advantages of clay-fly ash bricks are:

• Fuel saving in the range of 15%-35% (coal consumption) or coal saving upto 3-7 tonne per lakh bricks.

• Drying losses are checked in case of plastic black and red soils. Excessive linear drying shrinkage is reduced.

• Higher strength.

• 30-40 tonne of fly ash per lakh bricks can be utilized in case of alluvial soils, and 100-125 tonne per lakh bricks in case of red and black soils.

• Clay, a valuable and irreplaceable economic resource, is conserved to the extent of 40% by weight.

• ricks conforming to IS:3102-1976 can be manufactured.

• Uniformly in shape and size.

• Comparatively less quantity of cement mortar by 20%-25% is required.

• Water absorption is 13% to 15% as compared to 20% for conventional bricks.

• Outside wall plastering could be avoided as these bricks are smooth.

• Fly ash lime bricks are more resistant to salinity and water seepage.

• Lower bulk density of fly ash bricks help in minimizing the resultant load on load-bearing walls.

Selection of fly ash brick manufacturing technology should be based on the availability of raw materials, financial strength of the entrepreneur, and the market characteristics (size and nature of applications required for the strength of the bricks / blocks etc.). Clay fly ash brick manufacturing is most suitable for transition with minimum changes from existing practices and manual moulding of bricks which is most common. Red-mud should be used share this industrial waste is available. CBRI technology is welltried and tested. These can also have semi-mechanized operations, but manual operations are most effective cost. Sand-fly ash bricks, which need chemical accelerator, are conductive to manual or semi-mechanized operations. Technologies are available from CBRI, CFRI, AEC, SAIL, NCBM. Fly ash –lime bricks are superior and are more cost effective for semi-mechanized / mechanized operations. NCB, ACC and CBRI technologies are available. Fly ash-lime-gypsum bricks / blocks are very good products giving the highest strength among various bricks. These require relatively higher investment and expensive raw materials to give a range of high strength products. This is most suitable for mechanized operation, though semi-mechanized operations are also possible. AEC, ITC-B, NLC, INSWAREB, Bhanu International have developed technologies which are in operation.

• Due to transportation cost, the use of fly ash beyond 40-50 km from the TPP becomes uneconomical. Also, appropriate technologies for fly ash handling and transportation are not available.

• Fly ash of consistent quality and of desired grade is often not available on a long term basis. The difficulty in obtaining the fly ash in dry state from TPPs adds to the problems.

• Absence of technology transfer efforts and extension services/technological back-up support have rendered fly ash brick technologies unusable.

• Brick moulders and manufacturers do not readily agree to diversify from the conventional practices without incentives to cover the risks.

• The indigenous availability of good quality machines like brick press, mould equipment, cutting machines, sintering strand or kiln along with spare parts which are required for large commercial scale production of fly ash based building materials is till not guaranteed. The cost of importing these machineries is very high, which often makes the project economically not viable.

• When coal is brunt, most of its mineral mater is fused into ash, and majority of its radioactive substances get concentrated in ash. Fly ash applications could lead to irradiating those who may be residing in closed buildings, with fly ash products. This aspect needs a further study. Otherwise, it is quite safe to use fly ash in building construction.                                                                                                                                                                             Back                          

Recommendations & Action Plan

The fly ash generators in India have not yet adequately recognized that bottom ash and fly ash as two distinctly different resource materials.
Once this is realized, bottom ash and fly ashes collected from different locations would not be indiscriminately mixed together but would be suitably collected in a manner as not to destroy their special features.
Dry collection systems may be designed and implemented for identified storage in silos.
The wet disposal systems should be discourage, also on account of the threat to underground water resources through percolation of soluble cations of alkali metals and those containing traces of arsenic, fluorine, molybdenum, selenium, mercury etc.
For similar reasons, fly ash should not be discharged into rivers or lakes.
For generators, environmental clearances should be granted only to projects which integrate highest standards of collection and storage of fly ash.
Rigid guidelines be issued to existing projects to adhere to stringent regime for emission control and collection and storage of dry fly ash within a specific time frame. Suitable penal clauses should be imposed and be implemented effectively in case of non-compliance.
Agencies :

• Ministry of Environment

• Ministry of Power

• Project appraising authorities, financial institutions

• NTPC

• CEA

• SEBs

Quality of available fly ash can be improved by taking suitable measures.
This is important to improve the value-added potential of fly ash, and its acceptability by the manufacturing sector, for making high quality bricks and blocks using fly ash.
This has considerable overlap with the above recommendation.
Greater pulverizing of coal and using 20-25% higher air in combustion, apart from better collection, transportation and storage practices can result in improved fly ash quality.
However, these factors may affect boiler operation. The whole process needs to be optimized, and standardized guidelines issued to that effect.
Agencies :

• Ministry of Environment

• Ministry of Power

• Project appraising authorities, financial institutions

• NTPC

• CEA

• SEBs.

While technologies and processes are being developed in a number of privae and governmental institutions in India, the potential of using fly ash and the technologies seem to have by-passed the average entrepreneur for manufacture of fly ash bricks and blocks, and also the potential users of these building components.

There is an urgent need for dissemination of information about these products and technologies, and educating the entrepreneurs and users. Extensive applications will also help to improve the technologies and make them more commercially relevant. A few large scale demonstration projects using fly ash components need to be effected across the country. A concerted effort needs to be made in this direction to obtain funding from industry / SEBs. Making technologies commercial will also generate funds for further research and development.

The process of selection, extension and promotion of proven fly ash building components and technologies conforming to Indian Standards and Building Codes needs to be strengthened to help the user / entrepreneur.
BMTPC currently gives extension and education for a variety of building materials. It needs to focus more sharply on fly ash components along with central and state government departments.

Further, it could help in giving guidance on financial and other assistance to entrepreneurs for the manufacture and marketing of appropriate and innovative materials.

Agencies :

• Ministry of Power

• BMTPC

• NTPC

• SEBs

• Research institutions like CBRI, CFRI and NRDC, various CSIR labs, etc.

• HUDCO, NBO, private builders, architects and town planners

• Academic institutions like IITs, engineering colleges, schools of architecture etc.

• Ministry of Urban Development

• State Governments / PWDs / Housing Boards.                                                                                     Back

selection of fly ash brick manufacturing technology should be based on the availability of raw materials, financial strength of the entrepreneur, and the market characteristics (size and nature of applications, i.e. required strength and quality of the bricks / blocks etc.).

• Clay fly ash brick technologies should be encouraged for conversion of large number of clay fired brick units and urgent steps taken is low investment and minimum changes from status quo are required.

• Sand fly ash bricks should be introduced as a second step to conversion from clay fired bricks, or where semi-mechanized operations are justified on the basis of market demand.

• Fly ash-lime bricks should be introduced where markets are larger to justify semi-mechanized or mechanized operations, and the entrepreneur has access to larger funds and raw materials.

• Fly ash –lime gypsum bricks/blocks are very good products and should focus on large high quality markets where higher investment and product cost can be accepted by the market which would ultimately find the product cost-effective.

State agencies and other public construction agencies should draw up plans for the use of fly ash bricks and related technologies to the extent of at least 10% of total annual construction. Towards this, incorporation of the use of fly ash building components in the national standards and specifications and their schedules needs to be taken up urgently. Agencies 

• BMTPC

• Research institutions like CBRI, CFRI, NRDC, various CSIR labs, etc.

• HUDCO, NBO, private builders, architects and town planners

• Academic institutions like IITs, engineering colleges, schools of architecture etc.

• Ministry of Urban Development

• State Government / PWDs / Housing Boards

Certain plant and equipment is required to be imported for availing large scale production of fly ash based products like light weight sintered aggregates and autoclaved blocks. Several European countries like Sweden, France Germany etc. have proven technologies for mechanical plants and material handling systems. The know-how and expertise in processing fly ash for mass consumption, ceramic burning technology, mechanized cutting and drying, and adequate R&D infrastructure are prerequisites for superior quality fly ash product and process development. The import of machinery for automatic cutting and hydraulic pressing and necessary know-how may be allowed on easy terms, wherever necessary, for early commencement of high quality fly ash brick manufacture.
Agencies :

• BMTPC

• Ministry of Power

• Ministry of Finance

• Ministry of Commerce

• Ministry of Urban Development

• Associations of industries like CII, FICCI and ASSOCHEM.

Transportation of fly ash is problematic. Fly ash should be utilized close its source. While this would increase the cost of transportation of bricks, a part of the saving in cost of fly ash disposal should be used to subsidize this cost (disposal of fly ash in any unproductive use should be made penal and expensive).

Transportation of fly ash should be done in bulk by railway tankers or road tankers, suitably fabricated and equipped. Automatic loading and unloading through compressor / vacuum pumps mounted on the tankers should be utilized.

• NTPC

• SEBs

• Ministry of Surface Transport

• Ministry of Railways

• Associations of Automobile Manufactures

• Manufacturers of commercial vehicles and material handling equipment.

Variations in fly ash quality creates special problems for manufacturers of fly ash products. The small entrepreneur may not be in a position to afford adequate testing facilities. There is a need to have technical support in this direction. Each batch of fly ash could also be classified and certified at source to enable the manufacturer to know what he is getting.

Suitable agency should be set up to supply dry fly ash of certified quality conforming to IS:3812-1981.
Agencies :

• CEA

• NTPC

• SEBs

• BMTPC

• Research institutions like CBRI, CRRI, NRDC, various CSIR labs, etc.

• HUDCO, NBO, private builders, architects and

• Ministry of Urban Development. Industry Associations

• Bureau of Indian Standards

While it is generally known that lime reactivity of fly ash increases with fineness, no definitive relationship has yet been evolved in this direction. Special research project needs to be taken to evaluate relationship between lime reactivity of fly ash and its physical and chemical properties. This could prove a boon for fine tuning the bricks/block making processes to suit the variations in the fly ash properties as made available by the TPPs. This needs to be done by a set of research institutions along with fly ash generators and potential entrepreneurs.
Agencies :

• NTPC

• BMTPC

• SEBs

• Research institutions like CBRI, CRRI, NRDC, various CSIR labs, etc.

• HUDCO, NBO, private builders, architects and

• Academic institutions like IIT,s engineering colleges, schools of architecture etc.

Application of fly ash as building component is slowly gaining acceptance. This can increase the use of precast fly ash bricks/blocks. Nonetheless, full scale structural engineering and cement chemistry studies are forwarded. An independent code of practice and testing needs to be developed for effecting large scale utilization of fly ash.
Agencies :

• NTPC

• SEBs

• BMTPC

• Research institutions like CBRI, CFRI, NRDC, various CSIR labs, etc.

• Academic institutions like IITs, engineering colleges, schools of architecture etc.

Agencies :

• BMTPC

• CEA

• NTPC

• SEBs

• Research institutions like CBRI, CFRI, NRDC, various CSIR labs, etc.

• BUDCO, NBO, private builders, architects and town planners

• Academic institutions like IITs, engineering colleges, schools of architecture etc.

• Ministry of Urban Development

• State Governments/PWDs/Housing Boards

• Financial institutions

• Ministry of Environment

Agencies :

• BMTPC

• CEA

• NTPC

• SEBs

• Research institutions like CBRI, CFRI, NRDC, various CSIR labs, etc.

• HUDCO, NBO, private builders, architects and town planners

• Academic institutions like IITs, engineering colleges, schools of architecture etc.

• Ministry of Urban Development

• State governments / PWDs / housing boards

• NGOs and voluntary agencies

• Bureau of Indian Standards.

• Possible effects of radio activity needs to be studied for long term impact. The findings should be integrated into the overall policy framework. Guidelines should be issued regarding design and ventilation aspects for utilizing fly ash based building materials and components.

• BMTPC

• BARC

• Research institutions like CBRI, CRRI, NRDC, various CSIR labs, etc.

• Ministry of Urban Development

• Bureau of Indian Standards.

    Impact

• Disposal of 51 million tonne of fly ash per year today is a major problem. The country is productively using only about 3% or 1.5 million tonne of fly ash. Thus, 49-50 million tonne of fly ash per year at present poses environmental threat. This figure will grow to over 87 million tonne per year by the turn of the century, if present dismal level of utilization only ash is maintained.

• The demand for bricks is expected to be about 100 billion per year by the turn of the century. Even if only 50% of the estimated demand of 100 billion bricks per year, is met from fly ash for productive use saving alternate resources, and reducing environmental hazard to that extent. In addition, it would save thousands of hectares of land from being used as ponding area. And this still does not account for the potential of using other industrial wastes like red-mud.

• As stated earlier, the demand for bricks is expected to be about 100 billion per year by the turn of the century. Even if only 50% of the estimated demand of 100 billion bricks per year, is met from fly ash by the turn of the century, about 1 lakh ha of land would have been saved from turning into waste land per year.

• Translating the above two into financial cost can be mind boggling. Add to it, the direct saving in energy cost which can be effected by adopting certain processed for manufacture of fly ash bricks / blocks.

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