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Fly Ash Technology in India- A Report

Introduction and Background

India is the second fastest growing economy in the world today. The

construction industry is an integral part of the economy. Construction is

the second largest economic activity after agriculture. Clay fired bricks

form the backbone of this industry which is estimated to be at USD 70.8

billion1. It is poised for growth on account of industrialization,

urbanization and economic development. Therefore there is a rapid

increase in the demand of bricks in infrastructure and housing. There

are around 150000 brick kilns in India2. However the brick firing

technologies used in India are energy intensive and resource efficient. It

contributes to 22% of the total carbon-di-oxide emissions. It also results

in heavy particulate matter emissions. Top soil is also utilized for the

production of bricks. India needs around 60 billion bricks every year that

would exhaust around 180 million tonnes of top soil, making 7500

hectares of fertile land barren. In lieu of these shortcomings building

materials made of fly ash are gaining importance.

Fly ash refers to the ash produced during combustion of coal. It is

the fine powder formed from the mineral matter in coal, consisting of

the non-combustible matter in coal plus a small amount of carbon that

remains from incomplete combustion. It is captured by electrostatic

precipitators (ESP). Propertied of fly ash vary significantly with coal

composition and plant operating conditions. It can be referred to as

either cementitious or pozzolanic. Pulverized coal ash (PCA) is one of

major wastes generated during combustion of coal in thermal power

plants (TPP).

1 Overview of the Construction Industry in India- Report by The Indo-Italian Chamber of Commerce and

Industry.2 The Asuramunda Experience- A Report on Vertical Shaft Brick Kiln project implemented by Gram Vikas,

Orissa

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In 2010, TPPs accounted for 63% of the total installed capacity of

the country for electricity generation3. TPPs use low grade coal

producing a large amount of ash. In 2006-07, the fly ash generation

from power plants in the country increased to the level of 130 million

tonnes per year4. In 2008, approximately 150 million tonnes of

pulverized ash was generated. As the power requirements of the country

goes up, the amount of waste produced will also increase enormously

creating problems for its safe disposal due to lack of adequate disposal

facilities. Apart from land pollution, it is also a source of air pollution due

to release of PM, carbon monoxide, sulphur oxides. However, PCA can be

used as raw materials in other areas. It can be used in the construction

sector for roads, embankments, dams, dykes and building materials.

Brick sector has great potential in utilising fly ash. The Government of

India along with various R&D organizations has constantly been

researching the best possible means to utilize fly ash. The Fly Ash

Mission was initiated by the Department of Science and Technology

under Technology Information, Forecasting and Assessment Council

(TIFAC). This mission propagates various developments in the area of fly

ash utilization. MoEF, Ministry of Power, thermal power stations and R&D

institutions together have launched a Technology Project in Mission

Mode. Their focus is on the demonstration of coal ash related

technologies ensuring their large-scale adoption.

FLY ASH BRICKS

Bricks made from fly ash are gaining popularity continuously with the

development of proper technologies. Fal-G bricks are made of fly ash-

lime-gypsum or fly ash- cement-gypsum. The raw materials are blended

in desired proportions in a Pan mixer for 4-5 minutes and compressed.

3 Energy Statistics 2011( Eighteenth Issue)- Central Statistics Office, Ministry of Statistics and Program

Implementation4 R&D and Technology Development- Department of Science and Technology, Fly Ash Unit (FAU)

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They undergo curing for a minimum of 14 days and are then air dried for

7 days. Strength of these bricks can be engineered by varying the

compositions. The advantages of fly ash bricks include high strength,

low water absorption, uniform shape etc. Plants using this technology

are likely to be micro/small scale enterprises. Therefore, they dont

require any environmental clearance from MoEF. However, they do need

to obtain No Objection Certificate from the respective State Pollution

Control Boards. It has a payback period of around 2 years. Thus, it is

also attractive from a financial point of view.

Policy Scenario

In lieu of the problems arising due to the brick industry, the Government

of India issued a notification published in Gazette of India, Part II,

Section 3, sub section (ii) vide S.O. 763(E) dated 14 September 1999. It

placed restrictions on the excavation of top soil for manufacture of

bricks and promotes the utilization of fly ash for the same. According to

it, building materials used in construction shall be made partly or wholly

from fly ash instead of clay, top soil, limestone and other such materials.

Every construction agency within a radius of 100 km from a coal or

lignite based power plant have to utilise fly ash. It also directs TPPs to

supply fly ash free of cost to the manufacturers, construction sector and

the cement industry for atleast a period of 10 years.

Quality Specifications

Standards are already present for common burnt clay bricks. Bureau of

Indian Standards have also formulated specifications for clay fly ash

bricks.

IS: 12894: 1990 and IS: 13757:1993 provides specifications for fly ash

lime building bricks.

Various Methods of Utilization of Fly Ash

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Sakar Engineering

Successful Utilization of Fly Ash

There have been many instances in India where fly ash has been

successfully utilized in various projects. One of the most publicized

projects is the Bandra- Worli Sealink project. High volume fly ash

concrete incorporating 55% of fly ash was used. ACC has constructed

demonstration roads using high volume fly ash concrete with upto 50%

replacement at its Greater Noida and Faridabad ready-mix plants. It has

also constructed a small patch at Tikaria- Amethi. In Korba district of

Chattisgarh TPPs are utilizing the fly ash produced. There are 6 fly ash

brick manufacturing units present. Balco is utilising pond ash/ bottom

ash for construction/ widening of approximately 82 km long Urga- Hati

road. INSWAREB has been promoting the use of PCA technology for

bricks. In Vishakhapatnam scientists have constructed their own

buildings. After tsunami, Development Alternatives set up 2 brick

production centres using fly ash at Kilinjalmedu and Kottucherrymedu in

Tamil Nadu for large scale production of bricks for their post tsunami

reconstruction project. They are acquiring fly ash from Neyvelli Lignite

Corporation. There are several projects by the National Highways

Authority of India (NHAI) which are using fly ash like the Durgapur

Expressway, Haldia Port Connectivity project etc. It has also been used

at Nizamuddin bridge road embankment at Delhi for 1.7 km.

Radioactivity in Fly Ash

There have been concerns about the presence of radioactivity in fly ash.There have been very contradicting views on this issue. A research

paper published in the journal of Indian Academy of Sciences by a

doctoral student claimed that the fly ash from Kolaghat TPP has high

levels of radioactivity, enough to warrant remedial measures6. The

6 The Telegraph, Calcutta, India- March 28, 2005

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researcher urged to curtail the use of fly ash bricks. Another article

published by Scientific American states that coal ash carries into the

surrounding environment 100 times more radiation than nuclear plant

producing the same amount of energy. Radioactivity in fly ash is also

mentioned in the Techno Market Survey on Fly Ash bricks by TIFAC.

According to it, it is relevant while designing applications of fly ash

products. However, its mentioned that it is still in its nascent stage of

research. On the other hand, many scientists are of the opinion that

there is no need to panic. Their explanation is that coal contains

naturally occurring radioactive materials (NORM) and some of the

radioactivity is transferred to fly ash after the combustion of coal. A lot

of research has been done to note the radioactive elements present in

fly ash. According to U.S. Geological Survey, radioactivity of typical fly

ash is not significantly different from that of more conventional concrete

additives or other building materials such as granite or red brick. A study

was conducted in USA about the radiation hazards in coal fire plants

from 1975-1985. They experienced a 1-5% increase in natural

radioactivity in a 1 km area around the power plant7. Therefore, they

concluded that fly ash is not radioactive.

Promotion of Fly Ash in Orissa

Use of fly ash is gaining immense popularity and is being promoted by

various institutes like TARA, INSWAREB as well as the state governments

of Orissa and Andhra Pradesh. Fly ash based industries utilizing a

minimum of 25% by weight of fly ash as base raw materials were

included in the Priority Sector in the Orissa Industrial Policy 2001. With

Orissa emerging as the national hub for thermal power emphasis is laid

on making the industrialization process more sustainable in the Orissa

Industrial Policy 2007. Keeping this objective in mind, the Orissa

government is promoting investments in new cement plants based on

7 Radioactivity in Fly Ash?- Atif Mirza, Luke Snell, Ya Duinkherjev, Richard D. Stehley

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blast furnace slag and fly ash, which would be available in abundance

due to large number of steel and power plants coming up in the state.

Due to the persistent efforts of fly ash mission, the utilization of

fly ash increased from a mere 3% in 1994 to 27% in 2003-2004 to 46%

in 2006-2007. The present utilization has crossed the 50% mark.

However the unutilized fraction is also growing increasingly (70 million

tonnes in 2006-07). As a result, a lot still has to be done in this field to

reduce the unused fraction. It requires extensive awareness programs,

demonstrations and training workshops to shift towards these non-

conventional practices.

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