The Hindu : National : Fly ash technology and construction of eco-friendly houses

Online edition of India's National Newspaper
Tuesday, Dec 26, 2006
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Fly ash technology and construction of eco-friendly houses

Fly ash technology is providing relief to the overstressed resource base of soils being mined for the production of fired-bricks. This is demonstrated in the post-tsunami reconstruction project in South India. The massive task of reconstruction after the tsunami has necessitated the requirement of large amounts of high quality building materials in a short period of time; material that would also resist the deteriorating effects of the salt water in coastal areas. Fired bricks, the popular materials for construction, have already stressed the scarce resource of available soil.

Fly ash, available in plenty as a waste from the Neyveli Lignite Power Corporation's Thermal Power Plant in Tamil Nadu, India, has shown a way. The SOS Children's Villages of India, Chatnath Homes in their initiative to reconstruct houses in village Puthukuppam, Nagapattinam district have used this industrial waste to produce high quality walling material and construct eco-friendly and cost-effective houses. The technology has been sourced from Development Alternatives Group, a Non-Government Organisation, with its head quarters in New Delhi.

Fly ash, a by-product of the thermal power plants has long been rued as an industrial pollutant occupying large tracts of land in rural and semi-urban areas. It flied in the slightest air and is easily inhaled. Its inhalation has been linked to silicosis and results in TB, asthama and weakening of the lungs. The massive generation of this ash by thermal power plants has become a major cause of concern for people living in cities and towns in the country.

The use of fly ash in building bricks, first popularised in India by the Institute for Solid Waste Research and Ecological Balance (INSWAREB) in Vishakhapatnam, India, is now rapidly gaining acceptance in construction works. The World Bank has now entered into an agreement with INSWAREB to promote this environment friendly technology - a move that would also yield revenue through sale of carbon credits.

At Puthukuppam, the fly ash blocks are produced locally providing economic benefits to the tsunami affected villagers. Other post-tsunami response projects in South India in Nagapattinam and Puducherry are promoting this technology.

In the manufacturing process of blocks, fly ash has been used as primary filler and sand is added as secondary filler with waste gypsum, lime and small amounts of cement to make fly ash blocks. These blocks permit various construction applications as they are of the same size as commonly available fired bricks.

Blending fly ash with concrete can produce a more durable structure, resistant to corrosion as well as water. The blocks are made using compression technology, so there is no release of harmful materials into the atmosphere. As the blocks are of similar size as traditional bricks, these can be used in normal masonry. The strengths of blocks being used in the coastal areas have been found to be higher than locally available country bricks. The blocks also indicate better water absorption characteristics and therefore can be used for exposed masonry constructions.

Fly ash as an additive to cements, concrete works and road works is not being popularised by the Government as well as private sector initiatives.

The Department of Science and Technology of the Government of India through its fly ash mission is promoting the use of this material in various applications.

In summary, the erstwhile waste of the power plants has become a manna for the building industry struggling to seek environment friendly, high quality and affordable alternatives. The use of fly ash bock technology has shown a way to reduce the consumption of energy and the use of scarce agricultural soil required for the production of traditional fired bricks and at the same time provides a solution to the environmental hazard of dumping ash as has been the practice of most power plants in India.

Zeenat Niazi

Program Director,
Rural Habitat Program Development Alternatives,
New Delhi.

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