Fly Ash

Fly ash is a fine powder that is a byproduct of burning pulverized coal in electric generation power plants.
Fly ash is a pozzolan, a substance containing aluminous and siliceous material that forms cement in the presence of water. When mixed with lime and water, fly ash forms a compound similar to Portland cement.

Fly ash can be used as prime material in many cement-based products, such as poured concrete, concrete block, and brick.
One of the most common uses of fly ash is in Portland cement concrete pavement or PCC pavement.
Road construction projects using PCC can use a great deal of concrete, and substituting fly ash provides significant economic benefits. Fly ash has also been used as embankment and mine fill

The National Thermal Power Corporation has developed geo-polymer aggregate from fly ash as a replacement to natural aggregates for use in building construction.

Part of the concept of waste-to-best to make best use of fly ash generated in the thermal power plant.
Geo-polymer aggregate will not only increase fly ash utilisation but also saves the environment. Further, the requirement of land for ash ponds will be negligible. Geopolymers are inorganic, typically ceramic, materials that form long-range, covalently bonded, non-crystalline (amorphous) networks.
In fact, fly ash based geo-polymer mortar will act as a binding agent. The geo-polymer aggregates will help in reducing carbon emission and has great potential for reduction of water consumption.
According to one estimate, the requirement of aggregates for infrastructure development in the country is about 2,000 million tonnes every year.
The aggregate developed by NTPC from fly ash will help in meeting the demand to a great extent and will also reduce the impact on the environment caused by natural aggregates which require quarrying of natural stone.

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