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FACT SHEET
The use of fly ash, a waste product of thermal power plants, and other similar waste materials as construction material has been engaging the attention of the Government. In India, coal/lignite based thermal power plants account for more than 65% of electricity production at present. Pulverized fly ash is a residue resulting from combustion from ground or powdered or crushed coal/lignite. Fly ash is available in large quantities in the country as a waste product. This fly ash stored in dry condition in the ash ponds can become air born & thus polluting the air and resulting in health hazard.
The quantity of fly ash being generated is continuously increasing as the power generation is being augmented. The ash generation has increased from 40 million tons in 1993-94 to 100 million tons during 2002-03 and is expected to reach 175 million tons by 2012. According to research fly ash has proven suitability for variety of applications as admixture in cement/concrete/mortar, lime pozzolana mixture (bricks/blocks) etc. Fly ash as pozzolana reacts chemically with calcium hydroxide in the presence of moisture at ordinary temperature to form compounds possessing cementitious properties.
Following fly ash based innovative and commonly produced building products are available in India:-
Cellular Light Weight Concrete (CLC) blocks.
Fly Ash Based Polymer Composites as Wood substitute.
Fly ash based Portland Pozzolana Cement.
Ready mixed fly ash concrete.
Fly ash Sand Lime Gypsum (Cement) Bricks/Blocks.
Clay Fly Ash Bricks.
There are distinct advantages of use of fly ash based innovative building products: -
CLC blocks have better strength to weight ratio, reduces dead load resulting in saving of steel & cement and reduction of foundation size, better acoustics and thermal insulation & higher fire rating.
Addition of fly ash in Portland Pozzolana cement significantly improves the quality and durability characteristics of resulting concrete.
Fly Ash Sand –Lime Gypsum Bricks/Blocks require less mortar in construction, has controlled dimensions, edges, smooth and fine finish, energy efficient and cost effective.
Clay Fly Ash Bricks have better thermal insulation are cost effective and environment friendly.
Reduced heat of hydration.
Improved workability & Ease of pumping.
Superior microstructure leading to lower permeability.
Higher long term strength.
Better performance in aggressive environment.
Higher Electrical Resistivity leading to lesser chances of reinforcement corrosion.
Ministry of Environment and Forests has made use of fly ash bricks mandatory within 100 km radius of coal or lignite based thermal power plants. CPWD has already used 88 lakh fly ash bricks during 2003-04 in their construction projects and also encouraging more use of such bricks/blocks.
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