Pozzolana from Fly Ash

When pulverized coal is burnt in kiln the ash is carried forward in the gases as fused (soften) particles which solidify into a roughly spherical shape. It is called as fly ash or pulverized fuel ash. The properties of this material as a pozzolana was first reported on in 1937 and its use in concrete started to develop in the USA in the following decade particularly for mass concrete dams. Later its use became wider and spread out to many other countries. In India fly ash, an industrial by-product from thermal power plants, with annual generation of approximately 108 million tones and its proven suitability for variety of applications as admixture in cement/concrete/mortar, lime pozzolana mixture (bricks/ blocks) etc. is claimed as an ideal material which attracts the special attention. Cement and concrete industries account for 50% fly ash utilization at present. Up to 35% of suitable fly ash can directly be substituted for cement blending material. Addition of fly ash significantly improves the quality and durability characteristics of resulting concrete. Use of blended cement has now become very popular world over from durability and environmental benefits point of view.