Large quantity of fly ash and blast furnace s lag are generated in India and many other developing countries every year. In absence of proper awareness and technology development, large portion of these by-products remain unutilized causing severe disposal and environmental problems.
The fly ash affects various properties of concrete in its green and hardened state, which are of significant importance to the durability of the concrete structures. The quality of fly ash varies not only from plant to plant, but it may vary within the same plant due to change in the source of coal or inconsistent boiler conditions. Therefore a continuous quality assurance programme is to be developed to avoid the use of low-grade inconsistent material. The use of good fly ash of a consistent quality with low carbon content, greater fineness and high pozzolanic activity can produce
economically a concrete of good quality and higher durability. The fly ash concrete may have slightly lower or comparable properties at early age but generally has better properties at later age when compared with controlled concrete. The use of fly ash in concrete or blended cement will have multifold benefits; conservation of limestone, reduction in green house gases, energy saving and environmental friendliness. The effect on various properties of concrete due to use of fly ash as an additional mineral admixture and requisite quality assurance systems on raw materials and production technology of blended cement are discussed in this paper.