USE OE FLYASH AS AN ADDITIONAL 41ATERIAL IN CEMENT MORTARS

Abstract

Flyash is an industrial waste and at the sne time it is known to have pozzolanic properties and itc use as a new construction material has been in vogue in U.S.A•, U.S.S.R., Japan, France and other European countries since last more than 50 years. In India, Bokaro flyash was first time, used in the concrete work of Rl.hand Dam and sinco then it is being used for mass concrete of many doss as partial replacement of cement. It is also being used in mortars for lining of canals in Hiary'ana, Masonry dams in Rajasthan and many building works. It is also used in R.C.C. works. There i s a large potential for the use of flyash in cement mortars, concrete, manufacture of` flyash cement, light weight aggreft gate, cellular concrete, clay bound bricks etc. It has been found that when fly ash is used as a simple replacement of cement in mortars and concrete, its strength is reduced and it is only at the later ages of 90 day, and above that it attains the required strength. Fbr buildings and RCC vorkr4 it is required that mortars and concrete should attain required strength at 28 days . By using flyash in e c oss of that what it replaces cement, it acts as an additional material, gives more paste for reaction, reduces water requirements aid gives equal or more strengths at all ages. Fbr dams strengths are considered at 90 days and benefit of reduced heat of hydration is obtained only when it replaces the cement.