Optimum lime content for fly ashes and the role of the curing period

The determination of the optimum lime content of fly ash is very important to enhance its use. Recently, methods have been established to obtain the o ptimum lime content of fly ashes. Strength obtained at different ages becom es important for different applications. The effect of the curing period on the optimum lime content of fly ashes is not established, nor are methods available for obtaining the same. Based on detailed strength tests on diffe rent fly ashes with various lime contents after curing for different period s, it has been established that the effect of the curing period becomes imp ortant for optimum lime content of certain fly ashes depending upon their c hemical composition. The optimum lime content corresponds to the production of a maximum amount of calcium silicate hydrate compounds of Type I. In ad dition to the strength test, the sediment volume test has also been used to study the effect of the curing period on the optimum lime content of the f ly ashes. Both methods compared well and hence the simpler free swell sedim ent volume test may be adopted.