Volume 28, Issue 6 (November 2000)
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 optimum lime content of fly ashes. Strength obtained at different ages becomes 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 different fly ashes with various lime contents after curing for different periods, it has been established that the effect of the curing period becomes important for optimum lime content of certain fly ashes depending upon their chemical composition. The optimum lime content corresponds to the production of a maximum amount of calcium silicate hydrate compounds of Type I. In addition 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 fly ashes. Both methods compared well and hence the simpler free swell sediment volume test may be adopted.