Optimization of the composition of fly ash cement by simulation

Abstract

In order to estimate the upper limit of fly ash as an additive to fly ash cement, the dependence of the hydration reaction of fly ash cement on two parameters, i.e., the fly ash particle size and C₃S quantity, were evaluated based on theoretical simulation. In the early stage of the hydration reaction, the reaction ratio was largely independent of the fly ash particle size; however, the reaction ratio became remarkably dependent on the fly ash particle size during the stage from three weeks to one year. Because controlling the fly ash particle size is inexpedient in industry, only the quantity of fly ash required for fly ash cement to achieve properties similar to those of ordinary Portland cement was simulated by regulating the quantity of C₃S. It was found based on the simulations that fly ash cement containing 20% fly ash in high alite cement containing 67% C₃S was adequate, and this result was confirmed by empirical evaluation.