Generalized Bogue computations to forecast the mineralogical composition of sulfoaluminate cements based on fly ashes

Fly ashes, from an extensive database showing extremes in ratios of major oxides, are considered as potential raw meal ingredients for preparation of sulfoaluminate cements. Simple algorithmized, essentially Bogue-like, computations are performed in order to create a link between the chemical composition of raw meals and their mineralogical composition, as expected to result from their burning. The computations refer to a set of three-component raw meals, all containing limestone and gypsum but differing in the kind of fly ash introduced as the third raw meal component. The individual raw meal compositions are identified in computations, yielding three phase products, composed of C₂S, C₄A₃S; and C₄AF. The content of each phase is within the following limits: C₂S, 60·7–83·4 wt%; C₄AS, 4·2–27·2 wt%; and C₄AF 2·67–30·5 wt%. As a result, fly ashes are thus convenient raw sources for production of sulfoaluminate cements. Of special interest are fly ashes low in SiO₂/A₂O₃ or SiO₂/(Al₂O₃ + Fe₂O₃) ratios, providing clinkers with the preferred proportions of the mineral phases.