Where is the iron? Clinker microanalysis with XRD Rietveld, optical microscopy/point counting, Bogue and SEM-EDS techniques

This paper presents the use of different techniques to assess the amounts of the main mineralogical phases in Portland cement clinker. The amounts measured by quantitative XRD analysis (Rietveld) show differences when compared to the Bogue calculation and this is particularly notable for the ferrite phase within certain clinkers. The amount of elemental substitution within the major clinker phases was determined by SEM-EDS microanalyses and the results show that defined amounts of iron oxide can be incorporated within the alite, belite and aluminate phases. Therefore even if a significant amount of the ferrite phase is expected due to the Bogue calculation, it is quite possible that less or no ferrite will be formed during clinker production.