Mineralogical composition of fondu revisited

Standard grade calcium aluminate cements manufactured from natural raw materials by fusion have complex phase compositions. This is due to the presence of elements other than Ca and Al in the clinker. The main impurities are Fe2O3 and SiO2. MgO and TiO2 can also be found, depending on the raw materials used. Fe2+ is also present, as a result of a reducing atmosphere in the kiln. Recent applications of techniques such as x-ray quantification by the Rietveld method and TEM observations of the clinker have provided a better understanding of the mineralogy. This includes characterisation of a perovskite type phase, not previously identified because of its similarity (structure and composition) to brownmillerite. New SEM and TEM studies are presented in this paper. Comparisons of these analyses make it possible to obtain a new and coherent description of the mineralogical composition of this category calcium aluminate cement.