Mineralogical analysis of Brazilian Portland cements by the Rietveld method with emphasis on polymorphs M1 and M3 of alite

Eight samples of Portland cement and a clinker provided by the Brazilian Association of Portland Cement were analysed with different laboratory diffractometers and a synchrotron instrument to determine the statistical variability in the determination of the mass percentage of the main crystalline phases. Five laboratories participated in the experiment. Data collection was performed by each laboratory following its own internal procedures for a standard Rietveld analysis of mineral phases. Both Cu and Mo radiations were used. Reflection geometries—with and without sample rotation—and transmission geometries were also used. The synchrotron diffraction pattern was acquired from a rotating capillary and a wavelength of 0.41290 Å. Analysis of all diffraction patterns was performed with the help of TOPAS Academic v. 6 with the specific purpose of determining the proportions of polymorphs M1 and M3 of alite, since their ratio must be taken into account for the subsequent development of the mechanical properties of concrete.