Synthesis and characterization of mineral phases C₃S, C₂S, C₃A and C₄AF for use in Portland cement

The main phases contained in the Portland cement are 3CaO.SiO₂ (C₃ S), 2CaO.SiO₂ (C₂ S), 3CaO.Al₂O₃ (C₃ A), and 4CaO.Al₂O₃ . Fe₂ O₃ (C₄ AF). In the industrial process, these phases present incorporations of other elements that depend on the raw materials and the fuels used in the firing. The use of the pure phase helps in understanding the phenomena involved in the fresh and hardened state, however their isolated production requires specific conditions. The objective of this research was to perform the synthesis of the phases in order to obtain the minimum of polymorphs and CaO. In the characterization of the chemical phases obtained, the laser particle-size analysis, X-ray fluorescence and X-ray diffraction with the quantification by Rietveld method were used. High purity could be obtained for C₄AF and C₃A. The C₃S and C₂S phases had at most one polymorph, but high levels of CaO, 4.9 and 5.1%, respectively. (author)