Full phase analysis of portland clinker by penetrating synchrotron powder diffraction

Fabrication of portland cements commonly depends on X-ray fluorescence (XRF ), which measures the elemental compositions. XRF is used to adjust the raw material proportions and to control the process conditions. However, to pr edict the mechanical strength of the resulting concrete, it is essential to know the phase composition which is, so far, indirectly inferred by the Bo gue method. Here, we report a phase analysis of an industrial portland clin ker containing six crystalline phases, Ca3SiO5, Ca2SiO4, Ca4Al2Fe2O10, Ca3A l2O6, NaK3(SO4)(2), and CaO, by Rietveld refinement of synchrotron X-ray po wder diffraction data (lambda = 0.442 377 Angstrom), Even the minor compone nt, CaO 0.45(2)%, was readily analyzed. We have also carried out a phase st udy of the same clinker with laboratory X-rays to characterize the changes in the detection limit and errors. Furthermore, by adding a suitable crysta lline standard to the same clinker, we have determined the overall amorphou s phase content. The procedure established for this state-of-the-art phase analysis shows the high precision that can be achieved by using penetrating X-rays, which is of interest not only in cement chemistry but in other ind ustrially important multiphase systems such as slags, superalloys, or catal ysts.