Synthesis of M1 and M3 alite polymorphs and accuracy of their quantification

Although much attention has been paid to the phase analysis of cementitious materials and X-ray diffractometry is nowadays a common tool of quality control, the identification of alite polymorphs is still problematic. A procedure for the laboratory synthesis of monoclinic alite polymorphs in quantities of tens to hundreds grams using mechano-chemical activation and solid-state synthesis was proposed. M1 and M3 alite with a purity of 98 % and 99 % respectively were produced. In order to make the XRD identification in industrial clinkers easier, mixtures of defined ratios of these phases were prepared and generally applicable diffractogram standards were generated. Accuracy of the quantification results via the Rietveld method was verified using the industrial clinker samples with the minor addition of both polymorphs. The profile of the selected reflections is significantly affected by the contents of about 5-10 % of each polymorph.

Automated summary

Although X-ray diffractometry is commonly used for quality control, identifying alite polymorphs remains problematic. A laboratory synthesis method for monoclinic alite polymorphs was proposed, allowing for more accurate XRD identification in industrial clinkers.