Computation of X-ray powder diffractograms of cement components and its application to phase analysis and hydration performance of OPC cement

The importance of computed X-ray diffraction patterns of various polymorphs of alite (M-3, T-1, R), belite (beta, gamma), aluminate (cubic, orthorhombic), aluminoferrite, gypsum and hemihydrate in the quantitative phase analysis of cement and its early stage hydration performance is highlighted in this work with three OPC samples. The analysis shows that the predominant silicate phases present in all the samples are M-3-alite phase and beta-belite phase, respectively. Both cubic and orthorhombic phases of C(3)A, brownmillerite, gypsum and hemihydrates are present at different levels. Quantitative phase analysis of cement by Rietveld refinement method provides more accurate and comprehensive data of the phase composition compared to Bogue method. The comparative hydration performance of these samples was studied with w/c ratio, 0.5 and the results are interpreted in the light of difference in phase compositions viz. beta-C2S/C3S ratio, fraction of finer cement particles present in the samples and theoretical modeling of C3S hydration.