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

Abstract

The importance of computed X-ray diffraction patterns of various polymorphs of alite (M 3 , T 1 , R), belite (β, γ), 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 β-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. β-C 2 S/C 3 S ratio, fraction of finer cement particles present in the samples and theoretical modeling of C 3 S hydration.

Studies on early stage hydration of tricalcium silicate incorporating silica nanoparticles: Part II

“…Further, XRD results reveal the crystalline nature of C-S-H in the presence of SNPs. As discussed by Taylor [41], XRD pattern from ordered jennite and tobermorite have maxima at 1.8 Å (2h = $50.7) [41,42]. In pure C 3 S hydrated samples this peak appeared at 15 h and remains Intense Q 2 peak ($ 1101 cm À1 ) of silicate chain [46] is observed at 6 h, Fig.…”

“…XRD results also show the existence of nucleation effect at early stage of hydration (up to 10 h). The intensity of crystalline CH peak at 2h = 18.02 [42] increases regularly up to 24 h show the natural nucleation effect of hydrated products formed in pure samples. In SNPs incorporated C 3 S samples the intensity of CH peak is observed to be higher than that of pure C 3 S up to 10 h, Fig.…”

“…Detailed XRD studies were carried out for pure and SNPs incorporated hydrated C 3 S system. In pure C 3 S samples the intensity of crystalline CH peak at 2h = 18.02 [42] is regularly increased with the hydration up to 24 h, Fig. 4a showing the growth of hydrated products during acceleration and deceleration period.…”

Studies on early stage hydration of tricalcium silicate incorporating silica nanoparticles: Part I

“…Each peak shift and intensity was monitored and carefully analyzed. Characteristic peak of the unhydrated C 3 S (2 h = $32) gets overlapped with the C-S-H peak in hydrated samples [36]. In hydrated C 3 S samples, the intensity of this peak decreases as hydration proceeds up to 1:00 h, showing the dissolution of C 3 S with the time (Fig.…”

“…8a) indicating that at this point the concentration of ions reaches to its supersaturation level. Thus, crystallization of CH takes place, which can be correlated with the ending of dormant period and start of the acceleration period [36,14,16]. On the other hand, in the case of nano silica incorporated hydrated C 3 S; this peak appeared at 3:00 h of hydration showing the shift in the Ca 2+ supersaturation state, i.e.…”