Combining Raman Spectroscopy, DFT Calculations, and Atomic Force Microscopy in the Study of Clinker Materials

• Published in: Materials 2021-06, Vol.14 (13), p.3648
• Main Authors: Mohaček-Grošev, Vlasta, Đuroković, Marija, Maksimović, Aleksandar
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; Calcium carbonate; Carbon dioxide; Cement hydration; Clinker; Density functional theory; Dicalcium silicate; Gypsum; Humidity; Mapping; Mathematical analysis; Phonons; Portland cements; Raman spectroscopy; Scanning electron microscopy; Spectrum analysis; Tricalcium silicate
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14133648

Raman spectroscopy and Raman mapping analysis, combined with density functional theory calculations were applied to the problem of differentiating similar clinker materials such as alite and belite. The Portland cement clinker 217 (further: clinker) was analysed using colocalised Raman mapping and atomic force microscopy mapping, which provided both spatial and chemical information simultaneously. The main constituents found in the clinker were alite, belite, portlandite, amorphous calcium carbonate, and gypsum. Since phonon bands of alite and belite greatly overlap, and their distinction is important for the hydration process during cement setting, we provided the calculated phonon density of states for alite Ca SiO ( structure) and belite Ca SiO (β / structure) here for the first time. Both calculated phonon densities have similar distribution of phonon modes, with a gap between 560 and 810 cm . A comparison of the calculated phonon frequencies for Ca SiO and Ca SiO shows that the lowest calculated phonon frequency of β-Ca SiO lies at 102 cm , while for alite the lowest phonon frequency is predicted at 27 cm . Low frequency Raman spectroscopy could therefore be used for a clearer distinction of these two species in a clinker material.