In situ Raman analysis of hydrating C(3)A and C(4)AF pastes in presence and absence of sulphate

Raman spectroscopy has been used to follow the hydration of C(3)A and C(4)AF, two of the principal components of ordinary Portland cement (OPC), in the absence and presence of calcium sulphate ( gypsum). Raman spectroscopy enabled in situ, real time analysis of the hydrating pastes. Analysis of the pastes by X-ray diffraction complemented the Raman data and confirmed sample composition. Subtle changes in the Raman spectra of the different pastes illuminated differences in hydration behaviour between C(3)A and C(4)AF. The similarities and differences between the various systems are discussed. The influence of carbon dioxide on the hydration products has also received attention.