The effect of gaseous SO2 secondary sintering on the cement composition and crystal structure.

• The Portland cement clinker was modified in a sintering atmosphere containing SO 2. • SO 2 could affect the content and structure of alite in Portland cement clinker. • SO 2 could change the grain size and micromorphology of alite. • The clinker sintered in SO 2 atmosphere had higher hydration activity. This paper explored the influence of gaseous SO 2 at different temperatures on the composition and structure of the secondary sintered cement clinker. The combination of X-ray powder diffraction (XRD) and rietveld refinement was used to study the composition and content changes of clinker phase. The morphology and clinker sintering history of the clinker phase were determined by the petrographic analysis. The structure of alite was identified by XRD and transmission electron microscopy (TEM) analysis. The experimental results showed that the presence of gaseous SO 2 promoted the decomposition of alite and increased the value of M1-alite%/(M1-alite% + M3-alite%). The hydration exothermic curve showed that the activity of M1-alite was higher than that of M3-alite. [ABSTRACT FROM AUTHOR]