Dicalcium silicate doped with sulfur

Dicalcium silicate (Ca₂SiO₄ or C₂S) containing foreign ions occurs as a component of Portland cement clinker and is called belite. Belite has a lower hydraulic activity than alite, which is the main component of Portland cement clinker. Belite can be prepared at lower expenditure and its hydraulic activation can have important impact on the economy and sustainability of the cement industry. This research focused on the activation of C₂S by incorporation of SO₃ into its crystal structure. This paper describes experiments with pure chemicals that characterise substitution of SiO₂ by SO₃ and its influence on the hydraulic activation of C₂S. It was confirmed that sulfur stabilises the monoclinic modification β-C₂S. The maximum content of SO₃ in C₂S under common laboratory burning conditions was approximately 4·4 wt%. The hydraulic activity of prepared β-C₂S doped with SO₃ was up to three times higher than in the reference non-activated β-C₂S.