Dicalcium silicate doped with sulfur

Abstract

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.

Incorporation of antimony‐bearing mining wastes into clinker Portland raw feed: The difficulty of Sb analysis in calcium silicates

“…The chemistry of the phases is strongly influenced by the waste input in the raw feed and their content in foreign elements is likely to strongly affect their reactivity. Sulphur, for instance, is present in both belite and alite from the present study; it is known to enhance belite hydraulicity 30 …”

“…Sulphur, for instance, is present in both belite and alite from the present study; it is known to enhance belite hydraulicity. 30 The preservation of metallic phases as inclusions in the clinker's silicate show that they are not totally incorporated, however, their round shape indicates a partial reaction during the growth of the phases. The EDS analysis of the silicates reveals very low concentrations of metallic impurities, which is in good agreement with the low amount of mine waste added to the raw feed.…”

Research review of cement clinker chemistry

“…Other researchers found that SO 3 promotes C 2 S formation at the expense of C 3 S [14,15]. It was documented that an SiO 2 substitution by SO 3 of up to 4.4 wt.% stabilizes monoclinic β-C 2 S. By this mechanism the hydraulic activity increases up to 3 times with respect to the pure β-C 2 S [62]. This result is in contrast to observation that increasing sulfur additions decreases hydraulic reactivity of β-C 2 S [26,36].…”

The good, the bad and the ugly polishing: Effect of abrasive size on standardless EDS analysis of Portland cement clinker’s calcium silicates

“…Even though calcium silicate in Portland cement clinker has been well known for decades, their microanalysis is still of interest nowadays. EDS can be performed for example as an educational tool in order to illustrate Ca/Si ratios or in routine quality control as well as when incorporating various foreign elements in belite (Staněk and Sulovský, 2012).…”