Title: Supersulphated Cements from Waste Materials

Author(s): Vlastimil Bilek s.r., David Bujdos, Michal Pesata, Lukas Vlastimil Prochazka, Vlastimil Bilek. j.r., Bohdan Sousedik

Publication: Symposium Paper

Volume: 355

Issue:

Appears on pages(s): 375-382

Keywords: fly ash, gypsum, GGBFS, supersulphated cement

DOI: 10.14359/51736045

Date: 7/1/2022

Abstract:
Supersulphated cements are considered to be some of the first alkali-activated cements. Ground granulated blast-furnace slag is activated with a small amount of Portland cement in the presence of gypsum, providing C-S-H gel and ettringite as the main reaction products. These materials exhibit some good properties; the most important of these being good sulphate resistance and also good environmental effects. Standard EN15743+A1 "supersulphated cement" describes the conditions for the composition of this binder. In this paper, the product after desulphurisation (PPR) from the Třebovice heating plant (Ostrava) was used as a source of gypsum. Strength development was recorded up to 91 days for different ratios of compounds. Early strengths are very low and are higher for higher ordinary Portland cement content. At 28 and 91 days of age, the strengths are almost the same for gypsum contents from 10 to 20% and all cement contents (2.5, 3.75, and 5%). These strengths are relatively high—around 50 MPa. Supersulphated cements can be a good choice for the use of waste material—the product after desulphurisation.