Early reactivity of sodium silicate-activated slag pastes and its impact on rheological properties. (February 2021)

• Record Type: Journal Article
• Authors: Palacios, M.; Gismera, S.; Alonso, M.M.; d'Espinose de Lacaillerie, J.B.; Lothenbach, B.; Favier, A.; Brumaud, C.; Puertas, F.
• Is Part Of: Cement and concrete research. Volume 140(2021)
• Publication Date: 2021-02
• Subjects: Alkali-activated slag cement -- Sodium silicate activator -- Rheology -- Reaction -- Thermodynamic calculations; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2020.106302
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: The fast loss of fluidity of sodium silicate-activated slag (SS-AAS) systems have been widely studied in the literature. In this study, the rheology of these cements has been correlated with the evolution of the reaction products formed over time. For this purpose, a combination of experimental characterization techniques, to study the pore solution composition and microstructure of SS-AAS pastes and thermodynamic calculations have been applied. The initial precipitation of ill-defined N-A-S-H and C-N-A-S-H producta leads to a fast increase of the storage modulus after 40 min of reaction. These products are formed from the reaction of the Na + ions and silicate ions of the activator with the Ca 2+ and aluminate species dissolved from the slag. However, when a shear is applied, the structure breaks down and fluidity is recovered, that infers that the attractive forces between the particles are low at the early stages of hydration.