Chemical effect of nano-alumina on early-age hydration of Portland cement. (February 2019)

• Record Type: Journal Article
• Authors: Zhou, Jin; Zheng, Keren; Liu, Zanqun; He, Fuqiang
• Is Part Of: Cement and concrete research. Volume 116(2019)
• Page Start: 159
• Page End: 167
• Publication Date: 2019-02
• Subjects: Chemical effect -- Hydration kinetics -- Nano-alumina -- Portland cement; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2018.11.007
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: For a full understanding of effects of nano-alumina on early-age hydration, hydration of a Portland cement blended with 5% of nano-alumina (γ-phase) was studied. Except for the well-known filler effect, a chemical effect of nano-alumina was identified in the study, which is related to its dissolving behavior in pore solution. The dissolution of nano-alumina leads to a high initial ettringite content even in the first 10 min, thus a higher initial heat release. The continuous dissolution of nano-alumina contributes to formation of additional ettringite, which consumes aqueous S species, promotes the depletion of gypsum, thus accelerating reaction of aluminate (C3 A). The dissolution of nano-alumina may also be influenced by S species in pore solution during the induction period. Afterwards, the slow dissolution of nano-alumina only results in a slightly increased aqueous Al concentration for the further increase would be limited by Al-bearing hydrates such as ettringite and AFm phases.