Chemical effect of nano-alumina on early-age hydration of Portland cement

By Jin Zhou, K. Zheng, Zanqun Liu, F. He. Cement and Concrete Research, 2019

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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 (C3A). 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.

Subfields: Civil and Structural Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/902f0238e4a18542ffc7c8049af99958a5e52261