Hydration of a low-alkali CEM III/B-SiO{sub 2} cement (LAC)
- Empa, Laboratory for Concrete and Construction Chemistry, CH-8600 Duebendorf (Switzerland)
- PSI, Laboratory for Waste Management, CH-5232 Villigen PSI (Switzerland)
The hydration of a low-alkali cement based on CEM III/B blended with 10 wt.% of nanosilica has been studied. The nanosilica reacted within the first days and 90% of the slag reacted within 3.5 years. C-S-H (Ca/Si {approx} 1.2, Al/Si {approx} 0.12), calcite, hydrotalcite, ettringite and possibly straetlingite were the main hydrates. The pore water composition revealed ten times lower alkali concentrations than in Portland cements. Reducing conditions (HS{sup -}) and a pH value of 12.2 were observed. Between 1 month and 3.5 years of hydration more hydrates were formed due to the ongoing slag reaction but no significant differences in the composition of the pore solution or solid phase assemblage were observed. On the basis of thermodynamic calculations it is predicted that siliceous hydrogarnet could form in the long-term and, in the presence of siliceous hydrogarnet, also thaumasite. Nevertheless, even after 3.5 year hydration, neither siliceous hydrogarnet nor thaumasite have been observed.
- OSTI ID:
- 21596959
- Journal Information:
- Cement and Concrete Research, Journal Name: Cement and Concrete Research Journal Issue: 2 Vol. 42; ISSN 0008-8846; ISSN CCNRAI
- Country of Publication:
- United States
- Language:
- English
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