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Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates
Elizaveta Pustovgar1, Rahul P Sangodkar2, Andrey S Andreev3
1Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich 8093, Switzerland.
Nature Communications
|March 25, 2016
Summary
This study uses advanced NMR to track tricalcium silicate hydration, revealing how surface passivation influences the rate of calcium-silicate-hydrate formation.
Area of Science:
- Materials Science
- Chemistry
- Geology
Background:
- Silicate hydration is crucial in natural and industrial processes.
- Tricalcium silicate (Ca3SiO5) is a key component of Portland cement.
- The hydration mechanism of Ca3SiO5 remains incompletely understood.
Purpose of the Study:
- To quantitatively monitor the hydration of tricalcium silicate.
- To elucidate the factors influencing the hydration rate.
- To analyze the molecular structure of calcium-silicate-hydrates (C-S-H).
Main Methods:
- Solid-state nuclear magnetic resonance (NMR) spectroscopy.
- (29)Si-enriched triclinic Ca3SiO5.
- Monitoring transient local molecular composition, silicate hydration, and polymerization.
Main Results:
- Quantitative insights into silicate hydration and polymerization.
- Demonstration of surface passivation during the deceleration stage of hydration.
- Measurement of monomer, dimer, pentamer, and octamer quantities in C-S-H.
Conclusions:
- Surface hydroxylation and hydrate precipitation influence hydration rate.
- Partial surface passivation occurs as the hydration rate drops.
- Detailed molecular-level understanding of C-S-H formation is achieved.
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