Transformation of Calcium Silicate Hydrates to Tobermorite
Author Information
Author(s): Jacqueline R Houston, Robert S Maxwell, Susan A Carroll
Primary Institution: Lawrence Livermore National Laboratory
Hypothesis
What are the reaction rates and mechanisms for the growth of tobermorite from calcium silicate hydrates in the absence of CO2?
Conclusion
The study found that tobermorite growth rates are faster when the solution volume is reduced, indicating that reaction rates depend on solution saturation.
Supporting Evidence
- Reaction rates for tobermorite growth were found to be faster with a solution:solid ratio of 5:1 compared to 10:1.
- NMR spectroscopy revealed two distinct aluminum coordination sites in the tobermorite structure.
- XRD data indicated that tobermorite growth is nearly complete after 3 days at a solution:solid ratio of 10:1.
Takeaway
This study looks at how a type of cement changes into a more stable form when mixed with water, and it shows that using less water makes this change happen faster.
Methodology
Batch experiments were conducted at 150°C with solution:solid ratios of 10:1 and 5:1, analyzing the resulting solids using XRD and NMR spectroscopy.
Limitations
The study did not sample the reactive pore water within the Al-CSH layer, which may affect the understanding of the reaction mechanisms.
Digital Object Identifier (DOI)
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