Abstract
Due to the nanocrystallinity of the calcium-silicate-hydrate (C-S-H) gel in ordinary Portland cement-based paste combined with the presence of nanoscale heterogeneities such as varying calcium-to-silicon ratios and incorporation of aluminum in the structure, standard characterization techniques fail to fully capture the complex atomic structure and nanoscale morphology of this important binder phase. Here, neutron pair distribution function (PDF) analysis is applied to a range of deuterated C-S-H gels with varying Ca/Si ratios (denoted C-S-D). In situ temperature measurements reveal that the local atomic bonding environments in C-S-D gel undergo large structural rearrangements due to exposure to elevated temperature (above ∼ 200°C), including the collapse of the C-S-D gel interlayer spacing to 9.6 Å and the emergence of a disordered dicalcium silicate phase (similar to larnite). At lower elevated temperatures, the atom-atom correlations are dominated by scattering from deuterium atoms and therefore can be used to quantify the dehydration kinetics.
Original language | English (US) |
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Pages (from-to) | 93-100 |
Number of pages | 8 |
Journal | Cement and Concrete Research |
Volume | 79 |
DOIs | |
State | Published - Jan 2016 |
All Science Journal Classification (ASJC) codes
- Building and Construction
- General Materials Science
Keywords
- Calcium-silicate-hydrate (C-S-H) B
- Characterization B
- Neutron pair distribution function
- Stability C
- Temperature A