Hydration Characteristics of Tricalcium Aluminate in the Presence of Nano-Silica

Tricalcium aluminate (C A) is the most reactive component of the Portland cement and its hydration has an important impact on the workability and early strength of concrete. Recently, nanomaterials such as nano-silica (nano-SiO ) have attracted much attention in cement-based materials because of its...

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Bibliographic Details
Published in:Nanomaterials (Basel, Switzerland) Switzerland), 2021-01, Vol.11 (1), p.199
Main Authors: Zheng, Dapeng, Monasterio, Manuel, Feng, Weipeng, Tang, Waiching, Cui, Hongzhi, Dong, Zhijun
Format: Article
Language:English
Subjects:
C-A-S-H gel
Calcium aluminate
Calorimetry
Cement
Cement hydration
Heat measurement
Hydration
Magnetic resonance spectroscopy
nano-silica
Nanomaterials
Nanotechnology
NMR
NMR spectroscopy
Nuclear magnetic resonance
Portland cement
Portland cements
pozzolanic reaction
Scanning electron microscopy
Silica
Silicon dioxide
Tricalcium aluminate
Tricalcium aluminum ferrite
Workability
X ray photoelectron spectroscopy
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Summary:Tricalcium aluminate (C A) is the most reactive component of the Portland cement and its hydration has an important impact on the workability and early strength of concrete. Recently, nanomaterials such as nano-silica (nano-SiO ) have attracted much attention in cement-based materials because of its pozzolanic reactivity and the pore-filling effect. However, its influence on the hydration of C A needs to be well understood. In this study, the hydration kinetics of C A mixed with different percentages of nano-SiO were studied and compared with pure C A. The hydration products were examined by different characterization techniques including XRD, XPS, and NMR spectroscopy and isothermal calorimetry analyses. The XRD results showed that the addition of nano-SiO promoted the conversion of the intermediate product C AH . The isothermal calorimetry results showed that the addition of nano-SiO significantly reduced the hydration exotherm rate of C A from 0.34 to less than 0.1 mW/g. With the presence of nano-SiO , the peaks for Q were observed in Si MAS-NMR measurements, and the content of Q increased from 6.74% to 30.6% when the nano-SiO content increased from 2 wt.% to 8 wt.%, whereas the proportion of Q gradually decreased from 89.1% to 63.6%. These results indicated a pozzolanic reaction provoked by the nano-SiO combined with aluminate structures generating C-A-S-H gel.
ISSN:2079-4991
2079-4991
DOI:10.3390/nano11010199