Hydration Characteristics of Tricalcium Aluminate in the Presence of Nano-Silica
1
Key Laboratory for Resilient Infrastructures of Coastal Cities (Ministry of Education), Underground Polis Academy, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China
2
Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
3
School of Architecture and Built Environment, The University of Newcastle, Callaghan, NSW 2308, Australia
*
Author to whom correspondence should be addressed.
Nanomaterials 2021, 11(1), 199; https://doi.org/10.3390/nano11010199
Received: 4 December 2020
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Revised: 7 January 2021
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Accepted: 12 January 2021
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Published: 14 January 2021
(This article belongs to the Special Issue Silica and Silicon Based Nanostructures)
Tricalcium aluminate (C3A) 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-SiO2) 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 C3A needs to be well understood. In this study, the hydration kinetics of C3A mixed with different percentages of nano-SiO2 were studied and compared with pure C3A. 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-SiO2 promoted the conversion of the intermediate product C4AH13. The isothermal calorimetry results showed that the addition of nano-SiO2 significantly reduced the hydration exotherm rate of C3A from 0.34 to less than 0.1 mW/g. With the presence of nano-SiO2, the peaks for Q1 were observed in 29Si MAS-NMR measurements, and the content of Q1 increased from 6.74% to 30.6% when the nano-SiO2 content increased from 2 wt.% to 8 wt.%, whereas the proportion of Q4 gradually decreased from 89.1% to 63.6%. These results indicated a pozzolanic reaction provoked by the nano-SiO2 combined with aluminate structures generating C-A-S-H gel.
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Keywords:
nano-silica; tricalcium aluminate; pozzolanic reaction; C-A-S-H gel
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MDPI and ACS Style
Zheng, D.; Monasterio, M.; Feng, W.; Tang, W.; Cui, H.; Dong, Z. Hydration Characteristics of Tricalcium Aluminate in the Presence of Nano-Silica. Nanomaterials 2021, 11, 199. https://doi.org/10.3390/nano11010199
AMA Style
Zheng D, Monasterio M, Feng W, Tang W, Cui H, Dong Z. Hydration Characteristics of Tricalcium Aluminate in the Presence of Nano-Silica. Nanomaterials. 2021; 11(1):199. https://doi.org/10.3390/nano11010199
Chicago/Turabian StyleZheng, Dapeng, Manuel Monasterio, Weipeng Feng, Waiching Tang, Hongzhi Cui, and Zhijun Dong. 2021. "Hydration Characteristics of Tricalcium Aluminate in the Presence of Nano-Silica" Nanomaterials 11, no. 1: 199. https://doi.org/10.3390/nano11010199
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