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Effect of Nano-SiO2 on the Hydration and Microstructure of Portland Cement

Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211800, China
Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil Engineering, Shenzhen University, Shenzhen 518060, China
Authors to whom correspondence should be addressed.
Academic Editor: Thomas Nann
Nanomaterials 2016, 6(12), 241;
Received: 7 November 2016 / Revised: 4 December 2016 / Accepted: 6 December 2016 / Published: 15 December 2016
This paper systematically studied the modification of cement-based materials by nano-SiO2 particles with an average diameter of about 20 nm. In order to obtain the effect of nano-SiO2 particles on the mechanical properties, hydration, and pore structure of cement-based materials, adding 1%, 3%, and 5% content of nano-SiO2 in cement paste, respectively. The results showed that the reaction of nano-SiO2 particles with Ca(OH)2 (crystal powder) started within 1 h, and formed C–S–H gel. The reaction speed was faster after aging for three days. The mechanical properties of cement-based materials were improved with the addition of 3% nano-SiO2, and the early strength enhancement of test pieces was obvious. Three-day compressive strength increased 33.2%, and 28-day compressive strength increased 18.5%. The exothermic peak of hydration heat of cement increased significantly after the addition of nano-SiO2. Appearance time of the exothermic peak was advanced and the total heat release increased. Thermogravimetric-differential scanning calorimetry (TG-DSC) analysis showed that nano-SiO2 promoted the formation of C–S–H gel. The results of mercury intrusion porosimetry (MIP) showed that the total porosity of cement paste with 3% nano-SiO2 was reduced by 5.51% and 5.4% at three days and 28 days, respectively, compared with the pure cement paste. At the same time, the pore structure of cement paste was optimized, and much-detrimental pores and detrimental pores decreased, while less harmful pores and innocuous pores increased. View Full-Text
Keywords: nano-SiO2; cement-based materials; physical and mechanical properties; porosity nano-SiO2; cement-based materials; physical and mechanical properties; porosity
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MDPI and ACS Style

Wang, L.; Zheng, D.; Zhang, S.; Cui, H.; Li, D. Effect of Nano-SiO2 on the Hydration and Microstructure of Portland Cement. Nanomaterials 2016, 6, 241.

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