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The influence of nano-SiO2 emulsion on sulfate resistance of cement-based grouts

Li Shuiping, Yuan Bin, Cheng Jian, Yu Xiaocheng, Wei Chao, Wu Qisheng, Zhang Youchao

Materials Science Poland

2024

Vol. 42, No. 1

116--125

Sulfate attack is one of the most significant durability issues for cement-based grouts, which are widely used to repair concrete structures in sulfate-rich environments. The purpose of this study was to investigate the impact of nano-SiO2 emulsion on the sulfate resistance of cement-based grouts. The durability of the mixes was evaluated on the basis of weight loss and compressive strength. X-ray diffraction (XRD) and scanning electron microscopy (SEM) of hardened grout matrix were used to analyze the hydration products and microstructure of the hardened grout matrix. The results indicate that the hydration degree of nano-SiO2-modified samples is higher than that of the control sample. The compressive strength from highest to lowest was 16 NSE, 10 NSE, NSP, and the control sample. The XRD and SEM results suggest that the deterioration of properties may be attributed to the formation and growth of ettringite (AFt) crystals, which may result in crack generation and extension and in the corrosion of gypsum, leading to exfoliation. The addition of nano-SiO2 to cement-based grouts through a preprepared emulsion, which facilitates dispersion within the cement matrix, has the potential to reduce AFt and gypsum contents, enhance microstructure density, decrease the migration channels of SO4-2, and ultimately improve the resistance to sulfate attack. This work will provide a novel route to enhance the sulfate resistance of cement-based grouts, which may be serviced in a sulfate-rich environment.

Study on the effect of nanosilica suspension on the properties of cement-based grouts

Li Shuiping, Chao Wei, Li Wei, Cheng Jian, Yuan Bin

Materials Science Poland

2022

Vol. 40, No. 4

171--182

The agglomeration trend of nanosilica particles was found to significantly affect the properties of cement-based materials. The influence of nanosilica suspension on the fluidity, setting time, and compressive strength of cement-based grouts were studied. The hardened pastes were characterized by thermogravimetric (TG) analysis and scanning electron microscopy (SEM). The results showed that the fluidity of cement-based grouts with nanosilica suspension had obviously improved. The setting time was obviously decreased, compared with the reference sample. The compressive strengths for 1 day, 3 days, and 28 days were 12.8%, 14.3%, and 10.1% higher than that of the reference group, respectively. This paper may provide a novel route to improve the mechanical properties of cement-based materials without affecting their workability.