Exploring the potential of nano-SiO2 to prevent early-age frost damage in Portland cement paste

Exploring the potential of nano-SiO2 to prevent early-age frost damage in Portland cement paste

Bai, Shuai (Harbin Institute of Technology, China)
Guan, Xinchun (Harbin Institute of Technology, China)
Li, Hui (Harbin Institute of Technology, China)
Ou, Jinping (Harbin Institute of Technology, China)

2021-04-29

The purpose of this study is to explore the potential of nano-SiO2 (NS) to prevent early frost damage, and the effect of nano-SiO2 (NS) on cement pastes subjected to early-age freezing was investigated regarding the macro properties (strength and durability) and micro properties (hydration and microstructure). The specimens were prepared with NS content of 0%, 0.6%, 0.9% and 1.2% by weight of cement. The results indicated that nano-SiO2 has a positive impact on the macro properties of cement pastes frozen at early ages, compared with reference specimen. The cement pastes containing 0.9% NS achieved the best enhancements of 22.6% and 30.9% in compressive strength and chloride ion penetration, respectively. The TG results indicated that the additional nano-SiO2 particles can increase the hydration degree of cement paste and the MIP data indicated that nano-SiO2 particles reduced the total porosity and other pore structure parameters. This is because the additional C-S-H gels produced by the pozzolanic effect of nano-SiO2, and nano-filling of nano-SiO2 particles refine the pore structure of cement matrix. Moreover, XRD results showed that nano-SiO2 also reduce the Ca(OH)2 orientation in cement matrix.

Microstructure
Cement paste
Nano-SiO2
Early-age frost damage
Strength

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