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The synergistic effect of nano-SiO2 with silica fume in cement-based material

To understand the synergistic effect of nano-SiO2(NS) and silica fume (SF) on cement-based material, the hydration process, the compressive strength development, and the pore structure of cement-based materials with the addition of nano-SiO2 and SF were investigated. The results showed that the compressive strength of cement paste increased with the increase of NS, especially at the early ages. Compared with 10% SF, the incorporation of 3% NS in the cement pastes with 7%wt dosage of SF has the highest compressive strength (51.93 MPa). When replace SF with 3% NS, the hydration of cement was promoted, C–S–H gel increased as more calcium hydroxide was consumed. Three percent NS and 7% SF can significantly reduce the porosity of the cement matrix, which is also an explanation of the phenomenon of increased compressive strength.