SiO2 nanoparticles (50 nm in diameter) coated with poly(ethylene glycol) methyl ether methacrylate (PEGMA) were synthesized by radical polymerization. The SiO2/PEGMA nanocomposites were characterised using FITR, 1HNMR and TGA methods. The load of PEGMA in SiO2/PEGMA nanocomposites was 72.9 wt%. The hydration products, microstructure, pore structure, density, compressive strengths and rheological properties of cement were investigated. The SiO2/PEGMA nanocomposite could not only significantly improve the cement hydration and densify the microstructure by reducing the content of calcium hydroxide and promoting the production of calcium silicate hydrate, but also efficiently enhance the fluidity of the cement slurry. The compressive strength of cement with 2 wt% SiO2/PEGMA nanocomposites was increased by 40.1% curing for 28 days, which was much better than cement with the physical blending of SiO2 nanoparticles and superplasticizers. The SiO2/PEGMA nanocomposites with core-shell structure novelly combine the advantages of SiO2 nanoparticles and superplasticizers to significantly improve the performance of cement pastes. The results obtained provide a new understanding of the effect of the core-shell nanocomposites on cement pastes and demonstrate the potential of the nanocomposites for well cementing applications.
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