EFFECTS OF SOL-GEL DERIVED NANO-SILICA SUSPENSIONS IN CEMENT PASTE

摘要

One challenge of the use of nanoparticles in concrete has been agglomeration and dispersion. In this study, silica nanoparticles were synthesized via sol-gel using tetraethylorthosilicate (TEOS) as the precursor and ammonium hydroxide (NH_4OH) as the gelation catalyst. The composition and particle size distribution of the resulting powder were examined by energy-dispersive X-ray spectroscopy (EDS) and particle size analysis (PSA), respectively. It was found that ammonium hydroxide delayed the setting time of cement, thus the suspension was thoroughly rinsed with a solution of Ca(OH)_2 in distilled water. The suspension of nanoparticles in Ca(OH)_2 solution was directly incorporated into the cement and water mixture to make the cement paste. Setting time and heat of hydration of cement were compared for cement pastes with the nanoparticles as suspension, as dried particles and control specimens. Results indicate that direct incorporation of nano-silica as an aqueous suspension has potential benefits.