Performance of Cement Systems with Nano-SiO 2 Particles Produced by Using the Sol–Gel Method

Abstract

The effect of 5- to 70-nm SiO₂ nanoparticles on the mechanical properties of nanocement materials was examined. The strength development of portland cement with nano-SiO₂ and superplasticizing admixture was investigated. Experimental results demonstrate an increase in the compressive and flexural strengths of mortars with SiO₂ nanoparticles. Because the distribution of nano-SiO₂ particles within the cement paste plays an essential role and governs the overall performance of these products, the addition of a superplasticizer was proposed to facilitate the distribution of nano-SiO₂ particles. The application of superplasticizer and high-speed dispergation were found to be effective disagglomeration techniques to improve the strength of superplasticized portland cement mortars, which reached up to 63.9 and 95.9 MPa (Sample 4B3, synthesized by using the sol–gel method in a base reaction medium at ethanol-to-tetraethoxysilane and water-to-tetraethoxysilane molar ratios of 24) at the ages of 1 day and 28 days, respectively. At corresponding ages, the compressive strength of reference portland cement mortars was 53.3 and 86.1 MPa. It is concluded that the effective dispersion of nanoparticles is essential to obtain composite materials with improved performance.