Influence of silica nanoparticles on the strength characteristics of cement samples

Abstract

The influence of silica nanoparticles on the properties of systems of the cement-sand-water type was investigated experimentally. Nanoparticles were separated from natural hydrothermal solutions according to the two-stage technological scheme including membrane concentration and cryochemical vacuum sublimation drying of silica sols with the preparation of nanopowders. Silica nanopowders with a particle size of 10–100 nm, a specific surface area of 100–400 m2/g, and an average pore diameter of 3–10 nm were introduced into the cement-sand-water system in amounts of 0.001–0.200 wt % with respect to concrete. The nanopowders were mixed with water intended for tempering cement to obtain a stable suspension with a uniform distribution of particles over the volume, which was introduced into the mixture of cement and sand. The characteristics of the solid samples were measured at different ages from 3 to 28 days. It was established that the nanoadditive affects the density, the rate of strength development, and the final compressive strength of cement samples.