Use of Nanosilica Recovered from the Finely Dispersed By-product of the Electrothermal Silicon Production for Concrete Modification

This research is focused on the study of a finely dispersed silica-containing by-product of the electrotermal silicon production obtained from the Irkutsk Aluminium Smelter. It consist of silica nanoparticles with the average size of 100 nm (52.6%), hydrophobic carbon black (44.6%) and other impurities. Nanosilica was recovered from the by-product by the flotation method and added to cement in different concentrations. The influence of nanosilica modifier on the concrete microstructure and strength properties was investigated. The microstructure and composition of modified and control concrete specimens were characterized by the scanning electron microscopy and X-ray diffraction. The mechanism for concrete strengthening is proposed. (C) 2016 Published by Elsevier Ltd.