One of the most often and successfully applied admix as a part of the modified concrete is active amorphous silica fume. The increased practical interest in this admix has led to emergence in the market of various producers and also to emergence of different types (brands) of the silica fume produced from various raw materials with use of various technologies. At the same time their makeup, dispersion and content of silicone dioxide drastically ranges. It takes toll on results of use of such admixes in relation to the same recipes of concrete mixtures. The research is focused on the experimental study of the most useful types of active silica fume and the comparison of results of their using in fine-grained concrete. Results of these researches have shown a dependence of properties of the modified concrete on the content of active silica fume and from degree of its dispersion. The best results had silica fumes produced as the accompanying product by silicon production and including some additional quantity of particles of nanodimensional carbon.