PREPARATION OF AQUEOUS DISPERSION CONTAINING SILICA FUME

PURPOSE:To make it possible to form an aqueous dispersion wherein a strong grinding or shearing force is applied on a silica fume in a mixture, by mixing water and the silica fume at a predetermined ratio and, if necessary, adding a dispersing agent and then carrying out a high speed grinding treatment. CONSTITUTION:Water and a silica fume are mixed at a predetermined ratio. A rotating shaft 3 is fixed in a center hole 2 of an impeller blade 1 on the circumference of which notches 1a, 1a are attached and the mixture 5 of the silica fume and water in a cylindrical tank 4 is ground by rotating this rotating shaft 3 with high speed. By this treatment, the mixture of the silica fume and water is circulated by means of the impeller blade 1 as shown by allow marks A and B and the silica fume is thereby strongly ground and uniformly mixed to obtain an aqueous dispersion having a specified viscosity. Occurrence of partial agglomeration phenomenon of the silica fume which is an extremely fine amorphous silicic acid can be thereby prevented, uniform miscibility of cement can be furthermore improved, a pozzolan reaction in the cement is accelerated and fine voids in the cement is uniformly filled.