CHARACTERISTICS OF SILICA FUME 1. Physical Properties Diameter is about 0.1 micron to 0.2 micron Surface area about 30,000 m²/kg Density varies from 150 to 700 kg/m³ When its density is about 550 kg/m³ it is the best suited as concrete additive 2. Chemical Composition Contains more than 90 percent silicon dioxide Other constituents are(…)