Silica fume is a byproduct of the reaction between quartz and coal, coke, or wood chips and also forms in the production of silicon and ferrosilicon alloys. Silica fume is another silica-based additive used in cementitious applications. It is classified as ultrafine, with the size of spherical particles being less than 1 µm in diameter, 100 – 150 times smaller than an average cement particle. It acts as a pozzolan and filler when used in cementitious applications like concrete, repair products, and shotcrete. A pozzolan is a siliceous material with little or no cementitious composition. Silica fume is a byproduct of the reaction between quartz and coal, coke, or wood chips and also forms in the production of silicon and ferrosilicon alloys. Silica fume can be supplied with different densification levels, generally classified as unidentified (with a density of 130 kg/m3) to densified (600 kg/m3).
The surface area of silica fume can be measured with the BET or nitrogen adsorption method and typically ranges from 15 – 30 m2/g. When silica fume is added to Portland cement, its compressive strength, bond strength, and abrasion resistance are improved due to the excellent powder filling in cement gaps and the pozzolanic reaction between the silica fume and the free calcium hydroxide. It also reduces the concrete permeability to chloride ions, which protects steel-reinforced concrete from moisture and corrosion. With the addition of silica fume, workability, segregation, and bleeding in concrete are all improved. When mixed with concrete, silica fume transforms the cement paste’s structure. The result is high-strength calcium silicate hydrates and weaker, soluble, and fewer calcium hydroxides. The tiny particles make it easy to disperse and separate cement particles. This uniform matrix offers flexural, higher compressive, and bond strength. Bisley offers both densified and unidentified silica fume. If you are looking for high quality, high purity, and cost-effective Fumed Silica, or if you require the latest price of Fumed Silica, please feel free to email contact mis-asia.
