Silica fume, also called Microsilica, is a byproduct of producing silica metal or ferrosilicon alloys. silica metal and alloys are produced in electric furnaces. The smoke that results from furnace operation is collected and sold as Silica fume, rather than being landfilled. Silica fume consists primarily of amorphous (non-crystalline) silicon dioxide (SiO2), its average granule diameter is 0.15~0.20 µm, specific surface area is 15000~20000 m2/kg, and it has extremely strong surface active.
Grey to medium grey powder
Loss on ignition
Retained on 45micron sieve
Pozzolanic Activity Index
Silica fume in refractory
1.Silica fume Enhancing the fluid of pouring refractory, reducing the volume of used water, be easy to shape, and raising the production efficiency.
2.Because of its untramicrostructure for gap filling, the compact and intensity of refractory gain rising by a wade margin.
3. Silica fume is a highly effective pozzolanic material, so it's easy to come into being Mullite Phase, under the premise that Al2O3 exists, enhance elevated temperature strength and thermal shock of refractory.
Silica fume in Concrete
The uses for Silica fume in concrete fit into general categories of enhancing mechanical properties, improving durability, enhancing construct ability.
1.Silica fume Makes high-grade concrete effectively enhances the strength and pumpability of strong concrete.
2.Making high crack-resistance, self-waterproofing concrete, Silica fume be used in the subway, tunnel and basement of high-rise structures.
3.Used in maritime works and chemical industry. Owing to the compactability, Silica fume can prevent effectively sulphate and chlorine ion from osmosizing and eroding Avoid the steel corroding in armoured concrete (RC), lengthen the life-span of concrete.
5. In project item for water conservancy and bridge, the concrete not only needs basic quota mentioned above, but also its wear-resistant quality and abrasion resistance. Thus, adding Silica fume is necessary.
7. Silica fume used in the construction item under water, such as pier, huge dam and drilling platform.
8. Silica fume used in road surface concrete of expressway and large-scale bridge.
Because of its fine particles, large surface area, and the high SiO2 content, Silica fume is a very reactive pozzolan when used in concrete. At the same time, Silica fume can still be used in the production of refractory and porcelain; to raise intensity and durability .