The main applications of microsilica powder
Micro-silica powder, also known as silica ash, is a dust recovered from the flue gas of alloy smelting such as silicon metal or ferrosilicon. The average particle size of micro-silica powder is 0.2um, and the specific surface area is 15000-25000 m2/kg. Its main component is silicon dioxide, with 85%-95% content, and the impurity components are sodium oxide, sodium oxide, calcium oxide, iron oxide, aluminum oxide and other metal oxides and a small amount of singlet carbon and silicon, etc.Since silica in microsilica powder is an amorphous substance with high activity, fine particles, large specific surface area and excellent physical and chemical properties, it used to be considered as an industrial waste, but now it is increasingly considered as a valuable resource, a kind of superfine powder without crushing processing and cheap, which can be widely used in concrete, refractory materials, wall materials, cement products, mortar, flooring, chemical industry and other important fields used in special projects.
Micro-silica powder is specifically summarized in the following areas of application.
1、Micro-silica powder is used as an additive in refractory materials
China is the world's largest consumer of refractories, and the application technology of Sanyuan microsilica powder in refractories is relatively mature, especially high-quality microsilica powder has the characteristics of high fluidity, low water storage, high denseness and high strength. It is mainly used as high performance refractory castables, prefabricated parts, ladle materials, breathable bricks, self-flowing refractory castables and dry and wet spraying materials. As well as oxide bonded silicon carbide products, high temperature type calcium silicate light insulation materials, corundum mullite push plate for electromagnetic kilns, high temperature wear resistant materials and products, corundum and ceramic products, etc.
2, micro-silica powder for concrete high-strength admixture
Concrete industry is the earliest research in foreign micro-silica powder comprehensive utilization, the most achievements, the most widely used in a field. As micro-silica powder has fine particles, large specific surface area, high purity of SiO2, volcanic ash activity and other physical and chemical characteristics, the micro-silica powder as a mixer added to concrete can improve the performance of concrete in many aspects, such as significantly improve the adhesion properties of plastic concrete and cohesion, significantly reduce the amount of rebound, increase the thickness of shotcrete once formed, shorten the construction period, save the cost of the project.
In the field of ordinary high-performance concrete and ultra-high-performance active powder concrete, micro-silica powder as an admixture to formulate high-strength concrete, its strength grade can reach hundreds of MPa or more. For example: RPC concrete, HPC concrete, pipe pile concrete, etc.
3、Micro-silica powder is the admixture of blended cement
In 1982, Lafarge Cement Company of France used micro-silica powder mixed with Portland clinker to produce blended cements into the market. Generally, micro-silica powder made into spheres is ground together with clinker to produce blended cement containing about 6% micro-silica powder. At present, certain special areas of domestic cement, has been widely added micro-silica powder system mixed cement or special cement.
4、Micro-silica powder is the main material of external wall insulation STP hollow insulation board
Using the characteristics of low density, low moisture drying, fine fineness and good adhesion of the initial product of Sanyuan silica fume, the silica fume (and other auxiliary materials) is sealed according to the shape of a certain size area of the wall material, airtight and compressed, and drawn into the hollow. Silica fume as inorganic non-metallic materials, thermal conductivity is very low, made of hollow insulation board has a lighter, more energy-saving insulation characteristics.
5、Micro-silica powder is a common additive for mortar, pressure grout, grouting material, etc.
Wall energy saving, insulation, fire prevention is the industry hotspots in recent years, therefore, insulation mortar, foamed concrete panels and aerated concrete are stand out. Silica fume as to improve the strength, fluidity aspects are also evident in these product applications.
At the same time, in recent years, with the rapid development of high-speed railway technology and construction needs, through the improvement of grout technology, the use of cement + fly ash + silica fume + cellulose + defoamer + water reducing agent + expansion agent, etc., developed into super self-flowing, high-strength, dense pore pressure grout. This technology has become increasingly mature and has been widely used in the field of highways, bridges and high-speed railways.
