Silica fume, also known as microsilica, whose main chemical component is SiO2, is a type of particle produced during the production of silicon metal or ferrosilicon, which floats in the exhaust gas and has a very small particle size, averaging only nanometers.
Silica fume mainly comes from among the waste gas produced during the production of silicon metal or ferrosilicon. Using professional equipment to filter the waste gas containing Silica fume, microsilica containing trace Si elements is sieved out, thus reducing the respirable matter in the waste gas, thus achieving the purpose of environmental protection and enhancing the benefits of manufacturers. The appearance of microsilica is a light gray ultra-fine powder that deepens in color as its internal C increases. Its nature is that it rapidly produces a gel-like substance after meeting water, so it is ideal for filling the gaps between concrete, thus improving the strength of concrete, and is therefore very widely used in large concrete projects. According to the chemistry of silica fume, it is found that microsilica contains mainly SiO2 elements and has very good fire resistance and high temperature resistance, which further enhances the safety of microsilica.
Just now when we introduced what is silica fume, we mentioned that silica fume has a wide range of applications in concrete engineering, in addition to that, microsilica has a wider range of applications.
Cement industry: Cement manufacturers will add microsilica in the process of producing cement, thus enhancing the performance of cement, and the cement standard is greatly improved.
Rubber industry: In the process of producing rubber products, microsilica is added to improve the elongation, tear resistance and anti-aging properties of rubber, and also has better dielectric properties.
Replacement of anti-caking agent: In the production of waste materials, silica fume can replace mica or diatomaceous earth to prevent caking of waste materials.
Alternative binder: Because of its larger surface area and better adsorption properties, microsilica is often used as a binder in the production of pellet ore, which is not only effective but also low in price.
Insulating material: Silica fume is widely used in the production of coatings, for example: waterproof paint, paint, ink, etc. are added to the production process, thus making itself have the insulation properties.
Many people ask why silica fume is used in concrete, but in fact, it is inextricably linked to a series of properties of silica fume. Microsilica has the advantages of producing a gel-like substance in contact with water, high temperature resistance, high density, high strength and insulating properties. In the process of high toughness concrete (C70 or above), adding silica fume can effectively improve the compressive strength and pumping performance of high toughness concrete. And when producing waterproof concrete with high impermeability grade (≥P30), Microsilica can effectively enhance the density and fill the gaps in the concrete, which is widely used in the construction of subway stations, tunnels, high-rise residential buildings and underground garages. On the other hand, since the particle size of microsilica can be reduced to nanometer level, it has strong compact type and good abrasion resistance, which can greatly improve the tensile strength, compressive strength and impact resistance of concrete after drying. After using silica fume in concrete, the wear resistance and durability of concrete are effectively improved by 0.5%~2.5%.
At present, many projects using concrete will add microsilica, so as to improve all aspects of the performance of concrete, especially in water conservancy projects, highways, highways and bridges and other concrete construction projects, which have strict requirements for its wear resistance, scour resistance and other properties, the addition of microsilica can effectively improve the life of the building, so it is very important to add silica fume in concrete.
In the construction sector, XLS Metlas silica fume have effectively improved the quality of various projects and have been praised for their reliability and effectiveness
| Chemical composition(%) | Grades | ||||
| SiO2 Min | 97 | 94 | 90 | 88 | 85 |
| Ai2O3 Max | 1 | 1 | 2 | -- | -- |
| Fe2O3 Max | 1 | 1 | 2 | -- | -- |
| CaO+MgO Max | 1 | 1 | 2 | -- | -- |
| K2O+Na2O Max | 1 | 1.5 | 2 | -- | -- |
| C Max | 1 | 2 | 2 | 2.5 | 3 |
| NaOH Max | 1 | 3 | 3 | 4 | 4.5 |
| PH Max | 4.5-6.5 | 4.5-7.5 | 4.5-7.5 | 4.5-8.5 | 4.5-8.5 |
| Size above 45um Max | 3 | 3 | 5 | 8 | 8 |
| Moisture Max | 0.1% Max | ||||
| M2/g Max | 1 | 2 | 2.5 | 3 | 3 |
Many people think that silica fume comes from waste gas and consider silica fume as waste. On the contrary, microsilica is not a waste material but an environmentally friendly product. As each country began to reawaken the importance of environmental protection, as a serious polluting industry, it became the object of treatment by the environmental protection department of each country. silica fume, as a product obtained after the treatment of exhaust gas, is itself an environmentally friendly product with small particle size, good adhesion, and high density, so it is widely used in construction projects such as concrete, cement, bridges, and hydroelectric power stations. It improves the feasibility of recycling and reuse, reduces impurities in the waste gas, and provides strong support for environmental protection.
Silica fume itself is not harmful. It is a highly active fine particle with an average diameter of only 0.2 microns, which is several times finer than the smoke exhaled by everyday smokers. However, because microsilica is a highly active fine particle, it can easily be inhaled and enter the eyes and respiratory tract, causing allergies and discomfort, and can also cause headaches, fever, chills, and coughs when exposed to large amounts, so you need to be well protected when exposed to microsilica. In the process of recycling silica fume, KN95-grade masks should be worn for the health of workers. When packing the silica fume, dustproof treatment should also be done to avoid the situation of pneumoconiosis after workers inhale the silica fume for a long time. At the same time, in the storage of microsilica, dustproof equipment should be prepared in the warehouse to avoid dust explosions caused by open flame or electric light.
