Micro silica is silicon alloy and silicon smelting generated when SiO2 and Si gas and oxygen in the air and condensation to form the rapid oxidation of a fine silica powder.
First, micro-physical and chemical properties of silica fume:
1, micro silica fume: the appearance of gray or white powder, refractoriness> 1600 ?. Bulk density: 200 ~ 250 kg / cubic meter.
2, the fineness of micro-silica: silica fume in the fineness of less than 1?m, more than 80% of the average particle size of 0.1 ~ 0.3?m, specific surface area: 20 ~ 28m2 / g. The fineness and specific surface area of about 80 to 100 times of cement, fly ash, 50 to 70 times.
3, particle morphology and mineralogical structure: the formation process of silica fume, due to the process of phase transitions by surface tension effect, the formation of amorphous non-crystalline phase without spherical particles and the surface is smooth, while others are more round spherical particle aggregates stick together. It is a large surface area, active high ash material. Materials mixed with fine silicon powder, tiny spherical body can play Dunstable Aggregates the role of lubrication.
Second, role: micro silica powder to fill the pores between cement particles, hydration products and also generate gel, magnesium oxide reacts with the alkaline material gel. In the cement base of concrete, mortar and castable refractory, mixed with appropriate amount of silica fume, can play the following roles:
1, significantly improve the compressive, flexural, impermeability, corrosion, impact resistance and wear resistance.
2, with water to prevent segregation, bleeding, significantly reduced the role of the resistance of concrete pumping.
3, significantly extending the service life of concrete. Especially in the erosion of chloride contamination, sulfate attack, high humidity and other harsh environment, the durability of concrete can double or even several times.
4, a significant reduction in spraying concrete and castable floor dust, increase the thickness of a single spray.
5, is a necessary component of high strength concrete have been C150 concrete engineering applications.
6, with about 5 times the effect of cement, concrete and in the general application of low cement castables can reduce costs. To improve durability.
7, effectively prevent the occurrence of alkali-aggregate reaction of concrete.
8, increase the density of casting refractories. Coexist with Al2O3, the more likely generated mullite, its high temperature strength, enhanced thermal vibration.