1.Introduction :

Silica fume, also called as micro silica, silica dust, which is a by-product of producing silicon metal or ferrosilicon alloys. Silica fume consists primarily of amorphous (non-crystalline) silicon dioxide (SiO2). Because of its fine particles, large surface area, and the high SiO2 content, silica fume is a very reactive pozzolan when used in concrete. The quality of silica fume is specified by ASTM C 1240 and AASHTO M 307.

2.Application:

Silica fume is widely used in concrete field: High-performance project, such as bridge, airport, hydropowder station, seawall, railway projects.

1)Enhance the mechanical properties of concrete. 
High strength and early strength has been used in substructures of high-performance concrete.

2)Improve the durability of concrete:
Significant improvements can be seen in the permeability resistance, abrasion resistance, anti-corrosion against chlorideion and anti-freezing of concrete.

3)Enhance consructability.
Improve shotconrete, increase easly strength, control temperature contractors can take advantage of the properties of silica fume concrete to expedite projects or to achieve properties that migh otherwise be impossible to achieve.

3.Features:

1) High early strength.
2) Greater impermeability.
3) High ultimate compressive strengths.
4) Substantially greater resistance to corrosion.