Silica fume
Description
Silica fume (CAS 69012-64-2) is an ultrafine industrial byproduct collected during silicon and ferrosilicon alloy production. It functions as a pozzolanic binder and rheology modifier in cementitious systems.
The material reacts with calcium hydroxide to densify matrix microstructure in various applications. In high-performance concrete, it is incorporated to reduce permeability and increase compressive strength.
This makes it the material of choice for bridges, marine structures, and tunnel linings. Refractory manufacturers use it to improve castable flow and sintered density in furnace linings and ladles.
These components operate under extreme thermal conditions in industrial settings. In mining, it is added to shotcrete mixes to accelerate early strength gain and reduce rebound loss in underground support.
Pulp and paper facilities use the product in cementitious flooring and containment structures. This is particularly useful where chemical resistance and durability are critical for long-term operations.
The product is supplied as a dry densified powder or undensified powder. Densified grades are often preferred for bulk handling and reduced dusting during the manufacturing and mixing process.
It is also available as a slurry for direct addition to ready-mix concrete operations. Standard grades conform to ASTM C1240 and EN 13263 specifications for industrial use.
These standards define minimum SiO₂ content and physical requirements for use in concrete applications. This ensures consistent performance and quality across various construction and refractory projects.
Physical Properties
| Density | 0.45-0.67[at 20℃] |
| Appearance | Amorphous silica, the noncrystalline form of SiO2, is a transparent to gray, odorless, amorphous powder |
| Form | Fine white powder with particle sizes generally below 1mm. This is not the same as the commercial products “fumes silica,” “silica gel,” “precipitated silica,” or “fused silica.” It is formed during the electric arc production of elemental silicon from quartz, which is reduced to silicon monoxide, escaping from the furnace and oxidized by air to silicon dioxide. This condenses to form spherical particles. For the production of ferrosilicon, iron metal is added to the charge; during charging there is also exposure to crystalline silica. |
| Water Solubility | 135mg/L at 37℃ |
Documentation
Other Names
Amorphous silica fume|Fumes, silica
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