Silica fume is a highly pozzolanic material that is used to enhance mechanical and durability properties of concrete. It may be added directly to concrete as an individual ingredient or in a blend of portland cement and silica fume.
Interest in the use of silica fume resulted from the strict enforcement of air-pollution measures designed to stop release of the material into the atmosphere. Initial use of silica fume in concrete was mostly for cement replacement,along with water-reducing admixtures. Eventually,the availability of high-range water-reducing admixtures(superplasticizers) allowed new possibilities for the use of silica fume to produce high levels of performance.

Advantage
* Reduces concrete permeability
* Increases concrete strength
* Improves resistance to corrosion