SILICA FUME IN CONCRETE

The American Concrete Institute (ACI) defines silica fume as “very fine non-crystalline silica produced in electric arc furnaces as a by-product ofthe productions of elemental silicon or alloys containing silicon”  (ACI 116R).  It is usually a gray colored powder, somewhat similar to portland cement or some fly ashes.  Silica fume is usually categorized as a supplementary cementitious material.  This term refers to materials that are used in concrete in addition to portland cement.

 Silica fume is frequently referred to by other names :

1. Condensed silica fume

2. Microsilica

 3.Volatilized silica

Silica fume is a by-product of producing silicon metal or ferrosilicon alloys in smelters using electric arc furnaces.  These metals are used in many industrial applications to include aluminum and steel production, computer chip fabrication, and productions of silicones, which are widely used in lubricants and sealants.  While these are very valuable materials, the by-product silica fume is of more importance to the concrete industry.  

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