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CoGripedia your encyclopedia of terms used in the industrial flooring industry.

Silica Fume (SF) 


Silica fume can be added to a cement mixture to create very high strength concretes.

Technical Information

Silica Fume typically replaces around 10% of the Portland cement in a concrete mix and is a by-product of producing silicon alloys.

Concretes containing silica fume have the following properties compared to concretes containing 100% Portland cement:

  • Increased water demand due to the greater surface area from the spherical particles.  Concrete mixes containing silica fume generally require a high range water reducing admixture.
  • Increased short term and long term strength can be achieved.
  • Decreased workability for same water / cement ratio – it is rarely used without the addition of a superplasticiser to increase the workability to a normal level.
  • Reduced segregation and bleeding.
  • Decreased porosity – this leads to improved durability and increased resistance to corrosion of the reinforcement due to the low chloride diffusivity.
  • Can lower the chance of a damaging alkali-silica reaction and helps reduce or even prevent sulphate attack.

Even though silica fume is a waste product, it is still more expensive than Portland cement, as its strengthening qualities are in such high demand. For this reason, silica fume is usually only used in structures where a very high performance concrete is required.

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