Silica Fume


Silica fume is a by product of producing silicon metal and other ferrosilicon alloys. These products are produced in an electric furnace and the smoke generated from the furnace is collected and known as silica fume or microsilica. This also helps reduce the carbon emissions of the producer.

Silica fume is made up of ultrafine particles with an average diameter of 150nm.


Silica fume consists primarily of amorphous (non-crystalline) silicon dioxide. Due to its fine particles, large surface area, and the high silicon dioxode content, silica fume is a very reactive "pozzolan" (forms cementitious properties when mixed with water and calcium hydroxide) when used in concrete.


The most common use of silica fume is in the production of concrete in which its compressive strength, bond strength and abrasive resistance improve the properties of the concrete. As the particle sizes are 1/100th the size of a normal cement particle, the compressive strength of the cement is increased resulting in high-strength concrete capable of a compressive strength of over 15,000psi - useful in supporting high rise building structures.

It is also used widely in the monolithic refactory industry.

Chemical Analysis

Standard Material % %
SF90 Grade SF92 Grade
SiO2 90% min 92% min
Al2O3 1% max 1% max
Fe2O3 2% max 2% max
CaO 3% max 3% max
MgO 3% max 3% max
C 3% max 3% max
Na2O 3% max 3% max
K2O 3% max 3% max
Moisture content @ 105C 1.5% max Not specified
Loss on ignition @ 950C 6% max 6% max
Grit size: >45 Micron 5% <45 Micron 90%
Bulk density: (densified) 600-750kg/m3 500-700kg/m3
Bulk density: (undensified) 280-350kg/m3 250-400kg/m3
Standard Material % %
SF95 Grade SF95 White Grade
SiO2 95% min 95% min
Al2O3 1% max 1% max
Fe2O3 1% max 0.8% max
CaO 1% max 1% max (inc Mg0)
MgO 1% max 1% max (inc CaO)
C 1.5% max 0.2% max
Na2O 1% max 0.8% max (inc K20)
K2O 1.2% max 0.8% max (inc Na2O)
Moisture content @ 105C 1.5% max Not specified
Loss on ignition @ 950C 2.4% max Not specified
Grit size: >45 Micron 5% Not specified
Bulk density: (densified) 450-700kg/m3 Not available
Bulk density: (undensified) 280-350kg/m3 300-450kg/m3


  • 25kg bags on pallets
  • 1mt big bags

We now supply pure white undensified silica fume which is a co-product from fused Zirconia production.