A Microsilica admixture for ultra-high performing concrete.

What is Microsilica?

Also known as Silica fume, Microsilica is a mineral admixture composed of very fine solid glassy spheres of silicon dioxide. A by-product of the industrial manufacture of ferrosilicon and metallic silicon in high-temperature arc furnaces, Microsilica dramatically improves the strength, durability and impermeability of concrete.

Sika Fume microsilica admixture

How Microsilica works

Step 1: Pozzolanic action

A chemical reaction between the free lime Calcium hydroxide – Ca(OH) – in the cement paste and the silica fume particles, which results in the formation of an additional CSH (calcium silicate hydrate) gel.

This is the glue that holds the concrete constituents together and its formation increases the concrete’s compressive and flexural strength.

Step 2: Void reduction

Silica fume particles have a diameter of less than 1μm (1 micron = 0.00004 inch); about 100 times smaller than the average cement particle.

These fine particles fill the tiny voids and capillary pores within the cement matrix, significantly reducing porosity to produce an extremely dense and impermeable concrete.

The advantages of Microsilica

Aiding with corrosion and sulphate resistance, heat retention, waterproofing and abrasion, SikaFume-50 S is also a good choice for industrial and agricultural structures that are usually exposed to a wide range of chemicals due to its impenetrability.

In addition, Microsilica concrete has a much higher electrical resistance when compared to Portland Cement, which helps slow down the corrosion rate too.


Designed for environments where performance demands are high, SikaFume® -50S is available in slurry format and can be utilised in all forms of construction, including:

  • High-rise residential projects
  • Transport infrastructure
  • Coastal protection barriers and general marine environments
  • Power plants
  • Multi-storey commercial buildings
  • Material recycling plants