Microsilica 600

Microsilica 600 is a highly reactive pozzolan and falls into the amorphous silica family of products but has significant advantages over silica fume.

Materials with pozzolanic properties such as Microsilica 600 contain reactive silica and alumina that will, in the presence of water and free lime, react to produce cementitious compounds.

In addition to the pozzolanic properties there are two additional mechanisms that improve performance. Firstly, the fine graded particles of are able to fill the microscopic voids between the cement particles, improving “packing” and creating a less permeable concrete microstructure.

Secondly, the fine particle size reduces concrete bleed and helps reduce the interface layer between aggregate and cement paste. This reduces a weak permeable layer improving strength and durability. 

The Geosilica deposits in Rotorua indicate their age to be between 60,000-220,000 years. A selective quarrying operation ensures that the variation in chemical composition of Microsilica 600 is kept within strict limits. The process is then controlled to produce a powder with consistent defined particle size and maintain chemistry.


Microsilica 600 meets the requirements detailed in AS/NZS3582.3. Microsilica 600 can be used to enhance a number of hardened concrete properties and is used to develop concretes that provide significant improvement in durability or strength.


The benefits include: 

  • Very low chloride ion diffusion
  • Increased compressive strength
  • Reduced water permeability
  • Improved sulphate resistance
  • Improved abrasion resistance
  • Improved resistance to chemical attack
  • Improved stability in geothermal environments
  • Reduced efflorescence


The inclusion of 8% Microsilica 600 in combination with necessary minimum binder content and maximum water/cement ratios will meet the durability requirements for concrete detailed in the durability section of NZS3101 for marine and chemical attack applications.



Microsilica 600 is available in multi-walled paper sacks and in bulk.

Bag Sizes





Bulk Bag


Microsilica 600


x   x x


Typical Properties



Microsilica 600

Relative Density



Bulk Density - Aerated



Bulk Density - Non Aerated



SiO2 Content



SiO2 + Al203 Content



Relative Strength



Passing 2 micron