Microsilica for fibre cement

What is Elkem Microsilica?

Elkem Microsilica consists of sub-micron, amorphous , non-porous spheres of silicon dioxide (silica, SiO2) and small agglomerates of these. The average particle size of the spheres is about 0.15 micron. Although some of the spheres exist as single entities, most of them form primary agglomerates with typical particle range 0.1 - 1 micron.

Microsilica also contains some larger, secondary agglomerates typically 5 - 50 micron. They are easily broken down to primary agglomerates when the microsilica is mixed with water.

Benefits of microsilica

• As an extremely reactive pozzolan, Elkem Microsilica forms additional binder and therefore strengthens the fibre cement product.
• As an ultrafine material, microsilica increases the packing density of the fibre cement matrix.
• The ultra-fine Elkem Microsilica particles form a more refined pore structure, with lower over-all porosity consisting of smaller pores, and thereby enhance the durability of the fibre cement product.
• In the fresh state, Elkem Microsilica aids in binding water and thereby enhances the plasticity of the fresh mix.
• Increases the bending strength of fibre reinforced cement
• Improves the freeze-thaw properties of fibre cement

Product grades

Microsilica is classifed according to different grades, which reflect the material analyses and properties.

For fibre cement Elkem recommends

• The powder grades 940, 
• The slurry grade Emsac 500 S

Grade 940 is available in undensified and densified forms, with bulk density 200-350 kg/m3 and 600-700 kg/m3.

Emsac 500 S is an aqueous suspension of Elkem Microsilica in water, 50% by weight of dry solids. The density of this slurry is 1400 kg/m3.

Supply and packaging

Elkem Microsilica can be delivered as dry powder or in wet form as slurry.

The dry powder can be delivered in a variety of packaging according to customer requirements. Elkem's standard 25 kg paper bag can be delivered shrinkwrapped on pallets or slip sheet.

Big bags can be delivered in different weights according to customer requirements. The bagged material can be transported in containers, on road carriers or shipped as break bulk from Elkem Microsilica sources from different parts of the world.

Elkem delivers dry material as well as slurry in road tankers to customer silos or tanks. Slurry can be delivered from plant tanks or from Elkem's distribution tanks throughout Europe