Microsilica
Beyond Group Global Suppliers Provide Microsilica, or silica fume, is a highly reactive material used in small quantities to enhance concrete properties. It is a byproduct of electric arc furnaces used in special metals production. Microsilica finds applications across various industries, including refractories, plastics, clay, electronic materials, adhesives, silicone rubber, and precision casting.
Microsilica (Silica Fume)
Microsilica, or silica fume, is a highly reactive material used in small quantities to enhance concrete properties. It is a byproduct of electric arc furnaces used in special metals production. Microsilica finds applications across various industries, including refractories, plastics, clay, electronic materials, adhesives, silicone rubber, and precision casting.
What is Silica Fume?
Silica fume, or microsilica, is an amorphous (non-crystalline) form of silicon dioxide. This extremely fine powder, collected as a byproduct of silicon and ferrosilicon alloy production, consists of spherical particles averaging 150 nm in diameter.
Advantages of Microsilica
- Reduces concrete permeability
- Enhances concrete durability
- Increases final strength
- Beneficial for high-resistance concrete applications
- Improves bond strength to steel
- Mitigates alkali-silica reaction
- Offers excellent resistance to sulfate or seawater attack
- Reduces steel corrosion
Forms of Microsilica
Microsilica is available in various forms for different applications:
- Non-dense Microsilica: With a volume density of about 200 kg/m³ to 300 kg/m³, it is challenging to use in the concrete industry.
- Dense Microsilica: This type has a higher volume density (more than 500 kg/m³), making it easier to use and cheaper to transport.
- Pelletized Microsilica: Pelletized into 0.7 to 1 mm diameter pellets with a bulk density greater than 600 kg/m³.
- Slurry Microsilica: Produced by mixing non-dense microsilica with water to achieve a specific density of 1400 kg/m³, leading to a more homogeneous concrete mixture.
Applications of Microsilica
Microsilica’s applications are diverse:
- Refractories: Used in casting, porous, and fused refractories, including low-cement refractory castings, prefabricated parts, and iron trenches.
- Mortar and Concrete: Ideal for port docks, tall buildings, railway bridges, reservoir dams, and concrete pavements.
- Protective Coatings: Employed as an active ingredient for fire protection, environmental protection, and anti-corrosion coatings.
- Wall and Decorative Materials: Utilized for thermal insulation mortar, polymer mortar, and as a bonding agent for wall insulation.
- Putty: Incorporated in putty powder for insulating external and internal walls.
- Filling and Strengthening: Used in resin, rubber, paint, and unsaturated polyester as a filling and strengthening material.
- Additives: These are commonly used as additives in various active areas.
Impact of Microsilica on Hardened Concrete
Microsilica significantly influences hardened concrete by:
- Increasing concrete and mortar strength
- Raising the elasticity coefficient
- Reducing concrete creep
- Lowering permeability
- Enhancing durability
Using Microsilica in Concrete
Several methods are employed to incorporate microsilica into concrete:
- Adding Dry Microsilica to Dry Concrete Materials: This method can cause issues like spreading in the air, poor mixing, and clumping. A strong mixer can help mitigate these problems.
- Adding Microsilica to Fresh Concrete in a Truck Mixer: Similar to the first method, this approach can result in uneven mixing and airborne dispersion.
- Mixing Microsilica with Part of the Concrete Water: Preparing a microsilica slurry and adding it to concrete ensures uniform distribution and minimizes health risks from airborne particles.
