Brief introduction:

1. Basic Definition and Characteristics

Alternative names: Microsilica or Condensed Silica Fume

Essence: During the smelting of ferrosilicon/industrial silicon, SiO ₂ vapor in a high-temperature electric arc furnace is oxidized by oxygen and condensed to form ultrafine amorphous silica powder.

Key physical properties:

Particle size: 0.1-0.3 μ m (100 times finer than cement, specific surface area ≥ 15000 m ²/kg)

Form: Amorphous spherical particles (under electron microscope)

Composition: SiO ₂ ≥ 85% (up to 98%), containing a small amount of Fe ₂ O3, CaO, MgO, etc

Density: 2.2 g/cm ³ (loose packing density is only 200-300 kg/m ³, requiring densification treatment)

Activity: high pozzolanic activity (reacts with cement hydration product Ca (OH) ₂ to form C-S-H gel)

Features and usage

Cement or concrete admixture

Microsilicon powder can fill the pores between cement particles, and form gel with hydration products and gel with alkaline material magnesium oxide. In cement-based concrete, mortar and refractory castable, adding appropriate amount of silica fume can play the following roles:

1. Significantly improve the performance of compression resistance, folding resistance, permeability resistance, corrosion resistance, impact resistance and wear resistance.

2. With water retention, prevent segregation, bleeding, greatly reduce concrete pumping resistance role.

3. Significantly extend the service life of concrete. Especially in the chlorine pollution erosion, sulfate erosion, high humidity and other harsh environment, the durability of concrete can be doubled or even several times.

4. Significantly reduce the ground ash of shotcrete and castable, and improve the thickness of single spraying layer.

5. Is a necessary component of high strength concrete, has been C150 concrete engineering applications.

6. It has the effect of about 5 times cement, which can reduce the cost and improve the durability when used in ordinary concrete and low cement castable.

7. Effectively prevent concrete alkali aggregate reaction.

8. Improve the densification of pouring refractory. When co-existing with Al2O3, mullite phase is more likely to be formed, which enhances its high temperature strength and thermal vibration resistance. 9. Strong pozzolanic effect. When mixing concrete, secondary hydration reaction can occur with cement hydration product Ca(OH)2 to form cementitious products, fill the structure of cement stone, improve the microstructure of slurry, and improve the mechanical properties and durability of hardened body.

10. Microsilicon powder is amorphous spherical particles, which can improve the rheological properties of concrete.

11. The average particle size of micro-silicon powder is relatively small, which has a good filling effect and can be filled between the gaps of cement particles to improve the strength and durability of concrete.