Micro Silica is a shapeless polymorph of silica (SiO2 / silicon dioxide). It is also recognized as silica fume or condensed silica fume. It is an ultrafine powder supplied by the Micro Silica Exporters collected as a by-product throughout the production of the silicon and ferrosilicon alloys. It is uniquely pure and efficient. When used as an additive for concrete, micro silica melodramatically progresses the durability and shelf life of concrete, thus saving conservation costs. When added to the concrete mix, a small dose of micro silica presents millions of tiny silicon dioxide elements into the concrete. It seals the gaps in the wet concrete mixture and responds chemically with the Portland cement
Properties of Micro Silica Powder in India
- The diameter of a silica fume element ranges from 100 to 200nm.
- Its particles are spherical.
- The thickness of condensed silica fumes obligatory to be used as an additive in concrete must be about 500 to 700 kg/m3.
- It comprises 85 to 97% of silicon dioxide.
- The other elements present in micro silica are carbon, Sulphur along with the oxides of aluminum, iron, calcium, magnesium, sodium, and potassium.
- Substituting the cement with about 10% silica fumes consequently increases in compressive strength of the concrete.
- Strengthening corrosion is greatly reduced due to increased resistivity, high tensile strength, and less permeability.
Micro-silica provides a guard against the intrusion of chloride ions, thereby growing the time taken for the chloride ions to reach the steel bar and initiate corrosion. In addition, micro-silica concrete has much advanced electrical resistivity likened to OPC concrete thus slowing down the corrosion rate
Silica fume concrete has a little weakness for penetration by sulphate ions and a high chemical resistance that delivers a higher degree of protection against sulphates than low tricalcium aluminate (C3A) and other sulphate fighting cement or flies ash and other cementitious binder systems.
By substituting cement with condensed silica fume and detecting its efficiency factor, a lower maximum temperature rise and the temperature difference will take place for concrete with the same strength. The performance is improved in association with slag and fly ash blends in the case of thick sections. It is also proved to be the most operative way of attaining low-heat concrete without compromising its strength at an early age.
The abrasion resistance of Silica smoke concrete is very high. The use of silica fume solid in floor and pavement construction saves time and money. It also advances the working efficiency of the facility operator. The hydraulic abrasion-erosion resistance of concrete is greater, which makes it impeccably suitable for the construction of dam spillways.
Advantages of Micro Silica
When micro silica is added to ordinary cement, it improves the below-mentioned properties of concrete:
- Bond improvement
- Lesser heat of hydration
- Reduction of alkali-aggregate reaction
- Enhanced compressive strength
- Reduced permeability
- Minimizes the bleeding
- Reduces segregation of concrete
- Improves the durability of concrete
- Makes the concrete more cohesive