As we know concrete plays a vital role in the construction industry due to its inherent properties. However, nowadays with the extensive use of pre-stressed concrete especially for the construction of sky-rocketing buildings demand concrete with higher compressive strength. Hence, the addition of some other materials is crucial for enhancing the strength of the concrete. At this juncture, the Microsilica also known as silica fumes proved worthy as it increases the strength of the material. Microsilica is a by-product of the industrial manufacture of ferrosilicon and metallic silicon in high-temperature electric arc furnaces. It is a mineral admixture made of very fine spherical silicon dioxide with an extremely high surface area. As a result of pozzolanic and cementitious properties of Silica fume, it can create an impact on the concrete behaviour in many ways, thus improving the qualities of concrete. As Microsilica is an essential element of modern refractory technology, it is very compatible with cements, and this quality, in turn, helps it to prevent the conversion of high-alumina cement. The desired characteristics of both pozzolanic materials combine in producing optimally durable concrete. Microsilica provides more uniform distribution and a greater volume of hydration products and decreases the average size of pores in the cement paste.
Features of Microsilica
- High Compressive strengthThis is a remarkable feature of Microsilica as it gives compressive strength to concrete.
- High strength and High-performance concrete is being widely used throughout the world. Adding the Microsilica in concrete can reduce the water binder ratio and increase the binder content which also gives impact resistance.
- Resistance against corrosion The permeability of microsilica offers protection against corrosion. Besides, Microsilica concrete has much higher electrical resistivity. Microsilica concrete is therefore suitable for structures exposed to saltwater, Harbour structures, ports, bridges, docks, etc.
- Chemical Resistance Microsilica concrete has a low penetrability and high chemical resistance that provides a higher degree of protection against chemicals resisting cement or other cementitious binder systems.
- Decreases Heat Another feature of Microsilica is heat reduction, as it performs well in thick sections. It is also the most effective way of achieving low heat without sacrificing early age strength. Besides it, the property of low permeability helps Microsilica as an integral waterproofer for below ground structures.
- Abrasion Resistance The Microsilica added concrete has very high abrasion resistance. Therefore it is quite used in floor and pavement construction.
Let’s find out how Microsilica works in Concrete…
As mentioned above Microsilica is noted for its Pozzolonic effect. When water is mixed with cement, hydration occurs forming two products as Calcium silicate hydrate and Calcium Hydroxide. And when the Microsilica is added to cement it will react and reduce rather the weak Calcium Hydroxide simultaneously providing the much desired binding strength. Another remarkable effect of Microsilica is the Micro filler effect, as Silica Fume is an extremely fine material, due to this, the addition of Microsilica can fill the water spaces in fresh concrete. Microsilica provides a more uniform distribution and a greater volume of hydration products; as filler, microsilica decreases the average size of pores in the cement paste. The addition of microsilica to a concrete mix alters the cement paste structure. Because the microsilica particles are so small they disperse among and separate the cement particles. The resulting fine, uniform matrix can give markedly higher compressive, flexural, and bond strength.Microsilica reduces the rate of carbonation, decreases permeability to chloride ions, imparts high electrical resistivity, and has little effect on oxygen transport. Therefore, microsilica concrete can be expected to be strongly protective of reinforcement and embedments. The silica fume reacts rapidly providing high early strength and durability.
Advantages of Microsilica
- Silica fume is known for good adsorption performance, and easy to mix, no agglomeration phenomenon.
- It can increase thermal conductivity thus eliminating stress and preventing cracks.
- Also can effectively reduce and eliminate precipitation and stratification.
- Early strength, microsilica concrete can shorten the induction period and have the characteristics of early strength.
- Microsilica is economical, it is cost-effective.