Silica fume is a by-product of smelting ferrosilicon alloy or industrial silicon, which is obtained by oxidation of silicon vapor discharged through the flue and cold dust collection. Silica fume is the best performance of all admixtures, but also the most expensive admixture. Generally only used in high-strength, high-durability concrete.
Advantages of silica fume in concrete:
1. Microsilica fume is a neutral inorganic filler with very stable physical and chemical properties. Does not contain crystal water, does not participate in the curing reaction, and does not affect the reaction mechanism.
2. It has good wettability to various resins, good adsorption performance, easy to mix, and no agglomeration.
3. Micro-silica fume has reasonable particle size distribution, strong compactness, high hardness and good wear resistance, which can greatly improve the tensile, compression, impact strength and wear resistance of cured products, and the wear resistance can be increased by 0.5-2.5 times .
4. It can increase the thermal conductivity, change the adhesion, and increase the flame retardant performance.
5. It can reduce the exothermic peak temperature of the curing reaction of epoxy resin, reduce the linear expansion coefficient of the cured product and the shrinkage rate of the cured product, thereby eliminating internal stress and preventing cracking.
6. Due to the fine particle size and reasonable distribution of silica fume, it can effectively reduce and eliminate precipitation and stratification.
7. The quality of silicon micropowder is pure, the content of impurities is low, and the physical and chemical properties are stable, so that the cured product has good insulation performance and arc resistance.
8. The chemical composition of micro silica fume is silicon dioxide (SiO2), which is an inert substance. It does not chemically react with most acids and bases. The silicon powder is evenly distributed and covers the surface of the object. It has strong corrosion resistance and anti-corrosion ability. The cavitation ability is increased by 3-16 times.
9. Micro silica fume, small bulk density: one is between 0.2-0.8, and the other is between 1.0-2.2. As a polymer filling material, it uses less than other mineral fillers, and the filling weight is small, which saves the amount of polymer used, so it can reduce product costs.
10. Frost resistance: After 300-500 rapid freeze-thaw cycles, the relative elastic modulus of silica fume will decrease by 10-20%, while the relative elastic modulus of ordinary concrete will increase by 30-30% after 25-50 cycles. 73. %. Therefore, the frost resistance of concrete can be improved.
11. Early strength: Silica fume concrete shortens the induction period and has the characteristics of early strength. These functions are all good.