Micro-silica fume powder, also called silica fume or cohesive silica fume, is produced by ferroalloys in smelting ferrosilicon and industrial silicon, and a large amount of highly volatile SiO2 and Si gas is produced in the mineral-heated electric furnace, and the gas is discharged and rapidly oxidized with air to condense and precipitate. It is a by-product in large industrial smelting, and the whole process needs to be recovered with dust removal and environmental protection equipment, and because of the small density, it also needs to be encrypted with encryption equipment.
Adding 5-10% micro silica powder to cement products can enhance the strength and compactness of concrete. When producing cement products with corresponding strength standards, it can reduce the cost of cement materials and improve the performance of products. Micro silica powder can fill the pores between cement particles, while generating gel with hydration products and reacting with alkaline material magnesium oxide to generate gel.
In cement-based concrete, mortar and refractory casting materials, mixing the right amount of silica fume can play the following roles:
1. Significantly improve the compressive, folding, seepage resistance, anti-corrosion, impact resistance and wear resistance.
2. It has the function of water retention, preventing segregation and water secretion, and significantly reducing the pumping resistance of concrete.
3. Significantly prolong the service life of concrete. Especially in harsh environments such as chlorine salt pollution erosion, sulfate erosion and high humidity, it can double or even multiply the durability of concrete.
4. Significantly reduce the landing ash of sprayed concrete and casting material, and increase the thickness of single spray layer.
5. It is a necessary ingredient of high-strength concrete, and there are already engineering applications of C150 concrete.
6. It has about 5 times the effect of cement, and can be used in ordinary concrete and low-cement castables to reduce costs. Improve durability.
7. Effectively prevent the occurrence of concrete alkali aggregate reaction.
8. Improve the denseness of castable refractory materials. When co-existing with Al2O3, it is easier to generate mullite phase, which makes its high temperature strength and heat vibration resistance enhanced.
9. With strong volcanic ash effect, when mixing concrete, it can have secondary hydration reaction with cement hydration product Ca(OH)2, forming cementitious products, filling cementite structure, improving the microstructure of slurry, and improving the mechanical properties and durability of hardened body.
10. Micro-silica powder is amorphous spherical particles, which can improve the rheological properties of concrete.
11. The average particle size of microsilica powder is relatively small, which has good filling effect and can fill in the gap between cement particles to improve the strength and durability of concrete.
12. The particle size of micro-silica powder is 100 times smaller than that of cement particles, filling in between the gaps of cement particles, which has the same effect as cement particles filling in between the aggregates, increasing the denseness of concrete.
