High-purity silicon powder manufacturers believe that silicon powder is a by-product of smelting ferrosilicon alloy or industrial silicon. It is obtained by oxidation and cold dust removal of silicon steam discharged from the flue. Silica fume is one of the best admixtures, and it is also an expensive admixture. Generally only used for high-strength and high-durability concrete.
Silicon powder is mainly supplied in two forms, namely original silicon powder and densified silicon powder.
1. Raw silicon powder, that is, the product collected directly by the dust collector, has a loose volume of about 150-200 kg/m3. Raw silicon powder is generally transported in bags. Due to low density and low long-distance transportation efficiency, manual bag breaking is often used to pour silica powder into the concrete mixer, resulting in heavy dust in the working environment and low work efficiency.
2. Densified silicon powder. High-purity silicon powder manufacturers believe that in order to solve the problem of original silicon powder being unsuitable for long-distance transportation and low efficiency, they have developed a “micro-silicon densification technology” that increases the bulk density of silicon powder. Using this technology, the original silicon powder is rolled into small particle balls under the action of compressed air flow, so that the loose volume of silicon powder is increased to 500-700 kg/m3. It is greatly convenient to use. The cohesive force of the small densified silicon powder particles is weak, and it is very easy to disperse during the mixing process in the concrete mixer. Therefore, the silicon powder particles can be put into the mixer after the aggregate is fed to ensure the dispersion of the densified micro silicon particle groups. properties and good dispersion.
For the mix proportion design of silica fume concrete, the mixing method of silica fume (silica fume), the amount of silica fume, the amount of water reducing agent and the adjustment of aggregates are mainly determined according to the design requirements. Others are based on ordinary concrete design methods. conduct.
Adding silica fume to concrete can increase the density of concrete, enhance its strength, and improve its impermeability and wear resistance. How to incorporate silica fume: There are two ways to use silica fume in concrete: one is internal mixing, the other is external mixing, and should be used in conjunction with water-reducing agents. In the internal mixing method, silica fume is commonly used to replace cement, which is divided into two types: equal replacement and partial equal replacement. Equivalent substitution means replacing the same amount of cement with the amount of silica fume, and partial substitution means replacing 1 to 3kg of cement with 1kg of silica fume. For research purposes, the general dosage is 5% ~ 30%, and the water-cement ratio generally remains unchanged. In the external admixture method, silica fume is mixed into concrete like an admixture, but the cement dosage is not reduced, and the dosage is generally 5% to 10%.
The use of silica fume concrete in water conservancy and hydropower projects can improve the wear resistance of the project. Traditional wear-resistant materials at home and abroad are mostly polymer materials such as epoxy mortar. Although this material has good wear resistance, its linear expansion coefficient is several times higher than that of ordinary foundation concrete. It is not suitable for the temperature of foundation concrete. It is easy to crack and fall off under natural climate conditions. The construction is complex, toxic, expensive, and cannot be widely used. use. However, when silica fume concrete is used, the wear resistance is increased by about 1 times, and the wear resistance at 48m/s flow rate is increased by more than 3 times.
