Three advantages of silica fume in concrete

In China, the output of silica fume is very low and the price is very high, about 5 times or more of the cement physique. Silica fume is generally used in the preparation of high strength concrete. Like viaducts, ports, skyscrapers, offshore platforms, dams, power stations, etc. So what are the advantages of using silica fume in concrete?

As we all know, silica fume has a small particle size and a large specific area, and has the characteristics of high sulfur purity and strong volcanic ash activity. Therefore, the addition of micro-silica powder as a blending agent has several properties in several aspects.

1. Improve the early strength and final strength of concrete

HHBache of Canada proposed that when silicon powder is used in combination with superplasticizer, the water-to-binder ratio (W/C+Si) of concrete can be reduced to 0.13~0.18, and the cement particles are filled with silicon powder and compacted. The compressive strength is 3 to 5 times that of the non-silicon doping mixture. At present, the United States, Denmark, Norway and other countries have used silicon powder as a blending agent to arrange concrete with a strength of up to 1100 kg / cm 2 , and the process is simple and economical, so it is widely used.

2. Improve the impermeability, chemical resistance and specific resistance of concrete

Since the incorporation of silicon powder improves the compactness of the concrete and greatly reduces the voids of the cement, the impermeability of the silica fume concrete is improved. Foreign studies have shown that when the substitution rate of silicon powder in concrete is 10~20, the impermeability and chemical corrosion resistance of concrete are obviously improved, and the corrosion resistance of steel bars is also improved. At this time, since the increase in the density and the increase in the sulfur content, the intrusion and corrosion of the acid ions are effectively prevented.

3. Increase the density

The incorporation of silicon powder into the concrete increases the silicon content of the reaction. Under the electron microscope, crystal growth occurs in the cement stone voids of the silica-doped concrete. In addition, the silicon powder particles are very fine and uniformly fill the concrete micropores.

Silica fume has an irreplaceable advantage in concrete, which makes it widely used in concrete applications worldwide.