Micro-silica fume can fill the pores between cement particles, and at the same time form a gel with the hydration product, and react with the alkaline material magnesium oxide to form a gel. In the cement-based concrete, mortar and refractory castables, mixing an appropriate amount of micro-silica fume can play the following roles:

1. Significantly improve the compressive, flexural, impermeable, anti-corrosion, impact and wear resistance properties.

2. It has the functions of retaining water, preventing segregation and bleeding, and greatly reducing the resistance of concrete pumping.

3. Significantly prolong the service life of concrete. Especially in harsh environments such as chloride pollution erosion, sulfate erosion, and high humidity, the durability of concrete can be doubled or even several times higher.

4. Significantly reduce the floor ash of sprayed concrete and castables, and increase the thickness of a single sprayed layer.

5. It is a necessary component of high-strength concrete, and C150 concrete has been applied in engineering.

6. It has about 5 times the effect of cement, and it can be used in ordinary concrete and low-cement castables to reduce costs and improve durability.

7. Effectively prevent the occurrence of concrete alkali aggregate reaction.

8. Improve the compactness of castable refractories. When coexisting with Al2O3, it is easier to form mullite phase, which increases its high-temperature strength and thermal shock resistance.