company name: gansu lixinyuan microsilica co. ltd
contact person: manager sun
email address: [email protected]
address: no. 2599, yanbei road, chengguan district, lanzhou city, gansu province
the use of microsilica as a blending agent in the concrete industry is an area in which the use of silicon powder at home and abroad is early, most successful, and the most widely used. due to the fine particle size, large specific surface area and high pozzolanic activity, the micro-silica powder can be used as an additive to prepare high-strength concrete. since 1983, a large amount of silica fume concrete has been used in north america, europe, japan, etc. in 1989, there were 40,000 t of microsilica in norway for concrete, equivalent to 500,000 t of cement mixed with microsilica, canada. a total of 1 million m3 of microsilica concrete was used from 1985 to 1989. the addition of microsilica to concrete improves the multifaceted properties of concrete:
1 improve the early strength and final strength of concrete
foreign studies have shown that when the substitution rate of microsilica powder to cement is less than 30%, the steaming temperature is 80 °c, and the compressive strength of mortar is twice that of non-microsilica powder (100 mpa). , almost three times (150mpa). canadian studies have shown that when microsilica powder is used in combination with superplasticizer, the compressive strength of concrete is 3 to 5 times that of non-silicon doping. at present, the united states, denmark, norway and other countries have micro-silica powder as a blending agent to prepare concrete with a strength of up to 1100kg/cm2, and the process is simple. the effect of micro-silica powder in concrete increases with the amount of micro-silica powder, and the effect of activity and particles on concrete strength is gradually enhanced.
2 increase the density
the incorporation of micro-silica powder into the concrete increases the silicon content of the reaction. under the electron microscope, crystal growth occurs in the voids of the cement stone mixed with micro-silica powder concrete. in addition, the micro-silica powder particles are fine, uniformly filling the concrete micropores, reducing the micro-empty volume, thereby enhancing the compactness.
3 improve concrete segregation and bleeding performance
foreign studies have proved that the more the micro-silica powder is mixed, the more difficult it is for the concrete material to segregate and bleed. when the substitution rate reaches 15%, the concrete slump does not produce segregation and bleeding even if it reaches 15-20 cm, when the substitution rate when it reaches 20% to 30%, it is not easy to cause segregation when the concrete is directly placed in tap water.
4 improve the impermeability, chemical resistance and specific resistance of concrete
since the incorporation of micro-silica powder improves the compactness of concrete and greatly reduces the voids of cement stone, the impermeability of micro-silica fume concrete is improved. at home and abroad, it is considered that when the micro-silica powder substitution rate in concrete is 10%-20 when the concrete is impaired and chemically resistant, the corrosion resistance of the steel is also improved. this is due to the improvement of compactness and the increase of sio2 content, effectively preventing the intrusion and corrosion of acid ions. . in addition, due to the high specific resistance of micro-silica powder, the specific resistance of concrete can be increased by 1.9-16 times, which is beneficial to protect steel bars and embedded parts. at present, these technologies have been practically applied in projects such as port embankments, hydropower dykes, airport runways, cross-river tunnels, and anti-seepage and oil-resistant floors of multi-storey buildings, and special projects such as the yan'an middle road huangpu river cross-river tunnel in shanghai.