Silica fume is a high performance mineral admixture of volcanic ash, mainly used to improve the strength and durability of concrete, and can replace silicate cement, is a good Concrete Admixture. By using silica fume, the performance of dry and wet shotcrete can be greatly improved, for example, in rock stabilization, tunnel lining and underground structure The application of the repair of underground structures, can obtain excellent performance.
The main performance of silica fume to improve the impermeability of shotcrete
- Silica fume particle size is small, the specific surface area is about 50 times that of conventional cement particles, with a strong microaggregate effect.
- The main component of silica fume is amorphous SiO2, high cementitious activity, can promote a large number of calcium alumina and other crystals generated, has a strong mineral filling effect.
- Silica fume can increase the cohesion of shotcrete, improve the fluid density in the jet process, and reduce the amount of gas wrapped in the fluid transfer process.
The effect of silica fume dosing on shotcrete
The amount of silica fume has always affected the performance of various materials, and the amount of silica fume in shotcrete also directly affects its seepage resistance, and even too large an amount may also affect the construction performance of shotcrete.
Favorable impact
Silica fume dosing in the range of 5% to 15%, shotcrete impermeability performance increases with the increase in the amount of silica fume, but when the dose reaches 9% or more, silica fume on the increase in the improvement of impermeability is significantly reduced: 9%, 10%, 15% of the amount of silica fume dosing, shotcrete flux reduction of 90%, 91% and 94%, respectively, the extreme difference is only 4%.
Adverse effects
As the dose of silica fume increases, the density of shotcrete will continue to increase, large dose of silica fume will also increase the flow resistance of shotcrete in the construction process and the probability of plugging, and the higher the dose, the more obvious; at the same time, the increase in the dose of silica fume will also reduce the crack resistance of shotcrete, increasing the chance of initial defect formation, but not conducive to improving the impermeability of shotcrete.
The density of silica fume on the impact of shotcrete
Usually, after the collection of silica fume, in order to facilitate transportation and use, more or less encrypted processing, but after research found that the degree of encryption of silica fume will also affect the shotcrete impermeability.
Silica fume according to the different degrees of encryption, divided into the Undensified Silica Fume, semi-dense silica fume and fully densified silica fume, with the degree of encryption degree of silica fume increasing, the greater the electric flux of shotcrete, the smaller the resistivity, the poorer the impermeability, which is due to the encryption of silica fume reduces its dispersion, and the same amount of silica fume dispersion, the better the improvement of the compactness of shotcrete, so in the use of silica fume to improve When using silica fume to improve the impermeability of shotcrete, silica fume products with a lower degree of encryption should be selected as far as possible.
Therefore, in order to reasonably improve the impermeability of shotcrete, we should choose the appropriate amount of silica fume and the degree of encryption.
HSA, as a famous silica fume and micro silica powder company in China, can provide high quality silica fume products for shotcrete, if you need, you can leave message on our website or send email to contact us.
