micro silica in concrete

Micro silica can also be called silicon ash, it is the by-product collected when smelting ferro silicon and silicon metal, the particle size is 325mesh, generally it can be divided into micro silica in concrete and micro silica in refractory, the micro silica in refractory generally require the content of SiO2 more than 95%, and need the micro silica to have high flow, but for the micro silica in concrete, generally require the content of SiO2 more than 85%, it will do not require flow but require the activity.



The micro silica is amorphous spherical particles, the micro silica in concrete can improve the rheological properties of concrete, the average particle size of micro silica is relatively small with a good filling effect, it can fill the spacing between cement granule, and improve the intensity and wear-resistance of concrete, what is more, it can reinforced concrete’s frost resistance, impermeability, steel corrosion resistance and abrasion resistance.

1.Frost resistance, when the added amount of silica fume small the frost resistance of micro silica is almost the same with the general concrete, when the added amount is more than 15%, the frost resistance is poor, so the added amount of micro silica show less than 15%. 

2. Impermeability, the permeability of concrete in sea is the most important factor to determine the durability of concrete engineering, because of the particle size of micro silica is small, 20 to 100 times smaller than cement particles, so it can fill into the gap between the cement particles to make the concrete dense, at the same time, micro silica through the secondary hydration will produce a gel, it will block the percolation channel in concrete, the permeability of concrete increase with the increase of water-to-binder ratio.

3.Steel corrosion resistance, the high alkalinity of concrete provides the conditions for forming a passivation film for the steel bars in ordinary reinforced concrete. Once the passivation film is broken, the steel bars will undergo electrochemical corrosion, and the corrosion rate depends on the moisture and speed at which oxygen enters the concrete.So the micro silica in the concrete can improve the compactness and increase the electrical resisitivity. Therefore, the resistance to corrosion of steel bars is greatly improved, and the improvement of electrical resistivity increases with the increase of the content.

In general, the micro silica in the concrete can help it to appear better performance than before, Anyang Huatuo Metallurgy Co.,Ltd has in the micro silica for several years, if you have any confused, welcome for your consult.