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Silica fume on the durability of concrete

From a comprehensive perspective, the effect of silica fume to improve the durability of concrete is the most significant, and can be used for almost any durability requirements of the environment. Impermeability, generally, the effect of silica fume increased impermeability is greater than the increase of strength,silicon powder mixed with a small dosage of low-strength concrete. 

The most common problem caused by the penetration of the environmental media of concrete durability. The concrete material itself, against a variety of media (water, oxygen, CO 2, C1 -, SO 4 -, etc.) the ability of permeability depends primarily on its internal pore structure (total porosity, pore size distribution) and the interfacial properties. The higher the harmful big hole total pore volume, the more adverse on confrontation medium permeability. For ordinary concrete, when the water-cement ratio is more than 0.6, the permeability of the concrete rapid growth, and for the concrete of the water-cement ratio less than 0.4, it can be considered to be substantially impermeable. For high-performance concrete mixed with a certain amount of silica fume, water cement ratio is typically less than 0.4 (minimal even only 0.18), and have ultrafine particles fill with. Therefore, the incorporation of high-performance silica fume concrete has very good anti- infiltration capacity. The ability to improve the resistance to chemical attack by adding silica fume can significantly reduce the permeability of the concrete and reduction of free Ca (OH) 2, which can improve the performance of concrete resistant to chemical attack.

Anti-alkali aggregate reaction, adding silica fume can improve the alkali-aggregate reaction in the concrete, since the silica fume particles improve the sealability of the cement bond material, reduce the speed of movement of the water through the slurry, so that an alkali expansion of the water required for the reaction reduced; also due to the reduction of alkali ions (Na + and K +) concentration of addition, the formation of the CSH fume have a lower calcium silicon ratio in the pore solution of the cement slurry can be increased crystal accommodate foreign ions (alkali molecules ) capacity, thereby reducing the risk of reduction into silicon and lime gel. The anti-reinforced corrosive, concrete Overbased to ordinary reinforced concrete reinforced to provide conditions for the formation of the passive film, once the passive film destruction, reinforced electrochemical corrosion occurs. The etching speed depends on the speed of moisture and oxygen get into the concrete.

Adding silica fume can improve the compactness of increased resistivity, so performance is greatly improved resistance to corrosion of steel bars, silica fume to improve the resistivity increases with increasing silica fume content. Abrasion resistance requirements of high-speed flow of hydraulic discharge structure surface protection material with high impact and abrasion resistance to cavitation. Add silica fume can improve the abrasion resistance of the concrete in the concrete. Add silica fume to improve the abrasion resistance of the concrete is due to the improvement of the abrasion resistance and hardness of the slurry itself, as well as to improve the adhesion of the grout aggregate interface, so that the coarse aggregate is difficult to be eroded by the abrasive action.

Silica fume anti-abrasive concrete compare to silica fume concrete, the general abrasion resistant ability can improve 1 time, the cavitation resistance capacity can be increased more than 3 times. Generally, the multiples of anti-cavitation ability is greater than the abrasion resistant ability multiples. With the silica fume content increased, fume erosion-resistant strength of the concrete also increased, and when fume dosage is more than 20%, its strength and resistance to abrasion properties began to decrease, according to concrete against abrasion the performance level requirements, generally from 8% to 10% is appropriate. Have a certain impact on the cement and aggregate species to improve resistance to abrasion. Studies by metal powder supplier found its ability to improve the anti-abrasion difference in the pure dam or portland cement preparation of silica fume anti abrasive concrete is worse than early-strength the P silicon and slag cement formulated silica fume concrete, of silica fume gravel concrete improved abrasion resistance ability higher than the silica fume pebble concreteFind Article, silica fume modified iron ore stone concrete resistance to abrasion than a 70% increase in river gravel.

Source:http://www.mhcmp.com

Article Tags: Silica Fume Concrete, Adding Silica Fume, Silica Fume, Fume Concrete, Adding Silica, Abrasion Resistance

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