Why do we use silica fume in concrete?
9 – Use of silica fume in concrete Condensed silica fume is a very fine, amorphous, and reactive mineral admixture. It reacts readily with the calcium hydroxide, which is produced during Portland cement hydration. Silica addition refines pore structure and produces concrete of improved mechanical strength.
Does fumed silica cause silicosis?
Occupational exposure to crystalline silica dust is associated with an increased risk for pulmonary diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and lung cancer.
How do you dispose of fumed silica?
Environmental Precautions: Fumed silica is a not hazardous waste. Dispose of in landfill in accordance with international, national, U.S. federal and local laws and regulations.
Can fumed silica cause silicosis?
No known health effects are found from exposure to crystalline silica at the levels normally found in the environment. small crystalline silica particles for a long time (typically years) can develop silicosis, a serious lung disease.
How does silica fume improve concrete strength?
A reduction in water-binder ratio (from 0.35 to 0.30) increased the ability of the concrete to resist chloride ion’s penetration. The introduction of silica fume in concrete reduced the water absorption capacity of concrete. A change in water-binder ratio also dramatically reduced the water absorption of concrete.
Is colloidal silica safe?
Colloidal silica is not classified as harmful, but as mildly irritating. Because the products can have a drying effect on the skin, protective gloves should always be used. In case of skin contact, wash the area of contact with plenty of water. The use of safety glasses is always recommended.
Does silica burn skin?
Main Routes of Exposure: Inhalation; skin contact; eye contact. Inhalation: At high concentrations: can irritate the nose and throat. Skin Contact: Not irritating.
Is fumed silica a combustible dust?
: None. : Warning. : May form combustible dust concentrations in air. : Keep away from all ignition sources including heat, sparks, and flame.
Does fumed silica expire?
Further, it is recommended that fumed silica packaged in paper bags be used within two years after manufacture date as bags may begin deteriorating beyond this time period.
What is silica fume made of?
Fumed silica require very strictly moisture-proof method: packaged in kraft paper and rounded by plastic layers. Silica fume, also known as microsilica, is a fine-grain, thin, and very high surface area silica. -Via wikipedia
What is precipitated silica and fumed silica?
Precipitated silica is a type of silica that is amorphous and appears as a white, powdery material. The key difference between fumed silica and precipitated silica is that fumed silica is usually small in size, whereas precipitated silica is usually larger in size.
Is silica filler the same as fumed silica?
Another question about silica filler is when is it best to use and when is another filler a better choice. Note that fumed silica, that is amorphous silica produced in the flame method from silica, is NOT the same as silica fume.
What is fumed silica and how is it used?
Fumed silica is considered a specialty product since it does not have widespread uses like precipitated silicas. With this being said, fumed silicas’ unique properties allow for many different applications. Many of which one cannot achieve with other materials!