Silica Fume (Microsilica) is a mineral composed of ultra fine amorphous spheres of silicon dioxide(SiO2), Produced during the manufacture of silicon or ferrosilicon. Silica Fume (Microsilica) ’s appearance is grey black powder and average particle size is 0.15 micron in diameter.Specific surface area is ranging from 15,000 to 20,000 m2/kg,has dynamic surface activity. Silica Fume (Microsilica)’s bulk density is 150-300kg/M3 in natural(undensified)form. In order to transport easily, Bulk density can be increased to 600-700kg/m3 through densification process.
1. General usage of Silica Fume (Microsilica)
(1) In the application of high strength, high wear resistance, underwater cast anti - dispersion concrete, silica fume content should not be too low, usually accounted for 5% to 10% of the gel material.
(2) For applications of ordinary strength, impermeability, high durability or self-compacting concrete, it is advisable to use a low silica fume content of multi-component gel material, usually accounting for 2% to 5% of the gel material.
2. Benefits in high performance concrete.
Silica Fume (Microsilica) delivers increased toughness and resistance to abrasion,corrosion and chemicals. High bridge,Marine structures and bridge deck overlays are subject to constant deterioration caused by rebar corrosion,abrasion and chemical attack. Silica Fume (Microsilica) could protect concrete against deicing salts,seawater,road traffic and freeze cycles.
(1) Very low permeability to chloride and water intrusion.
(2) Extremely high electrical resistivity(20 to 100times greater than ordinary concrete
(3) increased abrasion resistance on decks, floors,highways etc.
(4) Superior resistance to chemical attack from chloride,acid,nitrates,and sulphates.
3. Benefits in High strength concrete.
Silica Fume (Microsilica) provides engineers with greater desin flexibility. Traditionally used in high rise buildings for the benefit of smaller columns(increasing the usable space). Also used in precast and prestressed girders allowing longer spans in structural bridge designs.
(1) Compressive strength up to 20,000psi(140Mpa)
(2) High modulus of elasticity exceeding 6 million psi(40,000Mpa)
(3) High flexural strengths(14Mpa@28days)for airport pavements
(4) High early strength for fast-track construction projects and precast application.
4. Benefit in shotcrete.
Silica Fume (Microsilica) in shotcrete delivers greater economy,timesaving and more efficient use of sprayed concrete.used in rock stabilization,mine tunnel linings and rehabilitation of deteriorating bridge and marine columns and piles. Greater bonding strength assures outstanding performance of both wet and dry process shotcreting with less rebond loss and thicker application with each pass of shotcrete nozzle.
(1) Reduction of rebound loss up to 50%
(2) Improving production efficiency,with one-pass application thickeness up to 30cm
(3) higher bonding strength
(4) high electrical resistivity and low permeability.
(5) high compressive and flexural strengths.
25kg/bag or 800kg/900kg/950kg/bulk bag and according to client request.
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