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Concrete Admixtures

Silica Fume (Microsilica)

Silica Fume (Microsilica), also known as silica fume, is formed by oxidation at high temperature. The particles are very fine, the shape of the glass sphere under the microscope, non-crystalline, amorphous, with excellent physical and chemical properties. Then the Silica Fume (Microsilica) can be fully dispersed and enriched into the gaps of cement particles after being added to the concrete, making the concrete more compact, especially for the calcium chloride dihydrate after cement hydration, which has a great absorption power, which can form silicon Calcium acid gel greatly improves the characteristics of concrete, thus solving the difficult problems of concrete density, strength, abrasion resistance, and frost resistance.

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. Therefore, Silica Fume (Microsilica) is mostly used as fillers and modified additives.

♦ Used for high-performance concrete, improve concrete strength, improve performance, and extend concrete life
♦ Used for refractory materials, enhance fluidity, reduce water consumption, and improve product strength and durability
♦ Used for dry mortar and grouting to improve early strength
♦ Used for wear-resistant floor, increase fluidity and improve wear resistance
♦ Used in paint, coating, resin, rubber and other polymer material filler

How to buy Silica Fume (Microsilica)?

 

 

-Special silica fume for high-speed rail ballastless track slab admixture
Sieving and rigorous inspection process and the production of special silica fume, may be used as dedicated passenger high non -ballasted track plate admixture, in China has been applied to a lot of high-speed non- ballasted track plate production.

-Water conservancy and hydropower engineering
Dam intake gates, diversion channels, tunnels, surge tanks, the lower structure of the main powerhouse (especially the turbine volute) and other hydraulic structures, make full use of silica fume concrete, which has good waterproof, impermeability, erosion resistance and resistance The characteristics of cavitation. At present, Silica Fume (Microsilica) concrete is widely used in China's Ertan Power Station, Zipingpu Water Control Project, and Yellow River Xiaolangdi Water Control Project, and has achieved good results, and has passed the test of several flood seasons.

-Industrial and civil construction projects
Silica Fume (Microsilica) concrete has the characteristics of early strength and high strength, and is widely used in industrial plants and high-rise buildings. It can increase the strength, reduce the section size of the component, shorten the construction period, and save the project cost.

-Traffic highway pavement engineering
The application of Silica Fume (Microsilica) on the pavement has strong wear resistance. It takes 28 days to pour the road with ordinary concrete to open to traffic. Generally, it takes 3 days to open to traffic for early-strength concrete. Damage to the concrete road surface is inevitable. Repairing with conventional methods will often cause traffic interruption, which will cause serious economic losses. The use of Silica Fume (Microsilica) concrete with early strength and wear resistance properties has an ideal effect after practical use. The runway of the airport requires the use of concrete of more than 80MPa and good wear resistance. Silica Fume (Microsilica) can also show their talents.

-Ports, bridges, salt water projects
The Silica Fume (Microsilica) concrete has high density and high resistivity, is not easy to form electrochemical damage, and enhances the corrosion resistance. In China, Hong Kong Qingma Bridge, Lianyungang Timber Wharf in Jiangsu, and Chongqing Dafosi Yangtze River Bridge are examples of successful applications.

-Shotcrete project
After adding Silica Fume (Microsilica) into the concrete, the adhesion performance and cohesiveness of the plastic concrete are significantly improved, the rebound amount is greatly reduced, the thickness of the shotcrete is increased at one time, the construction period is shortened, and the project cost is saved. In European and American countries, 75% of shotcrete is mixed with silica fume, while in Norway and Sweden, micro silica fume is an essential material for shotcrete.

Specification (Densified silica fume/Densified microsilica)

ITEMS

90D

92D

94D

96D

SiO2%

90.0min

92.0min

94.0min

96.0min

CL%

0.1max

0.1max

0.1max

0.1max

Fe2O3%

1.0max

1.0max

0.5max

0.2max

Al2O3 %

1.0max

1.0max

0.8max

0.5max

MgO %

1.5max

1.2max

1.0max

0.5max

K2O%

1.5max

1.2max

1.0max

0.7max

Moisture %

3.0max

3.0max

1.0max

1.0max

Loss on igntion %

6.0max

5.0max

3.0max

1.5max

Residue on 45um sieve

8max

5max

3max

3max

Specific surface(m2/gram)

18min

18min

20min

20min

Application

Why use Silica Fume (Microsilica)?

- 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.

- Benefits in high performance concrete.

Currently, in order to improve strength and increase durability, to add high-performance silica fume concrete used in the construction of infrastructure in the country has been widely accepted. High-performance concrete with Silica Fume (Microsilica) exhibits strong toughness, high frost resistance, abrasion resistance and chemical corrosion resistance, which prolongs the service life of the building and greatly saves the maintenance and repair costs in the later period. Bridges, piers collapses destroyed mostly due to its reinforced concrete is caused by severe water erosion, plus nuanced silica fume can be a good solution to this problem.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.

- 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.If Silica Fume (Microsilica) is added to high-strength concrete, the designer and constructor of the project can have more creative choices. For example, the use of high-strength concrete with Silica Fume (Microsilica) can avoid too many pillars in the design of super high-rise buildings to increase the use space of the building, and the addition of Silica Fume (Microsilica) can prefabricate prestressed beams with a larger span.
(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.

- 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. Plus nuanced Silica Fume (Microsilica) shotcrete used for rock solid engineering, mining tunnel lining, marine projects uprights or purchased hunger repair, good adhesion, not only in the construction dry and wet environment, reduced recoil, and fineness Suitable for various nozzles, making sprayed concrete construction more economical, time-saving and more effective.
(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.

- Application of Silica Fume (Microsilica) in refractory industry
Silica fume as a new raw material, refractory material commonly used in the industry. It plays an important role in the improvement of monolithic refractory materials, which is shown as:
(1) There are many pores in traditional refractory materials, and micro-silica powder is filled in the pores, which increases the volume density and reduces the porosity, and the strength can be significantly enhanced
(2) Silicon fume has strong activity and can form colloidal particles in water. Adding an appropriate amount of dispersant can enhance fluidity and improve casting performance
(3) Silica Fume (Microsilica) is easy to form in water—Si-OH group, which has strong hydrophilicity and activity, can enhance the agglomeration of refractory materials, at the same time, it can greatly improve the high temperature performance and extend the service life of refractory products
(4) Replace pure aluminum oxide mud as refractory material, saving cost

- Application of Silica Fume (Microsilica) in other areas

(1) Applied to cement industry This is similar to the concrete additive material. At present, some countries are continuously developing the application in this area and developing various mixed cements with better quality than ordinary cement.
(2) As anti-caking agent for fertilizer
(3) As raw material for silicate brick
(4) Using silica dust to prepare polymer products based on resins and other high molecular organic compounds, and use them as substitutes for black, white carbon black, talc, asbestos, aerosols, etc., as additives.

How about Silica Fume (Microsilica) and pozzolans?

With the development of social economy, modern buildings have higher and higher requirements for the quality of the construction side. Concrete is mainly used in various fields such as buildings, bridges, railways, oil fields, and roads in modern society. In these fields, the density of concrete, Strength, abrasion resistance, frost resistance and economic efficiency requirements are very high. In addition, the production of cement is a huge energy-intensive process, and the carbon dioxide emissions generated during the production process account for about 5% of the global man-made carbon dioxide emissions, so scientists have been looking for more environmentally friendly methods. Now a research team at the Massachusetts Institute of Technology has discovered that crushing volcanic ash and adding it to the mixture not only makes the process more environmentally friendly, but the resulting structure is also stronger.

Researchers from the Massachusetts Institute of Technology said that the cement produced by this formula has many advantages. Volcanic ash exists widely around both active and non-active volcanoes, and scientists have not yet found any practical uses for it. When it is combined with water and other materials to make a cement-like paste, it has convenient natural properties. While exploring the potential of this new additive, the research team led by Chin began to study the existing data on the "implied energy" of different industrial processes involved in the cement production process. This refers to the total energy used to crush rocks, solidify cement, or make concrete. Using these data, the team calculated the total energy of cement formulations containing different proportions of pozzolan, ranging from 10% to 50%. Then they produce some samples in the laboratory.

The researchers found that replacing 50% of traditional cement with pozzolan, with a particle size of 17 microns, reduces the embodied energy of the resulting concrete by 16%, although this hinders the overall strength of the material. Reducing the pozzolan particles to around 6 microns in size greatly increases its strength by creating more surface area for water and cement to bond together. On the basis of their earlier work, the scientists calculated how to change this embodied energy with varying proportions of volcanic ash. They found that 30% was the best ratio they had set, and they thought it would greatly reduce the embodied energy.

The Silica Fume (Microsilica) just has the two characteristics required for the above research: pozzolan activity and microparticles. In cement products and concrete admixtures , adding appropriate amount of Silica Fume (Microsilica), the Silica Fume (Microsilica) will fully expand, fill the gaps between cement particles, and at the same time generate calcium silicate colloid with water compounds, and alkaline material magnesium oxide It reacts to form magnesium silicate colloid , which significantly improves the compressive, flexural, impermeable, anti-corrosion, impact and wear resistance properties at various stages, significantly prolongs the service life, and significantly improves the product strength. Filling the concrete mixture with Silica Fume (Microsilica) will have the following effects.

(1) Improve concrete performance
Silica Fume (Microsilica) may be the concrete compressive strength, flexural strength increased significantly, incorporating 5-10% of silica fume, the compressive strength can be increased 10-30%, flexural strength increased by 10%. Impermeability is increased by 5-18 times. The Silica Fume (Microsilica) concrete shortens the induction period and has the characteristics of early strength. Silica fume concrete than ordinary concrete impact mill capacity increase 0.5-2.5 times, anti-cavitation ability to increase 3-16 times.

(2) Chemical resistance
Incorporating Silica Fume (Microsilica) into concrete can reduce the content of Ca (OH) 2 and enhance the compactness of concrete, which is beneficial to reduce the corrosion of weak acids. Because the CSH in concrete will differentiate in strong acid or high-depth weak acid, it is There is no such effect in high-deep weak acids. In addition, it can resist salt corrosion, and its anti-corrosion effect on chloride and sulfate is particularly obvious. The reason why it can resist acid corrosion is mainly due to the denser silica fume concrete and the improved pore layout, which reduces the transmission speed of harmful ions and reduces the soluble Ca (OH) 2 and ettringite (3CaO·Al2O3· 3CaSO4 ·32H2), so that the effect of hydrated calcium silicate crystals is better.

(3) Impermeability
Because the Silica Fume (Microsilica) particles are relatively small, 20-100 times smaller than the cement particles , it can fill the voids in the center of the cement particles to make the concrete denser, thus achieving the secondary hydration effect of the Silica Fume (Microsilica). However, the impermeability of silica fume concrete becomes stronger because new products block the penetration channels in the concrete. The permeability of concrete increases with the increase of water-binder ratio. This is because the compactness of water ash is relatively worse than that of concrete.

Package

25kg/bag or 800kg/900kg/950kg/bulk bag and according to client request.

MATERIAL SAFETY DATA SHEET (PDF version)Download

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