Microsilica Powder (Silica Fume)
MIP440
Nano Powder from Ferrosilicon Production Process
Enhancement of Concrete Quality Properties
Silica Fume Description
One of the main reasons for concrete permeability is the micro and fine pores between the aggregates, which are created due to a lack of fillers and fine particles. Another cause of permeability is the formation of capillary tubes after water evaporation during the hydration process. Silica fume or microsilica powder is an ideal additive for filling these voids. The particles of silica fume are much finer than cement particles, allowing them to fill the very fine microscopic spaces. Microsilica powder is a gray powder consisting of approximately 94-96% silicon dioxide (SiO2) that is obtained from the ferrosilicon production process in electric arc furnaces. It is added to concrete during production to enhance certain properties, leading to a denser cement paste structure, reduced permeability, and increased strength. The use of this product also improves concrete’s abrasion resistance, durability, and longevity.
Microsilica powder, also known as silica fume, is a very fine powder. Due to its pozzolanic properties, it is used as an additive in concrete to increase strength and durability. This additive offers high resistance to moisture and also has a low thermal expansion coefficient.
Mechanism of Action of Silica Fume
When silica fume is added to the concrete mix, the active SiO2 in the silica fume reacts with the free calcium hydroxide (Ca(OH)2) present in the micropores of the concrete. This forms insoluble calcium silicate crystals, resulting in an increase in concrete density, reduced permeability, and enhanced properties.
Properties and Effects of Silica Fume
- Increased compressive, tensile, and flexural strength of concrete
- Enhanced electrical properties of concrete
- Prevention of cancerous phenomena
- Prevention of rebar corrosion
- Increased abrasion resistance of concrete
- Improved durability and longevity of concrete
- Reduction of the potential for alkali-aggregate reactions
- Protection of concrete against chemical attacks
- Higher concrete density
- Improved workability and ease of concrete placement
- Enhanced cohesion and reduced permeability
- Reduced cement consumption
Applications of Silica Fume
- Production of high-strength concrete with superior mechanical properties
- Manufacture of high-compressive strength concrete
- Suitable for producing dense and impermeable concrete
- Ideal for foundation and bridge deck concrete
- Suitable for use in all structural elements
- Can be used in tunnel concrete pouring and water transfer systems
- Ideal for all water-related structures such as pools, reservoirs, treatment plants, etc.
Physical and Chemical Specifications Table
| Property | Value |
| State | Pozzolanic powder |
| Color | Light or dark gray |
| Specific Gravity | 3.0 g/cm³ |
| Standard | SSIRI 13278 – ASTM C1240 |
| Particle Shape | Spherical and non-crystalline |
ASTM Standard: ASTM C1240 – SSIRI 13278
Silica Fume Consumption Rate
The recommended consumption of microsilica powder depends on the desired concrete properties, ranging from 7 to 12 percent of the cement weight. It should be noted that the addition of silica fume allows a reduction in cement consumption. Due to its fine particle size and ease of dispersion, silica fume should not be added alone. Because of its water-absorbing properties, it is best used with concrete superplasticizers to prevent cracking, reduce workability loss, and avoid lack of compaction.
Methods for Using Silica Fume
There are three main ways to incorporate microsilica into the mix:
- Silica fume can be added to the dry components during concrete mixing.
- It can be combined with a portion of the mixing water to form a slurry and then added to the mix.
- The best method is to combine silica fume with a portion of the mixing water and a specified amount of superplasticizer, mix it with a high-speed mixer to fully disperse, and then add it to the concrete.
Safety of Silica Fume
Silica fume is not considered toxic or environmentally hazardous.
- Always use a proper work mask to prevent inhalation of silica fume particles.
- If accidental inhalation occurs, drink a large amount of milk.
Silica Fume Storage
- Shelf Life: 3 years in its original packaging
- Storage Conditions: Keep away from cold, freezing temperatures, heat, and prolonged direct sunlight exposure.
- Ideal Storage Temperature: 10+ to 30+ degrees Celsius
Silica Fume Packaging
- Packaging: 20 to 40 kg bags
- Bulk Packaging: 300 to 500 kg drums
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