Silica fume concrete is composed of cement, silica fume, fine aggregate, coarse aggregate, and water. Fresh and hardened properties of silica fume concrete is superior to conventional concrete. For instance, it has higher compressive and flexural strength.
The durability of this type of concrete is superior to conventional concrete. Resistance against freezing and thawing and chemical attacks is better than concrete without silica fume. Segregation and bleeding is low in silica fume concrete, and the mixture is adhesive compared to traditional concrete.
The applications of the silica fume concrete in construction are seen in high-rise buildings, parking structure, dam structure, nuclear waste storage facility, and shotcrete rehabilitation.
Chemical Composition of Silica Fume Material
- It contains more than 90 percent of silicon dioxide.
- Other constituents are carbon, sulfur, oxides of aluminum, iron, calcium, magnesium, sodium, and potassium.
Physical Properties of Silica Fume Material
- The diameter of the silica fume particle ranges from 0.1 micron to 0.2 micron.
- The surface area is about 30,000 m²/kg.
- Density varies from 150 to 700 kg/m³ but when it is about 550 kg/m³, it is best suited as a concrete additive.
Properties of Fresh Silica Fume Concrete
- Silica fume concrete requires higher water content, for the same workability as of conventional concrete.
- Low workability
- Low slump value
- Possibility of bleeding and segregation is low
- The mixture is cohesive
- High plastic shrinkage
Properties of Hardened Silica Fume Concrete
- The compressive strength of silica fume concrete is higher than ordinary concrete (62 – 80 MPa), Fig. 1. Similarly, the flexural strength is also higher, Fig. 2.
- The modulus of elasticity is substantially higher than that of ordinary concrete.
- Creep of silica fume concrete is lesser than conventional concrete
Durability
- Permeability of silica fume concrete is low; hence, penetration of sulfate ions is low.
- Abrasion resistance and corrosion resistance are high.
- The reaction of silica fume with lime in the paste matrix improves durability. Lime material reacts with different chemicals and cause expansion.
Advantages
- Silica fume enhances the properties of fresh and hardened concrete.
- Silica fume reduces segregation and bleeding.
- High durability
- The finishing process is efficient due to low bleeding.
- High early compressive strength
- High flexural strength and modulus of elasticity
- High bond strength
- Suitable for mass concreting since it prevents thermally induced cracking.
Disadvantages
- Availability issue
- High cost
Applications
- High rise buildings, Fig. 2.
- Parking structure, Fig. 3.
- Dam structure, Fig. 4.
- Nuclear waste storage facility
- Shotcrete rehabilitation
FAQs on Silica Fume Concrete
What is silica fume concrete?
Concrete made from cement, silica fume, fine and coarse aggregate, and water.
What are the desirable properties of silica fume concrete?
Compressive strength, flexural strength, and bond strength of silica fume is better than normal strength concrete. In addition, the durability of this type of concrete fend off most aggressive chemical attacks.
What are the properties of fresh silica fume concrete?
Low workability, considerably cohesive, low bleeding and segregation, and low slump value.
What are the advantages of silica fume concrete?
High durability, segregation and bleeding, efficient finishing process, high early compressive strength., high flexural strength and modulus of elasticity, high bond strength., and suitable for mass concreting since it prevents thermally induced cracking.
What are the applications of silica fume concrete is civil engineering?
The applications of the silica fume concrete in construction are high rise buildings, parking structure, dam structure, nuclear waste storage facility, and shotcrete rehabilitation.