WHAT IS SELF CONSOLIDATING CONCRETE - PROPERTIES, ADVANTAGES AND DISADVANTAGES

Self Consolidating Concrete

Self consolidating concrete is a concrete mix which has a low yield strees, high deformability, good segregation resistance and moderate viscosity.It is a highly flowable type of concrete that spreads into the form without the need of mechanical vibration.Self compacting concrete is highly flowable, non-segregating concrete with a slump flow of 20 - 30 inches that can spread into place fill the formwork and encapsulate the reinforcement without any mechanical consolidation.

In self consolidating concrete sometimes superplasticizers and viscosity modifier are added in the mix to minimize bleeding and segregation in the concrete mix.A well designed SCC has high deformability and excellent stability against segregation.

Self consolidating concrete has similar water-cement ratio or cement binder ratio as compared to the ordinary concrete mix.It give slightly higher strength because without the use of the vibrator at the time of concrete pouring, it will improve the bond between the concrete hardened paste and aggregates.

In self consolidating concrete the SCC mix must be placed at a higher velocity than that of regular concrete.It has been poured into the slab or in columns more than the hight of 5 m without segregation of aggregate because of SCC design. 

Materials Used For Self Consolidating Concrete

1. Cement

Ordinary Portland cement of grade 43 or 53 is used in self consolidating concrete.

2. Aggregates

The aggregates which can used in SCC is limited to 16 mm.The aggregates are well graded either round or cubical in shape.The fine aggregates used in SCC must have 4.75 mm maximum in size.

3. Water

The quality of water is same as used in reinforced concrete and pre-stressed concrete construction.

4. Mineral Admixtures

The admixtures used in SCC are as fallows:

• Fly Ash: It improves the quality and durability of self consolidating concrete structures.

• Silica Fumes: It increase the mechanical properties of  self consolidating concrete structures.

• Stone Powder: It improves the powder content of  self consolidating concrete structures.

• GGBS: Ground granulated blast furnace slag helps to improve the rheological properties of  self consolidating concrete.

Properties of Self Consolidating Concrete

1. Filling Ability 

This property of the concrete is the ability to flow under its own weight without any vibration provided intentionally.

2. Passing Ability

This property is the ability of the concrete to maintain its homogeneity.

3. Segregation Resistance

This is the resistance of the concrete not to undergo segregation when it flows during the self compaction process.

Advantage of Self Consolidating Concrete

• The quality of the construction is high.
• It improves the structure integrity.
• It provide high strength to the structures.
• It reduces labour cost.
• It reduces time during placing of concrete.
• It reduces the noise level of mechanical vibrators.
• It allows innovative architectural features.
• It provides wide variety of placement techniques.
• It has excellent flow even around heavy reinforcement areas.
• The durability of concrete structure is high compared to normal concrete structure.

Disadvantage of Self Consolidating Concrete

• Low density.
• Low fire resistance.
• It is more costly than conventional concrete.
• Highly skilled workers are required for the production of SCC.
• Lack of globally accepted test standard to undergo SCC mix design.
• Increased plastic shrinkage potential.