What Is Self Compacting Concrete?
Self Compacting Concrete or SCC concrete is the concrete that is capable to compact under its own load without any use of mechanical vibration. In the past, making concrete structures without compaction and vibration have been done but failed to achieve the objectives. For examples, placing of concrete underwater is done without vibration, mass concrete and shaft concrete can be well placed without compaction. But the examples of these concretes are generally of lower strength and it is difficult to obtain uniform quality.
The Invention of Self Compacting Concrete:
Recognizing the need for uniformity and complete compaction of concrete, the Scientists at the University of Tokyo, Japan; started to develop Self Consolidating Concrete. By the early 1990s, Japan has developed and adopted self-consolidating concrete that doesn’t require vibration to attain full compaction.
Without compromising on strength and the characteristics of concrete; SCC concrete is one of the biggest revolutions in the construction industry that will last for several decades.
Advantages of SCC Concrete:
Considering the properties of self-leveling concrete, it has numerous advantages to the construction. Earlier SCC concrete was invented to cater the shortage of skilled labor in JAPAN, but now noticeable features are:
- Faster Construction.
- Reduction in site manpower.
- Better surface finish.
- Easier Placing.
- Improved durability.
- Greater freedom in design.
- Thinner concrete sections.
- Reduced Noise Level.
- Safer working Situation.
- Superior in strength and durability.
Disadvantages of SCC Concrete:
Comparing with the advantages, the disadvantages of self-leveling concrete are almost negligible that can easily cater by proper attention during execution which are:
- Due to high fluidity or flowing power, formwork should be leakproof.
- Chances of occurrence of plastic shrinkage due to low water-cement ration in concrete.
- Skilled workers required to handle flowing concrete.
Ingredients of Self Leveling Concrete:
- Cement: Ordinary Portland cement, 43 or 53 grade can be used.
- Aggregates: The maximum size of the coarse aggregate is usually restricted to 20 mm. Well graded cubical or rounded aggregates are desirable. Aggregates should be of uniform quality regarding shape and grading. Fine aggregates may be natural or manufactured. The grading should be uniform throughout the work.
- Water: Water quality should be established on a similar line like that for using RCC or Pre-stressed concrete.
- Chemical Admixtures: Superplasticizers are an important part of Self Compacting Concrete to provide necessary workability. The new generation superplasticizers termed Poly-carboxylate ethers (PCE) is particularly helpful for Self Compacting Concrete.
- Mineral Admixtures: Fly ash, Blast furnace slag, Stone Powder, Silica Fumes, Fibers may be used to improve the properties of Self Compacting Concrete.
Uses of Self Leveling Concrete:
This special concrete has several uses in the industry some of which are mention below:
- Used in Bridges
- Drilled shafts
- High Length Columns
- Those areas which have high-density steel meshing or conducting.
Key Fact: Akashi-Kaikyo Suspension Bridge is an example of SCC concrete.
Self Compacting Concrete Mixes:
There are three ways in which self-leveling concrete can be made:
- Powder Type
- VMA Type (Viscosity Modifying Admixture)
- Combined Type
Concluding: How Economical is SCC Concrete?
There is a feeling that the cost of Self Compacting Concrete is much higher than that of the corresponding ordinary or high strength concrete. It is seen that the cost of materials of Self Compacting Concrete is about 10-15% higher. If one takes the other components of costs such as cost of compaction, finishing, etc. then one would realize that Self Compacting Concrete is certainly not a costly concrete for comparable strength.