Self compacting concrete (SCC) is a special type of concrete that has been innovated to be used for situations that need specific consideration. Self compacting concrete (SCC) flows under its own weight and does not need external vibration to compact. Self compacting concrete (SCC) is used in construction where concrete vibrators can not be utilised for compaction of concrete. In this blog, we will learn in detail regarding self compacting concrete (SCC), the ingredients used to make it, benefits and drawbacks, its properties, and its applications.
What is Self Compacting Concrete (SCC)?
Self compacting concrete (SCC) is the most popular type of concrete. It is also known as self-consolidating concrete. Self compacting concrete (SCC) has excellent flow ability in its fresh condition, conducting self and ingredient consolidation without segregation problems.
Self compacting concrete (SCC) has non-segregation properties that can settle into a deep, narrow portion of formwork and cover whole reinforcement with its own weight.
Unlike nominal concrete, which requires mechanical tools such as needle vibrators, Self compacting concrete (SCC) does not need any vibrator to compact it. When it is not possible to compact concrete using vibrators, self compacting concrete (SSC) is used.
To reduce segregation and bleeding problems, certain mixtures self compacting concrete (SCC) utilise some admixtures like viscosity modifier, plasticizers and superplasticizers etc. Due to segregation in concrete, some honeycomb parts show on the surface. Although, well-designed self compacting concrete (SCC) will not segregate because of its stability and plasticity.
Ingredients used to make Self Compacting Concrete (SCC)
The following are the main materials used in the self compacting concrete (SCC) production.
Cement
Self compacting concrete (SCC) can be produced with nominal/Ordinary Portland Cement (OPC) in 43 or 53 grades.
Aggregate
The aggregate size used in self compacting concrete (SCC) design is limited to 20mm. If the structural reinforcement is complex, the size of aggregate can be 10mm to 12mm. The good selection is well-graded aggregates in cubical or round shapes.
Fine aggregates (FA) utilised in self compacting concrete (SCC) can be either M-Sand (uniformly graded produced aggregates) or natural aggregates. Fine aggregates (FA) with particle sizes less than 125 micron are generally used.
Water
The quality of water should be the same as in prestressed concrete and reinforced concrete construction.
Mineral Admixtures
The utilisation of mineral admixtures is dependent on the mix design of concrete and required qualities. There are many mineral admixtures that can be utilised, and the properties they give are given below.
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- Fly Ash : The fine fly ash minerals help in filling the interior concrete structure, resulting in low pores. This improves the durability and quality of structure.
- Stone Powder : Stone powder is utilised in self compacting concrete (SCC) to improve the powder content of mixture.
- Blast Furnace Slag : It is also known as GGBS (Ground Granulated Blast Furnace Slag). The addition of it increases the flowability of self compacting concrete (SCC).
- Silica Fumes : The addition of silica fumes improves mechanical qualities of self compacting concrete.
Chemical Admixtures
Chemical admixtures such as superplasticizers are many times used in the design of self compacting concrete (SCC). Air entraining agents are utilised to improve the freezing and thawing resistance of concrete. Retarders are used to control setting time of concrete.
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Properties of Self Compacting Concrete (SCC)
Self compacted concrete (SCC) and conventional vibrated concrete with comparable qualities and comparable compressive strength. Hence, Self compacted concrete (SCC) can be used in most applications where conventional concrete is used.
Although, the property of self compacted concrete (SCC) is different from that of traditional concrete, and the variation exists in the performance during the fresh condition of concrete; not much difference in the sense of hardened condition of concrete. To satisfy the quality of self compacted concrete (SCC), the aspect of workability that affects its flowability and segregation resistance must all be properly regulated.
- Flowability : This property of concrete refers to its capability to flow under its own weight without any needful vibration.
- Segregation resistance : This property of concrete refers to resistance to segregation as it flows under the self compaction process. Due to its particular admixtures such as plasticizer and mineral admixtures, self compacting concrete (SCC) is resistant to segregation.
The above explained properties of self compacting concrete (SCC) must be handled when placing it.
Benefits of Self Compacting Concrete (SCC)
The main benefits of self compacting concrete (SCC) are as follow:
- The vibration related problems have been resolved. Noise of vibration is reduced.
- Self compacting concrete is easily placed, which results in notable cost saving.
- Permeability of concrete structure is decreased due to self compacting concrete having a high filling ability.
- Self compacting concrete can construct innovative architectural concrete constructions.
- The labour cost is decreased as there is no need for labours to vibrate the concrete.
- Self compacted concrete decreases cavities in heavily reinforced concrete structures.
- Self compacted concrete allows easier pumping than traditional concrete. As a result, Self compacted concrete can be pumped more efficiently across more heights and distances.
Drawbacks of Self Compacting Concrete (SCC)
Self compacted concrete, like any other construction materials, has the following drawbacks.
- The ingredients used for making self compacting concrete have to be selected very intentionally. Hence, the ingredients selection process becomes more strict.
- It requires a number of trial batches and laboratory tests.
- Due to greater flowability compared to conventional concrete may result in a dynamic pressure as well as hydrostatic pressure on formwork.
- There is no recognised test standard for self compacting concrete mix. Hence, keeping quality standards can be challenging while using self compacted concrete.
Conclusion
It is necessary to note that the design of self compacting concrete needs intentional consideration of the mix proportion, including the selection of proper cementitious materials, chemical admixtures, mineral admixtures and aggregates.
Proper quality control systems are important to ensure uniform performance and satisfy the necessary requirements of the project.
Finally, Self compacting concrete (SCC) offers various benefits such as workability, flowability, durability, aesthetics and structural integrity making it a preferred selection in different construction uses.
FAQs on Self Compacting Concrete
What is SCC used for?
Self compacting concrete (SCC) is used in construction where concrete vibrators can not be utilised for compaction of concrete.
What is the full form of SSC concrete?
The full form of SCC is Self Compacting Concrete.
What is the slump range of SCC?
The slump range of SCC from 18 to 32 inches (455 mm to 810 mm)
Why is SCC concrete used?
Self compacting concrete (SCC) has excellent flow ability in its fresh condition, conducting self and ingredient consolidation without segregation problems.
What is self-compacting concrete?
Self compacting concrete (SCC) is the most popular type of concrete. It is also known as self-consolidating concrete. Self compacting concrete (SCC) has excellent flow ability in its fresh condition, conducting self and ingredient consolidation without segregation problems.
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