What is Self-Compacting Concrete
One of the most popular types of concrete is self-compacting concrete (SCC), also referred to as self-consolidating concrete. This is mainly due to its self-compacting qualities and strength. Self compacting concrete has excellent deformability and is highly flowable in its fresh state. Self compacting concrete is a special type of non-segregating concrete that can settle into formwork and encapsulate heavily reinforced, narrow, and deep sections by its weight.
Self- compacting concrete does not require external force or vibration to be compacted, unlike traditional concrete, which uses mechanical equipment such as immersion vibrators. Self- compacting concrete is employed in construction when it is difficult to consolidate concrete with vibrators.
See also: Where and how to use concrete walls?
Self compacting concrete: Materials used to make this concrete
1. Portland cement
Ordinary/ regular Portland cement of grades 43 or 53 may be utilised in making Self- compacting concrete
The maximum aggregate size that can be used for Self- compacting concrete design is 20mm. The aggregate size utilised can range from 10 to 12 mm if the reinforcement used for the structure is crowded. The ideal option is well-graded aggregates in either a round or cubical shape. Both natural aggregates and manufactured aggregates (M-Sand) with a consistent grade may be utilised as the fine aggregates in Self- compacting concrete. In most cases, fine aggregates with particle size less than 0.125mm are used for Self- compacting concrete.
The water quality used for Self- compacting concrete design is the same as what is used for prestressed and reinforced concrete construction.
See also: Types of building materials
4. Mineral admixtures
Depending on the qualities needed and the mix design, different minerals can be employed as admixtures. The different mineral admixtures that can be utilised, along with the corresponding features they offer, are listed below.
- Ground Granulated Blast Furnace Slag (GGBS): enhances the rheological characteristics of self-compacting concrete.
- Fly ash: The little fly ash particles contribute to the interior concrete matrix being filled better and with less porosity. As a result, the SCC constructions are of higher quality and resilience.
- Silica fumes: Adding silica fumes to self-compacting concrete structures improves their mechanical qualities.
- Stone particle: Stone powder is used in SCC to increase the powder content of the mix.
5. Chemical admixtures
In Self- compacting concrete mix design, new-generation superplasticisers are frequently used. Air entraining agents are utilised to increase the resistance of the concrete structure to improve the freezing and thawing. Retarders are used to regulate the setting time.
Of the total volume of a self-compacting concrete, the gravel volume varies between 28% and 38%of the total volume of Self compacting concrete. The cementitious paste varies between 30% and 42% of the total volume of Self compacting concrete and the water/binder ratio is less than 0.48.
What is Smart dynamic concrete?
Smart dynamic concrete owing to its self-compacting property nature requires no vibration of very less vibration. This results in less energy and manpower consumption.
Self compacting concrete: Properties
- Self compacting concrete (SCC) is resistant to segregation because it contains unique admixtures and mineral fillers.
- Additionally, it is flexible enough to flow through crowded reinforced parts of buildings without honeycombing.
- The Self Compacting Concrete design will determine how fluid the system is.
- Concrete can be poured above 5 metres in height without any sort of segregation using a well-built SCC.
- Due to the absence of vibration, Self Compacting Concrete will have a stronger strength than standard vibrated concrete with a similar water-to-cement ratio.
- The interaction between the aggregate and the hardened paste is greatly improved as a result.
- But it’s crucial to keep in mind that Self Compacting Concrete needs to be laid more quickly than normal concrete.
Self compacting concrete benefits
Compared to conventional concrete, self-compacting concrete has several benefits. Self-compacting concrete has the following key benefits:
- Concrete construction has less permeability.
- Steel reinforcement by bonding.
- Minimises equipment wear.
- Freedom in designing innovative architectural concrete structures.
- Creates surface finishes that are smoother and more aesthetically pleasing.
- The SCC construction is faster.
- The problems associated with concrete vibration are eliminated.
- The convenience of placing the concrete leads to significant cost savings.
- Lowers the cost of labour.
- More easily constructed.
- Improves structural integrity while producing constructions of excellent grade.
- Higher than average concrete constructions in terms of durability, strength, and dependability.
- Reduced cavities in highly-reinforced regions.
- Enables simpler pumping and offers a variety of positioning strategies.
- Since no vibration is necessary during placement, noise is reduced.
- Lower pumping pressures are necessary for SCC. As a result, concrete can be pumped more efficiently over greater distances and heights as compared to typical concrete.
Self compacting concrete: Disadvantages
Self-compacting concrete has the following restrictions, much like any other building material:
- The process of selection of materials is more rigorous.
- Costs for building rise in comparison to traditional concrete construction.
- To employ a planned mixture, numerous trial batches and laboratory tests are necessary.
- For formwork design, the increased flow velocity of SCC in comparison to standard concrete might result in adynamic pressure in addition to the hydrostatic pressure of poured concrete.
Self-Compacting Concrete uses
Self-Compacting Concrete uses is mostly used for the following purposes:
Building structures requiring intricate reinforcement.
- Construction projects, including repairs, restoration, and renewal, require SCC.
- With the use of SCC, retaining walls are built that are extremely sturdy and long-lasting.
- SCC is used in the raft and pile foundation construction process.
- Building earth retaining structures.
- Drilled shafts
Self compacting concrete: Special considerations while using it
Concrete that self-compacts has advantages and expedites building. However, the following needs particular attention:
- Due to SCC’s high fluidity and the possibility of spilling along the road, which could result in contamination and environmental dangers, utilising mixers at maximum capacity is not advised.
- Formwork needs to be built to handle the pressure of the fluid concrete, which will be higher than the pressure of conventional concrete.
- Self-Consolidating Concrete may have to be placed in and lifted in taller elements.
- SCC production demands more skill and attention than normal concrete.
- Self-consolidating concrete can add up to Rs 4000 per yard to your construction costs. The price will differ amongst ready-mix concrete manufacturers.
- Self-compacting concrete production demands more skill and consideration than conventional vibrated concrete.
- The utilised formwork needs to be built to bear more pressure than it would with conventional concrete.
Self compacting concrete: Factors affecting it
Self-compacting concrete shouldn’t be applied haphazardly. Self-compacting concrete’s performance and behaviour can be influenced by the following factors:
- Warm conditions.
- The flowability of self-compacting concrete can be decreased over long distances.
- On-site delays may have an impact on the effectiveness of the concrete mix design.
- Self-Compacting Concrete may not always increase in flowability as intended, and job site water addition may result in stability issues.
How to improve the mechanical properties of self-compacting concrete?
Adding silica fumes to self-compacting concrete structures improves its mechanical qualities.
Does self-compacting concrete need vibration?
Due to its superior deformability, self-compacting concrete (SCC) is a unique kind of concrete that can be installed and consolidated under its own weight without the need for vibration exertion.