What is Self-Compacting Concrete (SCC)?
Self-compacting concrete (SCC) is a highly flowable, non-segregating concrete mix that can spread into place, fill formwork, and encapsulate reinforcement without the need for mechanical vibration. SCC was developed to address the challenge of placing concrete in heavily reinforced or complex-shaped elements, improving productivity, surface finish, and durability.
Key Features of SCC:
Flows and consolidates under its own weight.
Achieves complete compaction and uniformity, minimizing voids and honeycombing.
Reduces labor and noise (no need for vibration).
Excellent surface finish and reduces repair work.
Main Standards for SCC
Several international standards and guidelines govern the production, testing, and acceptance of SCC, including:
EN 206: “Concrete – Specification, performance, production, and conformity” (European Union)
EFNARC Guidelines: “Specification and Guidelines for Self-Compacting Concrete”
ASTM C1611/C1611M: “Standard Test Method for Slump Flow of Self-Consolidating Concrete”
ASTM C1621/C1621M: “Passing Ability of Self-Consolidating Concrete by J-Ring”
ASTM C1712: “Rapid Performance Test for Self-Consolidating Concrete Using L-Box Apparatus”
ACI 237R-07: “Self-Consolidating Concrete” (American Concrete Institute Report)
IS 5512: Indian Standard for Self Compacting Concrete
Laboratory and Field Tests for SCC
SCC cannot be properly controlled by the traditional slump test alone (since high flow could mean segregation). Instead, several specialized tests are used:
Slump Flow Test (ASTM C1611, EFNARC)
Measures the horizontal flow (spread) of SCC after the Abrams’ slump cone is lifted.
Target range: 550–850 mm.
Indicates filling ability.
T500 Time
The time SCC takes to reach a 500 mm spread during the slump flow test.
Indicates viscosity (lower time = higher flowability).
J-Ring Test (ASTM C1621)
Measures passing ability; the J-Ring simulates congestion from reinforcement.
Compared with slump flow: smaller difference means better passing ability.
L-Box Test (ASTM C1712, EFNARC)
Assesses passing ability and potential blockage by reinforcement.
Ratio H2/H1 indicates ability to flow through obstacles (target: ≥ 0.8 for good SCC).
U-Box Test (EFNARC)
Similar to L-Box; assesses filling ability and flow through reinforcement simulating walls or columns.
V-Funnel Test (EFNARC)
Measures the time SCC needs to flow through a narrow opening (fluidity/viscosity).
Target: 6–12 seconds for standard mixes.
Segregation Resistance (GTM Screen Stability Test, EFNARC)
Evaluates SCC's ability to remain homogenous (no aggregate separation).
Summary Table: SCC Test Methods
| Property | Test (Standard/Reference) | Typical Value for SCC |
|---------------------|-------------------------------------|--------------------------|
| Filling Ability | Slump Flow (ASTM C1611, EFNARC) | 550–850 mm |
| Passing Ability | J-Ring (ASTM C1621) | Difference < 50 mm |
| Passing Ability | L-Box (H2/H1) | ≥ 0.8 |
| Viscosity | V-Funnel (EFNARC) | 6–12 s |
| Segregation Resist. | GTM Screen (EFNARC) | ≤ 15% water bleed |
Applications of SCC
Highly reinforced structural elements (columns, beams, walls)
Precast concrete industry
Architectural and exposed finish structures
Repairs and rehabilitation where good compaction is hard to achieve
For more information, supply, or technical consulting for SCC in Iran, you can contact the leading expert and supplier, Clinic Beton Iran:
https://www.clinicbeton.com
International Brand: https://www.rbs-contech.com