Self-compacting concrete (SCC) is a type of concrete that possesses specific properties, including excellent filling ability, passing ability, and segregation resistance. These properties make SCC highly desirable for applications where traditional concrete may not be suitable due to its lack of workability. To assess the workability of SCC, several testing methods are available, such as slump flow tests, V-funnel test, L-box test, U-Box test, Fill box test, among others. These tests help determine the flow characteristics, passing ability, and resistance to segregation of SCC, making them crucial in ensuring the quality and performance of SCC in various construction applications.
Test Methods for Self Compacting Concrete
The test methods described in this presentation are specifically designed for self-compacting concrete. Other existing rheological test procedures have not been included in this discussion, although the correlation between the results of these tests and the rheological properties of the concrete is expected to be an important aspect of future research, including standardization efforts.
When evaluating these tests, it’s important to consider several points. First, there may not be a clear correlation between test results and actual performance on site. Second, there may be limited precise data available, making it challenging to establish clear compliance limits. Lastly, in order for a concrete mix to be classified as self-compacting concrete, it must meet the requirements for three workability properties: filling ability, passing ability, and segregation resistance.
Filling Ability of Self Compacting Concrete
The flowability of self-compacting concrete (SCC) is its ability to easily flow and fill all spaces within the formwork under the force of gravity, without the need for external vibration or compaction. Various tests, such as slump flow and V-funnel tests, are commonly used to assess the filling ability of fresh SCC. These tests help determine the ability of SCC to flow effortlessly into complex and congested formwork configurations, ensuring that the concrete adequately fills all voids and achieves complete consolidation without the need for manual compaction.
Passing Ability of Self Compacting Concrete
The flowability of self-consolidating concrete (SCC) refers to its ability to flow easily through narrow openings, such as the gaps between steel reinforcing bars, without the need for external forces. This property can be evaluated using various test methods, including the U-box, L-box, Fill-box, and J-ring tests. These tests assess the passing ability of SCC, which is crucial for its performance in construction applications.
Segregation Resistance
Self-compacting concrete (SCC) is required to meet specific criteria related to filling ability, passing ability, and uniform composition during the entire process of transport and placing. SCC needs to have excellent filling ability, meaning it can easily flow and fill all the intricate spaces within the formwork without any need for external compaction. Additionally, it should possess passing ability, allowing it to flow smoothly around obstacles and through congested areas without any blockages. Finally, SCC should maintain a consistent composition throughout its transportation and placement process to ensure uniformity in its properties and performance. Meeting these requirements ensures that SCC can be efficiently transported and placed with ease, resulting in high-quality and durable concrete structures.
Workability of Self Compacting Concrete
There are several test methods available to determine the workability of Self Compacting Concrete (SCC). These tests are specifically designed to assess the ability of SCC to flow and fill intricate formwork without the need for excessive vibration or compaction.
One commonly used test method for evaluating the workability of SCC is the Slump Flow Test. This test involves pouring a representative sample of SCC into a cone-shaped mold, and then measuring the spread or diameter of the concrete flow after the cone is removed. The spread of the concrete is an indicator of its ability to flow and fill the formwork without segregation or blockage.
Another test method used for determining SCC workability is the V-Funnel Test. In this test, a sample of SCC is poured into a V-shaped funnel and the time taken for the concrete to flow through the funnel is measured. This test provides an indication of the viscosity and flowability of SCC, as well as its resistance to segregation.
The L-Box Test is another test method commonly employed to evaluate the workability of SCC. In this test, a sample of SCC is poured into a specially designed L-shaped box, and the time taken for the concrete to flow through the box is measured. This test assesses the ability of SCC to flow and fill confined spaces without segregation or blockage.
Furthermore, the J-Ring Test is utilized to determine the passing ability of SCC through narrow gaps or congested reinforcement. In this test, a sample of SCC is poured into a ring-shaped mold with a protruding arm, and the ability of the concrete to flow around the arm without blocking is evaluated.
These test methods provide valuable information about the workability of SCC, allowing engineers and contractors to ensure that the concrete can be easily placed and compacted without any issues, thus ensuring a high-quality end product.
1. Slump flow test
The slump flow test is a commonly used procedure to evaluate the ability of self compacting concrete to flow horizontally without any hindrances. This test method is derived from the traditional slump test, which is used to determine the consistency of conventional concrete. However, the slump flow test specifically focuses on assessing the horizontal flow characteristics of self compacting concrete, without any obstructions in its path. This test provides valuable information about the flowability and workability of self compacting concrete, which is essential for ensuring its proper placement and performance in construction applications.
2. V Funnel Test
The V-funnel test is commonly used to measure the flowability of self-compacting concrete. However, it’s important to note that the flowability of concrete can be influenced by various other properties of the concrete. These properties may affect how the concrete flows during testing using the V-funnel, which is a crucial consideration in interpreting the results of the test.
3. L Box Test
The assessment in question measures both the flow of concrete and its susceptibility to blockage by reinforcement.
4. U Box Test
The U Box test, also known as the “box shaped” test, is a method used to measure the filing ability of self compacting concrete. It was developed by the Technology Research Centre of the Taisei Corporation in Japan. The U Box test is specifically designed to assess the ability of self compacting concrete to fill confined spaces, and it provides valuable information on the flowability and workability of the concrete mixture. This test is widely used in the construction industry to evaluate the performance of self compacting concrete in terms of its ability to flow and fill molds or formworks without the need for external compaction. By measuring the filing ability of self compacting concrete using the U Box test, engineers and construction professionals can ensure that the concrete mixture meets the required specifications for proper placement and compaction, resulting in high-quality and durable concrete structures.
5. Fill Box Test
The Fill Box Test, also known as the Kajima Test, is a method used to evaluate the filling ability of self-compacting concrete that contains aggregates with a maximum size of 20 mm. This test is specifically designed to measure how effectively the self-compacting concrete can flow and fill a box without the need for external consolidation or vibration. By determining the filling ability of the self-compacting concrete, the Fill Box Test helps assess its workability and flow properties, which are important factors in ensuring proper placement and compaction during construction.