Test For Self Compacting Concrete - Slump Flow Test, L-Box Test

Slump Flow Test, L-Box Test, U-Box Test, J-Ring Test and V-Funnel Flow Time Test are performed on self compacting concrete to check quality of concrete. In this blog post you will read about this test in detail. 

Slump Flow Test of Self Compacting Concrete

Slump flow test is used to determine the flow-ability of the self compacting concrete. This test is performed for assessing the quality and consistency of the concrete.

In slump flow test, we measure the spread of self compacting concrete when it is poured into a cone shaped mold and then the mold is removed.

The spread of the self compacting concrete is measured in all directions and the average value is calculated. The result of the test is expressed in millimeter and it provides an indication of the workability and filling ability of the concrete.

Procedure For Slump Flow Test:

The slump flow test is conducted using a slump cone that is 300 mm in height, 200 mm in diameter at the top and 300 mm in diameter at the bottom.

1. The slump cone is placed on a flat, level surface and it is moistened with water to prevent the self compacting concrete from sticking to the cone.
2. The cone is filled with the concrete in three layers and each layer is tamped 25 times using a standard tamping rod.
3. After the final layer is tamped, the top surface of the self compacting concrete is struck off using the tamping rod.
4. The cone is lifted vertically and the self compacting concrete flows freely into a circular shape on the base plate.
5. The spread of the self-compacting concrete is measured using a ruler and the average value is calculated.
6. The result of slump flow test of self compaction concrete is given in millimeter.

Click: Self-Compacting Concrete in Detail.

Significance of Slump Flow Test

The slump flow test is significant in several ways.
Firstly, it provides an indication of the flowability and filling ability of the self compacting concrete.
The test result is essential for assessing the quality and consistency of the concrete.

Secondly, the slump flow test is a standard test used in the construction industry and it ensures that the self compacting concrete meets the required standards and specifications.

Also, the slump flow test is a quick and easy test that can be conducted on-site, providing immediate feedback on the quality and performance of self compacting concrete.

T50 Time Test of Self Compacting Concrete

T50 time test is a test to measure the setting time of cement-based materials like concrete and mortar. This test represents the time taken for the cement-based material to reach 50% of its final set strength. T50 time test is important in determining the ideal time for finishing and curing concrete and mortar.

T50 Time Test Procedure

The T50 time test is conducted using a Vicat Apparatus which consists of a needle with a standardized weight attached to a graduated rod. 

The test is performed by placing a sample of the cement-based material in a mold and then inserting the needle of the Vicat apparatus into the material at regular intervals. 

The time at which the needle penetrates the material to a depth of 50 mm is recorded as the T50 time.

Significance of T50 Time Test

The T50 time is an important factor in determining the ideal time for finishing and curing cement-based materials. 
If the material is finished too early, it may be too weak to support the weight of subsequent construction loads. 
If the material is finished too late, it may not bond properly with other materials or may develop surface cracks due to drying.
The T50 time test can also be used to determine the effectiveness of admixtures or other additives that are added to the cement-based material to accelerate or retard its setting time. 
Admixtures can be used to adjust the T50 time to suit specific construction requirements and environmental conditions.

Click: Properties, Advantages and Disadvantages of Self Compacting Concrete.

V-Funnel Flow Time Test of Self-Compacting Concrete

The V-funnel flow time test is a simple and widely used method for measuring the flowability and workability of self compacting concrete.

Equipment Required

1. V-funnel apparatus
2. Stopwatch or timer
3. Scale
4. Funnel cleaning brush

Procedure For V-Funnel Flow Time Test

1. Weigh the empty V-funnel apparatus and record the weight.
2. Mix all the ingredients of self compacting concrete according to the desired mix design.
3. Pour the self-compacting concrete into the V-funnel until it is filled to the brim.
4. Start the timer as soon as the concrete starts to flow out of the funnel.
5. Stop the timer when the self compacting concrete flow has completely stopped.
6. Record the time taken for the self compacting concrete to flow out of the funnel.
7. Weigh the V-funnel apparatus with any remaining concrete and subtract the weight of the empty apparatus to obtain the weight of the concrete used in the test.
8. Repeat the test two more times using fresh self compacting concrete samples to obtain a total of three test results.
9. Clean the funnel thoroughly with a brush and water between tests to remove any residual self compacting concrete.
10. Calculate the flow rate by dividing the weight of the self compacting concrete by the average flow time.

Interpretation of Results

The flow time and flow rate obtained from the V-funnel flow time test can be used to assess the flowability and workability of the self-compacting concrete.

Lower flow times and higher flow rates indicate better flowability and workability, while higher flow times and lower flow rates indicate poorer flowability and workability. 

The results can also be used to optimize the mix design by adjusting the amount of admixtures or additives to achieve the desired flowability and workability.

J-Ring Test of Self Compacting Concrete

J-ring test is a common method for measuring the passing ability of self compacting concrete through narrow gaps or congested reinforcement. 

The test involves pouring self compacting concrete into a specially designed J-ring apparatus and measuring the segregation that occurs as the concrete passes through the ring.

The J-ring test is a simple and widely used method for measuring the passing ability of self-compacting concrete through narrow gaps or congested reinforcement. 

Equipment Required

1. J-ring apparatus
2. Tamping rod
3. Scoop
4. Scale
5. Stopwatch or timer
6. Funnel cleaning brush

Procedure of J- Ring Test

1. Weigh the empty J-Ring apparatus and record the weight.
2. Mix the ingredients of self compacting concrete according to the desired mix design.
3. Pour the SCC into the J-ring apparatus until it is filled to the brim.
4. Use a tamping rod to compact the concrete in the J-ring apparatus by gently tapping it on the sides of the apparatus 25 times.
5. Use a scoop to remove any excess concrete from the top of the J-ring.
6. Start the timer as soon as the concrete starts to flow out of the J-ring.
7. Stop the timer when the concrete flow has completely stopped.
8. Measure the height of the highest point of concrete within the J-ring and record it as "A".
9. Measure the height of the lowest point of concrete outside the J-ring and record it as "B".
10. Calculate the passing ability index (PAI) by subtracting "B" from "A" and dividing the result by "A".
11. Repeat the test two more times using fresh self-compacting concrete samples to obtain a total of three test results.
12. Clean the J-ring apparatus thoroughly with a brush and water between tests to remove any residual self-compacting concrete.
13. Calculate the average passing ability index (PAI) for the three test results.

Interpretation of results:

The passing ability index (PAI) obtained from the J-ring test can be used to assess the passing ability of the self-compacting concrete through narrow gaps or congested reinforcement.

Higher PAI values indicate better passing ability, while lower PAI values indicate poorer passing ability. The results can also be used to optimize the mix design by adjusting the amount of admixtures or additives to achieve the desired passing ability.

U-Box Test of Self Compacting Concrete

U-box test is used to determine the segregation resistance of self compacting concrete. This test is performed using a specially designed U-shaped box which is filled with the self compacted concrete and subjected to vibration to simulate the conditions experienced during transportation and placement.

Equipment Required

1. U-box apparatus
2. Vibrator
3. Funnel
4. Trowel
5. Ruler
6. Scale

Procedure For U-Box Test

1. Weigh the empty U-box apparatus and record the weight.
2. Mix the ingredients of self compacting concrete according to the desired mix design.
3. Fill the U-box apparatus with self compacting concrete to a level slightly above the brim.
4. Use a trowel to level the surface of the SCC.
5. Place the U-box apparatus on the vibrating table.
6. Start the vibration and continue for 5 minutes.
7. Stop the vibration and remove the U-box apparatus from the vibrating table.
8. Use a funnel to pour the self compacting concrete onto a flat surface.
9. Measure the height of the highest point of concrete and the height of the lowest point of concrete from the flat surface.
10. Calculate the segregation index by subtracting the height of the lowest point from the height of the highest point and dividing the result by the height of the highest point.
11. Repeat the test two more times using fresh self compacting concrete samples to obtain a total of three test results.
12. Clean the U-box apparatus thoroughly with water and a cleaning agent between tests to remove any residual self compacting concrete.
13. Calculate the average segregation index for the three test results.

Interpretation of Result

The segregation index obtained from the U-box test can be used to assess the segregation resistance of the self compacting concrete.

Higher segregation index values indicate better segregation resistance while lower segregation index values indicate poorer segregation resistance.

L-Box Test of Self Compacting Concrete

The L-box test is a simple and commonly used method for measuring the flowability and passing ability of self-compacting concrete. This test involves pouring self compacting concrete into a specially designed L-shaped box and measuring the height difference between the two legs of the box after the concrete has flowed through it.

Equipment Required

1. L-box apparatus
2. Tamping rod
3. Scoop
4. Scale
5. Stopwatch or timer
6. Funnel cleaning brush

Procedure For L-Box Test

1. Weigh the empty L-box apparatus and record the weight.
2. Mix the ingredients of self compacting concrete according to the desired mix design.
3. Pour the self compacting concrete into the upper opening of the L-box until it is filled to the brim.
4. Use a tamping rod to compact the concrete in the L-box by gently tapping it on the sides of the apparatus 25 times.
5. Use a scoop to remove any excess concrete from the top of the L-box.
6. Start the timer as soon as the concrete starts to flow out of the L-box.
7. Stop the timer when the concrete flow has completely stopped.
8. Measure the height of the concrete surface in both legs of the L-box and record them as "A" and "B".
9. Calculate the flow spread ratio (FSR) by dividing the lower height (B) by the upper height (A).
10. Repeat the test two more times using fresh self compacting concrete samples to obtain a total of three test results.
11. Clean the L-box apparatus thoroughly with a brush and water between tests to remove any residual self compacting concrete.
12. Calculate the average flow spread ratio (FSR) for the three test results.

Interpretation of Result

The flow spread ratio (FSR) obtained from the L-box test can be used to assess the flowability and passing ability of the SCC.

Higher FSR values indicate better flowability and passing ability, while lower FSR values indicate poorer flowability and passing ability.

Also Read: Self Compacting Concrete - Overview.