Self-Compacting Concrete (SCC): V-Funnel Test Procedures and Applications

What Is Self Compact Concrete?

Making concrete structures without vibration has been done in the past. For example, the placement of concrete under-water is done by the use of tremie without vibration.

Shaft concrete and mass concrete may be successfully placed without vibration. But the above examples of concrete are normally of lower strength and difficult to obtain consistent quality. Modern application of SCC (self-compacting concrete) is focussed on high performance, better and more reliable, and uniform quality.

List of Test Methods for Workability Properties of Self Compacting Concrete (SCC).

1. Slump flow by Abrams cone.

2. T_{50 cm} Slump flow

3. J-ring

4. V-funnel

5. V-funnel at T₅ minutes

6. L-box

7. U-box

8. Fill-box

9. GTM Screen Stability Test

10. Ouimet

In this article, we are discussion & Procedure Slump Flow Test  

V-Funnel Test and V-Funnel Test at T₅ min.

What Is V-Funnel Test?

This test was developed in Japan. The equipment consists of a V-shaped funnel shown in the above figure. The V- Funnel test is used to determine the filling ability (flowability) of the concrete with a maximum size of aggregate 20 mm size.

The funnel is filled with about 12 liters of concrete. Find the time taken for it to flow down. After this, the funnel can be filled with concrete and left for 5 minutes to settle. If the concrete shows segregation then the flow time will increase significantly.

Equipment V-Funnel Test.

V-funnel

V-funnel, as shown in the above figure, made of steel, with a flat, horizontal top and placed on vertical supports, snd with a momentary releasable watertight opening gate

Bucket 12 liters

This bucket use of a collection of concrete

Trowel

This tool is used to place cement mortar.

Scoop

This use in QC department for the material.

Stopwatch

Use for time record

Procedure V-Funnel Test.

1. About 12 liters of concrete is needed for the test.
2. Set the V-funnel on firm ground.
3. Moisten inside of the funnel.
4. Keep the trap door open to remove any surplus water.
5. Close the trap door and place a bucket underneath.
6. Fill the apparatus completely with concrete.
7. Compaction or tamping is done.
8. Strike off the concrete level.
9. Open within 10 seconds the trap door and record the time taken for the concrete to flow down.
10. Record the time for emptying.
11. This can be judged when the light is seen when viewed from the top.
12. The whole test is to be performed within 5 min.

Procedure for V-funnel flow time at T₅ mm

1. Do not clean or moisten the inside surface of the funnel.
2. Close the trap door and refill the V-funnel immediately after measuring the flow time.
3. Place the bucket underneath.
4. Fill the apparatus completely with concrete without tamping or tapping.
5. Strike off the concrete level with the top by trowel.
6. Open the trap door after 5 minutes after the second fill of the funnel and allow the concrete to flow.
7. Calculate the time taken for complete discharge.
8. It is called the flow time at T₅ min.
9. For V-funnel test the flow time should be between 8 and 12 seconds.
10. For V-funnel flow time at T₅ min. + 3 seconds is allowed.

Calculations V-Funnel Test

V-funnel flow time (t_v) = _________ sec

Results V-Funnel Test

The V-funnel flow time t_v is the period from releasing the gate until first light enters the opening, expressed to the nearest 0.1 seconds.

(t_v) = _________ sec

Conclusion V-Funnel Test:

1. This test measures the ease of flow of the concrete; shorter flow times indicate greater flowability.
2. For SCC a flow time of 10 seconds is considered appropriate.
3. The inverted cone shape restricts flow, and prolonged flow times may give some indication of the susceptibility of the mix to blocking.
4. After 5 minutes of settling, the segregation of concrete will show a less continuous flow with an increase in flow time.

Frequently Asked Questions (FAQ) on Self-Compacting Concrete (SCC) and V-Funnel Test

What is Self-Compacting Concrete (SCC)?

Self-Compacting Concrete (SCC) is a high-performance concrete that can flow and consolidate under its own weight, without the need for mechanical vibration. It ensures uniform quality, high strength, and better reliability compared to traditional concrete.

Why is SCC preferred over traditional concrete?

SCC is preferred for its ability to flow into complex forms and tight spaces without segregation or voids, ensuring a smoother finish and higher structural integrity. It also reduces labor and equipment costs associated with mechanical vibration.

What is the V-Funnel test for SCC?

The V-Funnel test is a method used to determine the flowability and filling ability of SCC. It measures the time taken for a specified volume of concrete to flow through a V-shaped funnel.

What equipment is required for the V-Funnel test?

The equipment needed includes:

1. V-funnel made of steel
2. 12-liter bucket
3. Trowel
4. Scoop
5. Stopwatch

How is the V-Funnel test conducted?

1. Fill the V-funnel with about 12 liters of concrete.
2. Record the time taken for the concrete to flow out.
3. Repeat the process after 5 minutes to observe any changes in flow time due to segregation.

What does the flow time in the V-Funnel test indicate?

The flow time indicates the ease of flow of the concrete. Shorter flow times suggest higher flowability, while longer times may indicate potential issues with the mix, such as segregation or blocking.

What are the acceptable flow times for the V-Funnel test?

For SCC, a flow time of 8 to 12 seconds is considered appropriate. For the V-Funnel flow time at T5 minutes, an additional 3 seconds is allowed.

What is the significance of the V-Funnel flow time at T5 minutes?

The V-Funnel flow time at T5 minutes assesses the stability of the concrete mix over time. An increase in flow time after 5 minutes can indicate segregation and reduced flowability.

How is the V-Funnel test result recorded?

The V-Funnel flow time is recorded as the period from releasing the gate until the first light is seen at the opening, expressed to the nearest 0.1 seconds.

Why is the V-Funnel test important for SCC?

The V-Funnel test is crucial for evaluating the flowability and stability of SCC, ensuring that the mix can fill forms completely and maintain its quality over time, which is essential for structural integrity and durability.