The Vee Bee Consistometer Test is a widely used method to determine the workability of fresh concrete, especially for mixes with low slump where the traditional slump test is not suitable. This test measures the time required for a concrete sample to change from a molded cone shape to a fully vibrated, compacted state under mechanical vibration. It provides valuable insights into the flow and handling properties of concrete, helping engineers ensure proper placement and compaction on-site. Read this blog to understand what the Vebe Test is, the procedure for conducting the test, and the IS codes related to it.
What is the Vee Bee Consistometer Test?
The Vee Bee Consistometer Test is a laboratory procedure used to assess the workability and consistency of fresh concrete. In this test, a concrete sample is molded into a standard cone shape and subjected to vibration through a Vee Bee Consistometer. It is mainly designed for dry concrete with a minimal water-to-cement ratio. To determine the workability of low-workability mixes, where slump tests are less reliable, V. Bahrner developed this test. The time it takes for the concrete to transform into a fully compacted cylindrical shape is recorded as the Vee Bee time, which indicates the concrete’s workability. Shorter Vee Bee times correspond to higher workability, while longer times indicate stiffer mixes. This method is particularly useful for low-slump or very stiff concrete mixes that cannot be evaluated accurately using the slump test.
What are the Vee Bee Test Apparatus?
The following is the main Vee Bee test apparatus setup used in the laboratory:
- Vee Bee Consistometer: This is the main setup, containing a vibrating table resting on elastic supports, with dimensions of 380 mm in length and 260 mm in width. Placed at a height of 305 mm from the floor.
- A Cylindrical Container: A sheet metal slump cone with openings at both ends, with top and bottom diameters of 200 mm and 100 mm, and a height of 300mm.
- Tamping rod: Straight iron rod of circular cross-section with rounded ends.
- Stopwatch: For recording time with maximum accuracy.
- Scoop: To place concrete.
- Glass Disc: A clear, flat disc attached to a rod that moves vertically through a guide sleeve mounted on a swivel arm.
Stepwise Vee Bee Consistometer Test Procedure
To carry out the Vee Bee Consistometer test, the lab performer needs to follow these steps:
Prepare the Equipment: Make sure the Vee Bee Consistometer is placed on a rigid, horizontal base. The metal cylindrical container must be strongly fixed onto the vibrating table with wing nuts and should be free from any external vibration or shock. Dampen the internal surface of the slump cone mould with a moist cloth or apply a suitable lubricant inside to avoid any sticking.
Fill the Cone: Fill the slump cone inside the cylindrical container with fresh concrete in four equal layers. Each layer should be one-fourth the height of the cone (typically 300 mm height). Tamp each layer 25 times uniformly with the rounded end of a standard tamping rod to settle the concrete mix and remove air voids. After placing the final layer, remove the excess concrete to level the surface with a trowel or strike it off.
Place the Glass Disc: Once the cone is levelled with concrete, move the transparent glass disc attached to the swivel arm and set it on top of the slump cone inside the metal pot. The disc should just touch the concrete’s top surface. Record the initial reading from the graduated scale on the rod fixed to the swivel arm.
Remove the Cone: Carefully and vertically lift the slump cone upward, allowing the concrete to settle in the cylindrical container. Then lower the glass disc onto the concrete surface and record the final reading from the graduated scale.
Calculate Slump: Calculate the slump value by taking the difference between the initial and final readings from the graduated rod.
Start Vibrator and Stopwatch: Switch on the vibrating table and simultaneously start the stopwatch to vibrate the concrete.
Observe and Record Vibration Time: Allow the concrete to be vibrated until its surface becomes smooth, uniform, and glossy, adhering completely to the glass disc. Stop the stopwatch and record the time taken for this remoulding process (in seconds.
This recorded time indicates the concrete’s workability. Lower Vee Bee seconds mean higher workability.
Calculation for the Vee Bee Consistometer Test
Slump value can be calculated by subtracting the initial slump reading from the final slump reading.
Slump Value = Final Reading – Initial Reading
Vee Bee Seconds: In the Vebe test, the time taken to transform concrete from a conical shape to a cylindrical shape under vibration is called the Vee Bee degree or Vee Bee time. It is expressed in Vee Bee seconds, indicating the workability of the concrete.
Results of Vee Bee Consistometer Test
| Vee-Bee Time (Seconds) | Workability |
| 10 – 20 | Very Low |
| 5 – 10 | Low |
| 2 – 5 | Medium |
IS Code for the Vee Bee Consistometer Test
IS 1199:1959 provides guidelines for performing the Vee Bee Consistometer test, which is used to determine the workability of dry concrete mixes. The standard details the apparatus dimensions, testing procedure, sample handling, and calculation methods to ensure accuracy and consistency. These guidelines support uniform testing and reliable results in concrete quality assessment across India.
Advantages of the Vee Bee Consistometer Test
The following are the major benefits of the Vebe test:
- The Vee Bee Consistometer Test (VCT) is a practical method for assessing the workability of very stiff or dry concrete mixes, especially when the regular slump test cannot provide accurate results.
- It provides a quantitative measure of workability by recording the time (in seconds) required for the concrete to change shape under vibration, known as the Vee Bee seconds.
- The test provides direct results on the remoulding effort required to convert concrete from conical to cylindrical shape, indicating mobility and compactability.
- It is particularly useful for quality control of low-workability concretes in laboratory settings.
Limitations of the Vee Bee Consistometer Test
- The test apparatus is quite big and requires precise vibration control to avoid external interference, making it generally unsuitable for field use.
- It is mainly limited to low-slump concretes (typically below 50mm); for concrete with a higher slump, remoulding is so rapid that timing is impractical.
- Because of its size and additional requirements of electrical vibration equipment, it’s only suitable for lab tests, not for site testing.
On a final note, the Vee Bee Consistometer test is a simple yet effective laboratory technique for determining the workability of concrete. This test is primarily designed for dry concretes with a low water-to-cement ratio, for which normal slump tests cannot be performed. Although this test has its own limitations, it is considered essential for ensuring concrete quality. For professional construction services in Bengaluru that prioritise concrete testing and quality construction work, consider partnering with Brick & Bolt, who offer reliable construction solutions to realise your dream home.
Frequently Asked Questions
What is a vee bee consistometer test?
The Vee-Bee consistometer test is a laboratory testing method mainly used to check the time required for the concrete mix to get fully compacted; that is, the indication of workability.
What is the VB test used for?
The Vee-Bee (VB) test measures the workability of dry or stiff concrete mixes with a very low water-to-cement ratio. It is especially helpful when the slump test cannot be used because the concrete is too stiff to measure accurately.
What does the Vee Bee time indicate?
The Vee Bee time reflects the workability of the concrete; shorter times indicate higher workability. For example, times 0-3 seconds indicate high workability, while 10-20 seconds indicate very low workability.
Which IS code covers the Vee Bee Test procedure?
The test is standardized under IS 1199:1959 and its later revisions, which detail sampling and testing methods for fresh concrete workability assessment.
Who developed the Vee Bee Consistometer Test?
It was developed by V. Bahrner from Sweden.