The test used to find out the workability of freshly mixed concrete by the consistometer apparatus is known as Vee Bee Test.
Principles of Vee Bee Test
Vee bee test is conducted at the laboratory. This test gives results based on the mobility and compatibility of the concrete.
In Simple Words,
- This test measures the relative effort & time that is required to convert the concrete mould from one shape to another.
- The effort taken to convert the mould from one shape to another is known as remoulding effort.
- The time that has been taken for the concrete to settle down in cylindrical shape is measured in seconds, which is known as vee bee seconds.
- This test is suitable for the concrete slump value lower than 50 mm. If it has more than 50 mm value, then the concrete settles quickly on the container pot, which is hard to measure in seconds.
Please watch the video and read the principles once again for a better understanding.
- Tamping rod 500 mm long & 20 mm dia.
- The vibrator table should be 380mm long & 260mm width, which rests on elastic support at height 305mm above floor level.
- The table should be mounted on a base which is equipped with an electrically operated vibrometer.
- The sheet metal cone should be 30 cm height, and the diameter should be 20 cm and 10 cm at the bottom and top, respectively.
- The graduated rod is fixed in a whirling arm. A glass disc is screwed at the end of the arm.
- The division scale records the slump cone value of concrete in centimeters.
Vee Bee Test Procedure
- Step 1 – Place the slump cone in the consistometer machine.
- Step 2 – Fill the cone with concrete in four layers.
- Step 3 – Each layer should be tamped 25 times by the tamping rod.
- Step 4 – Remove the excess concrete from the slump cone & level it.
- Step 5 – Now, rotate the glass disc, which is attached to the whirling arm and place it over the slump cone concrete level & measure the initial reading from the graduated rod.
- Step 6 – Rotate the glass disc to its original position. Then remove the slump cone slowly in a vertical direction. You can see the concrete slightly changed from its shape.
- Step 7 – Now again, rotate the glass disc and measure the final reading.
- Step 8 – Now turn on the electrical vibrator table & eventually switch on the stopwatch, continue the vibration until the concrete remoulded, and the surface of the concrete becomes horizontal.
- Step 9 – Once the concrete surfaces come horizontal in the cylindrical pot, stop the vibration & the watch.
- Step 10 – Record the time – Vee Bee Seconds.
- Slump value = Initial Reading on the graduated scale (a) – Final Reading on the graduated scale (b)
- Consistency of concrete is measured in Vee Bee Seconds
Workability Description Table
How it differs from other workability tests?
According to the concrete workability and time availability, each test has been listed below.
|#||Test Name||Suitable Workability||Performed @|
|1||Slump Test||High||Field / Lab|
|2||Kelly Ball Test||High||Field / Lab|
|4||Flow Table test||Low||Lab|
|5||Vee – bee test||Low & very low||Lab|