Vee bee

Expt No:
Date:
VEE-BEE TEST
AIM:
To determine the workability of concrete using Vee-Bee apparatus.
DEFINITION:
This is a good laboratory test to measure indirectly the workability of
concrete.
The test consists of a vibrating table, a metal pot & a standard iron rod.
APPARATUS:
The apparatus consists of vibrating table, metal pot, a sheet metal cone and
standard iron rod.
PRINCIPLE:
The test is based on the principle of measuring the energy required o fill &
compact fresh concrete in a mould. The amount of effort required to change the
shape of
a sample of concrete from one form to another gives the workability of concrete.
The tie
necessary for the remoulding of concrete, when placed over a vibrating table &
vibrated
is a measure of the input energy required for compaction. This is expressed in Vee-
Bee
seconds. Hence workability is expressed as the time necessary for the remoulding
to be complete (i.e., in Vee-Bee seconds).
During the remoulding, some compaction takes place & the volume of
concrete gets reduced. Taking into consideration the decrease of volume due to the
compaction, the Vee-Bee second is multiplied by the ratio of volume of concrete
after & before the vibrations.
TEST SETUP:
In the Vee-Bee test, the time taken to transform the concrete from conical
shape to cylindrical shape is measured. A standard slump cone is placed in a

OBSERVATIONS AND CALCULATIONS:
Mix ratio =
Height of slump cone, h =
Top radius of slump cone,r1 =
Bottom radius of slump cone,r2 =
Height of vibration cylinder, H =
Radius of vibration cylinder, r =
Volume of concrete before vibration, V1 = (πh(r2
3
-r1
3
))/(3(r2-r1)
W/C
ratio
Slump
Vee-Bee
Seconds
(s)
Height of
cone after
vibration, h2
(cm)
Volume of cone
after vibration,
V2= πr2
h2
(cm3
)
Volume ratio
(V2/V1)
Corrected
Vee-Bee
seconds
(s)

cylinder of standard size, the cylinder being mounted rigidly on a vibrating table.
Freshly prepared concrete is placed inside the slump cone in four layers & is
compacted by tamping 25 times using a standard tamping rod. A sliding glass disc
gives the height of concrete at different levels. After removing the slump cone, the
substance of concrete can be noted using the glass plate rider. This gives the
slump value of concrete.
Vibration is given to the table till the remoulding is complete i.e., when the
glass plate rider is completely covered with concrete & all cavities in the surface of
concrete have disappeared. Stopwatch operated at the start of vibration gives the
Vee-Bee seconds. The time required for the remoulding to be complete is noted as
the workability of the mix. For different water / cement ratios, the test is repeated.
A graph drawn between slump & Vee-Bee seconds can be used to study the
behaviour of concrete.
PROCEDURE:
1. Clean the slump cone & cylinder well.
2. Prepare the concrete of a nominal mix with an initial water / cement ratio =
0.5.
3. Place the slump cone inside the cylinder & fill it as described earlier in
layers.
4. Remove the slump cone & note the subsidence of concrete with the help of
glass plate rider.
5. Vibrate the table till the concrete is completely remoulded. When the
vibration is started, start the stopwatch.
6. Note the time taken for the complete transformation from conical shape to
cylindrical form.
7. Repeat the test using different water / cement ratio such as 0.6, 0.7, 0.8 etc.
8. Draw a graph taking Vee-Bee seconds along X-axis & slump along Y-axis.

RESULT:
Workability of concrete as expressed in terms of Vee-Bee seconds for 1:2:4
mix ratio
at water / cement ratio 0.6 = s
Workability of concrete as expressed in terms of Vee-Bee seconds for
1:2:4mix ratio at water-cement ratio, 0.6 = s.

Vee bee

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