Compacting factor of fresh concrete is done to determine the workability of fresh concrete by compacting factor test as per IS: 1199 – 1959.
Object: To determine the workability of concrete using compaction factor test.
Equipments Required for Compaction Factor Test: Compaction factor apparatus/machine, weighing balance, mixing tray.
Sampling of Materials for Slump Test: A concrete mix (M15 or other) by weight with suitable water/ cement ratio is prepaid in the laboratory.
Procedure:
(i) Oil the inner sides of the top and bottom cone frustum.
(ii)
Prepare a M15 concrete mix (1:2:4) using a
water content of about 0.4- 0.6 by weight of cement.
(iii)
Fill the top cone frustum with
the fresh mix of concrete and then open the gate and let the concrete fall on
the second frustum.
(iv)
Open the gate of second frustum
and let it fall on the cylinder to fill up to top of cylinder. (v) Measure the
weight of the cylinder filled with the concrete(partially compacted) and then
empty this.
(v)
Again fill the cylinder with the same sample
of the concrete but this time, do the compaction using the mechanical vibrator
to do the compaction.
(vi)
Again measure the weight of the cylinder
filled with the concrete(Fully compacted). (viii) Clean all the apparatus and
put them at their places as before.
Calculations:
Let weight of the empty cylinder = W1
Let weight of the cylinder with the partially compacted concrete = W2
Let weight of the fully compacted (Using mechanical vibrator) concrete with cylinder = W3
Compaction Factor = Weight of the partially compacted concrete/ Weight of the fully compacted concrete i.e,
Compaction factor = (W2-W1)/ (W3-W1)
Result: The compaction factor of the given fresh concrete mix is .....
(Note: Relation between the compaction factor and work-ability is that higher the compaction factor higher is the work-ability. Theoretical maximum value of the compaction factor can be 0.96 to 1.0