To study the workability of concrete


Compaction factor apparatus’ trowels, hand scoop (15.2 cm long), a rod of steel or other suitable material (1.6 cm diameter, 61 cm long rounded at one end ) and a balance.


Concrete mix (M15) is prepared as per mix design in the laboratory


(I)Place the concrete sample gently in the upper hopper to its brim using the hand scoop and level it.

(ii) Cover the cylinder

(iii) Open the trap door at the bottom of the upper hopper so that concrete fall in to the lower hopper .Push the concrete sticking on its sides gently with the road.

(iv) Open the trap door of the lower hopper and allow the concrete to fall in to the cylinder below

(v) Cut of the excess of concrete above the top level of cylinder using trowels and level it. (vi) Clean the outside of the cylinder.

(vii) Weight the cylinder with concrete to the nearest 10 g. This weight is known as the weight of partially compacted concrete (wi).

(viii) Empty the cylinder and then refill it with the same concrete mix in layers approximately 5cm deep, each layer being heavily rammed to obtain full compaction.

(ix) Level the top surface.

(x) Weigh the cylinder with fully compacted. This weight is known as the weight of fully compacted concrete (w2).

(xi) Find the weight of empty cylinder (W).


The test is sufficiently sensitive to enable difference in work ability arising from the initial process in the hydration of cement to be measured. Each test, there for should be carried out at a constant time interval after the mixing is completed, if strictly comparable results are to be obtained. Convenient time for releasing the concrete from the upper hopper has been found to be two minutes after the completion of mixing.


  1. The compaction factor is defined as the ratio of the weight of partially compacted concrete to the weight of fully compacted concrete. It shall normally to be stated to the nearest second decimal place.
  1. Compaction Factor= (W1-W2 / W2-W)


Compactio0n factor of the concrete =