Theory:

Workability is the ease with which concrete can be handled, deposited or placed and spread into its final location and compacted. It depends on the fluidity or wetness plasticity and cohesiveness and harshness of concrete. Workability to be adopted also depends on thickness of structural member where the concrete is to be placed. Thus for thin member more fluid concrete is required where for massive work a stiffer concrete can be used. In heavily and conjusted rainforce structure more workable of concrete required, so as to ensure no hollows remains. The test is based on the principle that the workability of concrete is reflected or indicated by its compaction by standard amount of workdone on it. By allowing it to fall under gravity through a standard height. In a standard cylinder the ratio of density of fully compacted concrete is called compacted factor.

                                           Density of partially / Compacted concrete
Compaction factor =     -------------------------------------------------------------
                                               Density of fully / Compacted concrete

Application:

The purpose of this test is to know the workability of fresh concrete. It is used while designing of concrete mix during trial mixes. The application of this test is ready to check uniformity of concrete. In the field by making regular test on concrete.

Items Required:

1. Compaction factors apparatus. The apparatus has two  hoppers cone below the other and the cylinder below the  lower hopper.
2.     Tamping rod.
3.     Weighing balance.
4.     Cement, sand, course aggregate, water.

Procedure:
  1. The internal surface of mould was clean and dryed.
  2. Prepare a concrete mix for testing workability.
  3. Placed the concrete into the upper hopper.
  4. Open the trapped door of the upper hopper, The concrete mixed full into the lower hopper.
  5. Open the trap clear of lower hopper so that the concrete was full into the cylinder below.
  6. Remove the excess concrete above the level of cylinder clean the outside of cylinder.
  7. When the concrete in the cylinder this weight of concrete was the weight of partially compacted concrete (w1).
  8.  Emptied the cylinder and refill with concrete in layer impacting each layer well.
  9. Find out the weight of concrete in fully compacted stage. This weight was of fully compacted concrete (w2).

Precaution:

1.     The cylinder should oiled correctly.
2.     The weight of the sample should taken accurately.
3.     The concrete mix should be mix as the given proportion.
4.   The mix should be fill in cylinder in layers and it should be tamped with tamping rod.

Observation:

1.     Weight of partially compacted concrete (w1)
2.     Weight of fully compacted concrete (w2)
3.     Volume of concrete V


      Diagram:


                                          Compaction Factor Apparatus


Calculation:

                                           w1/v
Compaction factor  =        ---------    =   w1/w2
                                           w2/v



SAMPLE  1:

Weight of partially compacted concrete = 21.2 Kg (w1)

Weight of fully compacted concrete = 23.3 Kg (w2)

Compaction Factor = w1 / w2  = 21.2 / 23.3 = 0.909

SAMPLE  2:

Weight of partially compacted concrete = 22.1 Kg (w1)

Weight of fully compacted concrete = 23.2 Kg (w2)

Compaction Factor = w1 / w2  = 22.1 / 23.2 = 0.953

Average of compaction factor = 0.909 + 0.953 / 2
                                                = 0.931  
                  
Conclusion:

As the compaction factor of the given sample of concrete is 0.931
It is consider as high workability.

Result:

Compaction factor of the given sample of concrete is 0.931