compaction factor test

Compaction Factor Test | Compaction Factor Test Procedure | Compaction Factor Apparatus5 min read

Compaction Factor Test

The compaction factor is defined as the ratio of the mass of compacted concrete in the compaction factor apparatus to the mass of fully compacted concrete.

The compaction factor test is carried out to measure the degree of workability of fresh concrete with regard to the internal energy required for compacting concrete thoroughly.

The compacting factor test is used to find out the low workability of concrete. it is a fact that the slump cone test of concrete is not given accurate results for the low workability of concrete when the slump is <50mm.

This test is more precise than the slump test but it is less common. The size of the apparatus makes it difficult to conduct the test in the field. The compaction factor test was developed by Road Research Laboratory in the United Kingdom. 

Read More: Slump Test – Type Of Slump & Test Method

Test of Concrete

Following are different concrete test,

  1. Rebound Hammer Test
  2. Tensile Strength Test of Concrete
  3. Ultrasonic Pulse Velocity Test on Concrete
  4. Concrete Cube Test

Compaction Factor Apparatus

As per IS1199:1999 Compaction factor test apparatus consists of,

 1) Two conical hoppers and a bottom cylinder which is arranged as shown in below fig.

2) Steel rod of 1.6 cm Diameter with a length of 61cm is used to tamp the concrete

3) Weight balance is used to weight the concrete.

compaction factor test
Compaction Factor Test

Compaction Factor Test Procedure

  1. The sample of concrete to be tested shall be placed gently in the upper hopper, using the hand scoop. 
  2. The hopper shall be filled level with its brim and the trap-door shall be opened so that the concrete falls into the lower hopper.
  3. Certain mixes have a tendency to stick in one or both of the hoppers. If this occurs, the concrete may be helped by pushing the rod gently into the concrete from the top.
  4. Immediately after the concrete has come to rest, the cylinder shall be uncovered, the trap-door of the lower hopper opened, and the concrete allowed falling into the cylinder. 
  5. The excess of concrete remaining above the level of the top of the cylinder shall then be cut off by holding a trowel.
  6. Weight the cylinder with concrete to the nearest 10 g. This weight is known as the weight of partially compacted concrete (W1).
  7. Empty the cylinder and then refill it with the same concrete mix in layers approximately 5 cm deep, each layer being heavily rammed to obtain full compaction.
  8. Level the top surface.
  9. Weigh the cylinder with fully compacted. This weight is known as the weight of fully compacted concrete (W2).
  10. Find the weight of the empty cylinder (W).

Read More: Tensile Strength Of Concrete – Test & Result


Observation Table

Sr. No.DescriptionSample 1Sample 2Sample 3
1Weight of Empty Cylinder (W1)   
2Wt. of Empty Cylinder + Free Fall Concrete(W2)   
3Wt. of Empty Cylinder + Hand Compacted Concrete (W3)   
4Wt. of partially Compacted Concrete(Wp = W2 – W1)   
5Weight of Fully or Proper Compacted Concrete (Wf = W3 – W1)   
6Compaction Factor = Wp/Wf   

Calculation of Compaction Factor Value

Compaction factor = Weight of Partially Compacted Concrete(Wp) / Weight of Fully Compacted Concrete(Wf)


Result

1. Compaction Factor of Concrete is found out to be =

2. The vertical difference between the top of the mould and the displaced original center of the top surface of specimen…………mm.

WorkabilityCompaction Factor
Very Low0.78
Low0.85
Medium0.92
High0.95

Why Compaction Factor Test if More Important than Slump Test for Workability of Concrete

Generally, the Slump Test is used to determine workability on the field, But it is not effective when the value of slump is lower than 50mm. Low workability concrete is used in mass concreting of foundations and light reinforced structures. In such a situation the compaction factor test is more suitable. Moreover, the compaction test gives more accurate results as compared to the slump test.


Relation Between Slump Test Result and Compaction Factor Test Result

WorkabilitySlump in mmCompaction Factor
Very Stiff0.70
Stiff0 to 250.75
Stiff Plastic25 to 500.85
Plastic75 to 1000.90
Flowing150 to 1750.95

FAQs: Compaction Factor Test

What is compaction factor test?

The compaction factor test is carried out to measure the degree of workability of fresh concrete with regard to the internal energy required for compacting concrete thoroughly. The compaction factor is defined as the ratio of the mass of compacted concrete in the compaction factor apparatus to the mass of fully compacted concrete.

Why compaction factor test is done?

The compaction factor test is carried out to measure the degree of workability of fresh concrete with regard to the internal energy required for compacting concrete thoroughly. The compacting factor test is used to find out the low workability of concrete.

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