What is Compaction Factor Test of Concrete Mix?


The compaction factor test is a workability test for concrete mix. It is used to determine the workability of concrete. The compacting factor test is designed primarily for using in the laboratory but it can also be used in the construction field.

Compaction factor test is more precise and sensitive than the slump test and it is particularly useful for concrete mixes of very low workability as are normally used when concrete is to be compacted by vibration. Such concrete may be consistently fail to slump. Compaction factor test was developed by Road Research Laboratory in United Kingdom.


The compaction factor is expressed as the ratio of the weight of partially compacted concrete to the weight of fully compacted concrete.

Workability of Concrete by Compaction Factor Test Lab Report


Compaction Factor Test of Concrete: Procedure Lab Report pdf as per IS Code: 1199-1959


Hi friends, you are welcomed in the world of Civil Allied Gyan. "Read here definition, apparatus, IS code, test procedure, formula, result and lab report for compaction factor test of concrete to find workability."

 

By the help of this you can easily find the consistency or workability of concrete by compaction factor test.



  • Compaction factor apparatus
  • Weighing balance
  • Tamping rod
  • Trowel
  • Scoop about 150 mm long
  • Tamper (16 mm in diameter and 600 mm length)
  • Ruler
  • Containers and tools for mixing or concrete mixer etc.

Workability of Concrete by Compaction Factor Test Lab Report


What is Compaction Factor Apparatus?

Compacting factor apparatus is used in workability test of concrete. It consists of two conical hoppers mounted above a cylindrical mould and fixed to a stand one above the other. The hoppers are provided with trap doors at the bottom. The dimensions of various parts are given below.

1. Upper Hopper
Dimensions in cm.
Top internal dia.
25.4
Bottom
12.7
Internal height
27.9
2. Lower Hopper
Dimensions in cm.
Top internal dia.
22.9
Bottom
12.7
Internal height
22.9
3. Cylinder
Dimension in cm.
Internal Diameter
15.2
Internal Height
30.5

Note: (I) Distance between bottom of upper hopper and top of lower hopper is 20.3 cm. (II) Distance between bottom of lower hopper and top of cylinder is 20.3 cm.


  • IS: 1199-1959, Methods for sampling and analysis of concrete mix
  • IS: 5515-1983, Specification for compressive factor apparatus


  1. Preparation of Specimens:- Prepare four mixes with W/C ratios 0.4, 0.5, 0.55, 0.6 and 0.65. For each mix take 5 kg of fine aggregate, 10 kg of coarse aggregate and 2.5 kg of cement.
  2. Grease the inner surface of the hoppers and the cylinder and fasten the hopper doors.
  3. Weigh the empty cylinder accurately (W Kg) and fix the cylinder on the base with nuts and bolts.
  4. Mix coarse and fine aggregates and cement dry until the mixture gets uniform in colour and then add water mix until concrete appears to be homogeneous.
  5. Fill the sample of concrete to be tested in upper hopper gently with trowel without compacting. The hopper is filled level with its brim.
  6. Now open the trap door of the upper hopper and allow the concrete mixes to fall into the lower hopper bringing the concrete into standard compaction.
  7. If concrete has a tendency to stick to the sides of the hopper, the concrete should be slowly pushed down by inserting the tamping rod into the concrete mix.
  8. Immediately after the concrete comes to door of the lower hopper, open the trap door of the lower hopper and allow the concrete mixes to fall into the cylinder, bringing the concrete into standard compaction.
  9. Cut off the excess of concrete above the top of the cylinder and make level with trowels. Wipe the outside of cylinder cleanly.
  10. Find the weight of cylinder i.e. cylinder filled with partially compacted concrete (W Kg).
  11. Refill the cylinder with the same sample of concrete mixes in approx. 4 layers, tamping each layer with tamping rod for 25 times in order to obtain full compaction of concrete mix.
  12. The top of fully compacted concrete mix should be carefully struck off level with top cylinder. The outside of the cylinder is wiped a clean.
  13. Weigh the cylinder filled with fully compacted concrete (W Kg).
  14. Repeat the procedure different-different for different a trowel.



Observations and Calculations:-

Weight of cylinder = W(in kg)
Weight of cylinder + partially compacted concrete = W
Weight of Partially compacted concrete = W‒W
Weight of cylinder + fully compacted concrete = W
Weight of fully compacted concrete = WW



Table:-

Workability of Concrete by Compaction Factor Test Lab Report


Formula for compaction factor test of concrete:-

Workability of Concrete by Compaction Factor Test Lab Report

Results:-
Compaction factor is = ……………. or
Maximum workability of concrete is occurring at a water/cement (W/C) ratio of ………….



Report:-

The compaction factor of concrete is reported as the ratio of the weight of partially compacted concrete to the weight of fully compacted concrete. The value of compaction factor shall normally be stated to the nearest second decimal place.



*According to IS 456, the degree of workability in classified as follows:
Degree of Workability
Compacting Factor
Very Low
0.75 to 0.8
Low
0.8 to 0.85
Medium
0.85 to 0.92
High
0.92 & above


*Relation between workability, compaction factor and slump:-
Workability
Compaction Factor
Slump (mm)
Very Low
0.78
0 - 25
Low
0.85
25 - 50
Medium
0.92
50 - 100
High
0.95
100 - 175


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