What is the compaction factor test?
The test used to find out the compaction factor (external force required) for a low workability concrete is known as the compaction factor test. It is conducted in the laboratory.
The compaction factor is the ratio between partially compacted to fully compacted concrete.
The test performed as per IS code 1199, and it gives accurate results compared to slump cone tests because low workability concrete may fail by doing slump tests.
The compaction factor test is performed to find out the workability of concrete where the coarse aggregate size does not exceed 38mm.
The compaction factor test can be used in both field & lab based on the circumstances.
The detailed dimension of the compaction factor testing machine components has been given below.
SI | Components | Dimension in mm |
1 | Upper Hopper A | |
Top internal diameter | 254 | |
Bottom internal diameter | 127 | |
Internal height | 279 | |
2 | Lower Hopper B | |
Top internal diameter | 229 | |
Bottom internal diameter | 127 | |
Internal height | 229 | |
3 | Cylinder C | |
Internal diameter | 152 | |
Internal height | 305 | |
4 | Distance between bottom of the upper hopper and top of the lower hopper | 203 |
5 | Distance between bottom of lower hopper and top of the cylinder | 203 |
Video Courtesy – MOBILE TUTOR
Compaction Factor (CF) = Partially compacted Concrete Weight /Fully compacted Concrete Weight
Partially compacted concrete weight Wp = W2 – W1
Fully compacted Concrete Weight Wf = W3 – W1
Compaction factor CF = Wp/Wf
The compaction factor value should be between the range of 0.7 to 0.95. Recommended compaction factor value is given below for different concrete workability.
Degree of Workability | Compaction Factor |
Very Low | 0.78 |
Low | 0.85 |
Medium | 0.92 |
High | 0.95 |
# | Description | Sample 1 | Sample 2 | Sample 3 |
1 | Weight of Empty Cylinder (W1) | |||
2 | Weight of Empty Cylinder + Free Fall Concrete(W2) | |||
3 | Weight of Empty Cylinder + Hand Compacted Concrete (W3) | |||
4 | Weight of Partially Compacted Concrete(WPÂ = W2Â – W1) | |||
5 | Weight of Fully Compacted Concrete(WFÂ = W3Â – W1) | |||
6 | Compaction Factor = WP/ WF |
Which one is the best test to determine the workability of concrete? Slump test or compacting factor?
If accurate results are required then the compaction factor test is best, else do the workability test by slump cone method because it is easy to do in the field.
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