COMPACTION FACTOR TEST
Procedure
After preparation of the concrete mix, with the help of a trowel or hand scoop, place the concrete in the upper hopper upto its brim and level it properly, then cover the cylinder.
Open the trapdoor to allow the concrete falling freely in the lower hopper, a rod can be used to stick off concrete from the internal surface if present.
Now, after concrete gets collected in lower hopper, open the trapdoor to allow the concrete get collected in the underlying cylinder. Trim off any excess concrete from cylinder and then record the 'weight of partially compacted concrete' using weighing balance (empty cylinder weight already being tared) as W1.
Now, empty the cylinder and fill it with concrete in layers 5 cm deep, provided each layer must be compacted with 25 strokes of tamping rod or fully compacted using a needle vibrator.
Level off the excess concrete and record the 'weight of fully compacted concrete' using weighing balance (weight of empty cylinder already being tared) as W2.
Calculation of Compaction Factor
Compaction Factor = Weight of partially compacted concrete / Weight of fully compacted concrete
Compaction Factor = W1 / W2
Interpretation of Result
| Compaction Factor | Degree of Workability | Applications |
|---|---|---|
| 0.78 – 0.80 | Very Low | Vibrated concrete for roads |
| 0.80 – 0.85 | Low | Mass Concreting |
| 0.85 – 0.92 | Medium | RCC |
| 0.92 – 1.00 | High | Highly Reinforced Concrete |
Advantages
This test has certain advantages as it is relatively simple and easy to perform requiring less expertise, also this test helps in assessing the uniformity and compatibility of concrete, ensuring that it meets the required standards, moreover it provides a measure for workability of concrete, allowing for adjustments in mix design to achieve desired consistency as per its application.
Disadvantages
This test has limited applicability as it is primarily suitable for assessing the workability of low to medium slump values, sometimes this test proves out to be inconvenient in the time sensitive construction projects scenarios.