This is a site test to determine the consistency or workability of concrete and is conducted in the lab or on-site. Nowadays, this test is commonly replaced by the Slump Test to determine the workability of green concrete. The procedure of this test in brief is as follows;
1. Ensure the apparatus and associated equipment are clean before the test and free from hardened concrete and superfluous water.
2. Weigh the bottom cylinder to the nearest 10gm, put it back on the stand and cover it up with a pair of floats.
3. Gently fill the upper hopper with the sampled concrete to the level of the rim with the use of a scoop.
4. Immediately open the trap door of the upper hopper and allow the sampled concrete to fall into the middle hopper.
5. Remove the floats on top of the bottom cylinder and open the trap door of the middle hopper, allowing the sampled concrete to fall into the bottom cylinder.
6. Remove the surplus concrete above the top of the bottom cylinder by holding a float in each hand and moving towards each other to cut off the concrete across the top of the cylinder.
7. Wipe clean the outside of the cylinder of concrete and weigh to the nearest 10gm.
8. Subtract the weight of the empty cylinder from the weight of the cylinder plus concrete to obtain the weight of partially compacted concrete.
9. Remove the concrete from the cylinder and refill it with sampled concrete in layers.
10. Compact each layer thoroughly with the standard Compacting Bar to achieve full compaction.
11. Float off the surplus concrete to the top of the cylinder and wipe it clean.
12. Weigh the cylinder to the nearest 10gm and subtract the weight of the empty cylinder from the weight of the cylinder plus concrete to obtain the weight of fully compacted concrete.
13. The compacting factor ( CF ) = ( weight of partially compacted concrete ) divided by ( weight of fully compacted concrete ).