- IS: 1199 -1959 (5.2).
- Compaction factor is defined as the ratio of the weight of partially compacted concrete to the weight of fully compacted concrete.
- Compaction factor apparatus
- Platform scale 100 kg capacity and sensitivity 10 grams
- Hand Scoop
- Vibrating Table
- Determine the initial weight (W1) of the cylinder.
- Place the sample of concrete gently in the upper hopper, using the hand scoop
- Fill the hopper in level with its brim.
- Open the trap door so that the concrete falls into the lower hopper.
- Certain mixes have a tendency to stick in one or both the hoppers.
- If this occurs, help the concrete through bypassing the rod gently into the concrete from the top.
- During the process cover the cylinder by the trowels.
- Uncover the cylinder immediately after the concrete has come to rest.
- Open the trap door of the lower hopper and allow the concrete to fall into the cylinder
- Remove the excess concrete above the level of the cylinder by holding a trowel in each hand with the plane of the blades horizontal, and moving them simultaneously one from each side across the top of the cylinder, at the same time, keeping them pressed on the edge of the cylinder.
- Wipe the outside of the cylinder and weigh (W2).
- Determine the net weight of the concrete in the cylinder (W2 – W1).
- This weight is known as the weight of partially compacted concrete.
- Refill the cylinder with the concrete from the same sample in layers approximately 5 cms deep, ram heavily or preferably vibrate so as to obtain full compaction.
- Carefully level the top surface.
- Wipe the outside of the cylinder and weight to the nearest 10gms (W3).
- Determine the net weight of the concrete in the cylinder (W3 – W1).
- This weight is known as the weight of fully compacted concrete.
Compaction Factor = ————-
- Report the result obtained to the nearest second decimal.
- This test is sufficiently sensitive to enable differences in workability from the initial process in the hydration of the cement to be measured.
- Therefore each test shall be carried out at a constant time interval after mixing is completed.
- A convenient time for releasing the concrete from the upper hopper has been found two minutes after the completion of mixing.
DETERMINATION OF COMPACTION FACTOR
|Description||Units||Trail I||Trail 2||Trail 3||Average|
|Grade of concrete||–|
|Weight of empty cylinder (W1)||gms|
|Weight of cylinder + concrete ( partially compacted) (W2)||gms|
|Weight of cylinder + concrete (fully compacted)(W3)||gms|
|Weight of partially compacted concrete (W2-W1)||gms|
|Weight of fully compacted concrete (W3- W1)||gms|
Compaction factor = ————