Compacting Factor Test

Compacting Factor Test

Definition:

• A Compacting Factor Test is used to measure the degree of workability of fresh concrete.

Instruments:

1. Upper Hopper: Initially holds the concrete.
2. Lower Hopper: Positioned below the upper hopper.
3. Cylinder (Mold): Collects the concrete after passing through the hoppers.
4. Tamping Rod: Used to eliminate air voids in concrete.

Procedure:

1. Fill Upper Hopper: Pour concrete into the upper hopper.
2. Release Concrete: Open the trap door to let concrete move into the lower hopper.
3. Release Again: Open the lower hopper's trap door for concrete to fall into the cylinder.
4. Strike Off: Level off the concrete in the cylinder to its full capacity.

Results:

• Weight of Full Concrete: Measure the weight of the concrete in the cylinder after filling.
• Weight of Partially Compacted Concrete: Take the weight of the concrete after the initial setup without any compaction.

Formulas:

• Compacting Factor (CF): CF = (Weight of Partially Compacted Concrete) / (Weight of Fully Compacted Concrete)

Key Points:

• The Compacting Factor Test is suited for concrete mixtures with low water-cement ratios.
• Higher Compacting Factor indicates better workability.
• The test provides an empirical value reflecting the ease with which concrete can be compacted.

Concepts:

• Workability: Refers to the ease of mixing, transporting, placing, and compacting concrete without segregation or bleeding.
• Segregation: The separation of different components of concrete.
• Bleeding: The accumulation of water appearing on the surface of concrete.

These notes give a detailed view of the process, instruments, and calculations involved in a Compacting Factor Test, providing a clear understanding of workability measurement in concrete.