How many hoppers are in compaction factor test of concrete?
Correct Answer: C. 2
📚 Detailed Explanation: Compacting Factor Apparatus — 2 Hoppers
Why C (2) is correct: The apparatus consists of three parts stacked vertically: Upper conical hopper (larger) → Lower conical hopper (slightly smaller) → Cylinder at the bottom. Concrete is placed in the upper hopper, released into the lower hopper, then released into the cylinder. The two-stage fall provides a controlled, reproducible energy input for partial compaction. The mass of partially compacted concrete in the cylinder is then compared to fully compacted concrete mass.
Compacting Factor Apparatus Components
| Component | Position | Key Dimension |
|---|---|---|
| Upper hopper (conical) | Top | Top ø 25.4 cm, Bottom ø 12.7 cm |
| Lower hopper (conical) | Middle | Top ø 22.9 cm, Bottom ø 12.7 cm |
| Cylinder | Bottom | ø 15.2 cm × 30.5 cm |
- 2 hoppers + 1 cylinder = 3 total components, 2 are hoppers.
- The trapdoors of each hopper are released one at a time to control the fall height.