W1 and W2 are the weights of a cylinder partially compacted and fully compacted. If the compaction factor (W1/W2) is 0.95, the workability of concrete is:
Correct Answer: D. High
📚 Detailed Explanation: Compaction Factor 0.95 = High Workability
Why D (High) is correct: The Compaction Factor (CF) is defined as:
CF = W1 / W2
where W1 = weight of partially compacted concrete in the cylinder (under gravity, via the two hoppers), and W2 = weight of fully compacted concrete in the same cylinder (manually compacted to maximum density).
CF = W1 / W2
where W1 = weight of partially compacted concrete in the cylinder (under gravity, via the two hoppers), and W2 = weight of fully compacted concrete in the same cylinder (manually compacted to maximum density).
CF = 0.95 means the concrete under gravity alone achieves 95% of the fully compacted weight — indicating it is very fluid and needs minimal compaction effort. Per IS 7320 / IS 5515:
• CF <0.75: Very low
• CF 0.75–0.85: Low
• CF 0.85–0.92: Medium
• CF >0.92 (here: 0.95): High workability
Compaction Factor Classification
| CF Value | Workability |
|---|---|
| <0.75 | Very low |
| 0.75–0.85 | Low |
| 0.85–0.92 | Medium |
| >0.92 (0.95) | High |
- CF = W1 / W2 = 0.95 > 0.92 → High workability.
- CF approaches 1.0 for very fluid / self-compacting concrete (SCC); stiff mixes give CF around 0.7–0.8.