Low workability of concrete conforms to a slump of:
Correct Answer: A. 25-75 mm
📚 Detailed Explanation: Slump Range for Low Workability
Why A (25–75 mm) is correct: IS 456 / standard textbook classification:
• 0–25 mm: Very low workability
• 25–75 mm: Low workability
• 50–100 mm: Medium workability
• 75–150 mm: High workability
Options B (50–100) and C (75–100) fall in the medium range. Option D (100–150) is high workability. The correct low workability range is 25–75 mm.
• 0–25 mm: Very low workability
• 25–75 mm: Low workability
• 50–100 mm: Medium workability
• 75–150 mm: High workability
Options B (50–100) and C (75–100) fall in the medium range. Option D (100–150) is high workability. The correct low workability range is 25–75 mm.
Workability Classification by Slump
| Workability | Slump (mm) | Typical Use |
|---|---|---|
| Very low | 0–25 | Mass concrete, pavement (manual) |
| Low | 25–75 | Road slabs, lightly reinforced members |
| Medium | 50–100 | Normal RCC beams, slabs, columns |
| High | 75–150 | Heavily reinforced, pumped concrete |
- Low workability = 25–75 mm slump per IS 456.