Identify the wrong statement regarding bulking of sand:
Correct Answer: C. Bulking considered in weight batching
📚 Detailed Explanation: Bulking is Irrelevant to Weight Batching
Why C is WRONG (= the answer): Bulking is a volume phenomenon — the apparent volume of moist sand increases. But the mass of a given amount of sand is completely unaffected by moisture content (water adds mass, but for small surface moisture amounts this is negligible for practical purposes). In weight batching, you weigh out the required mass of sand — whether the sand is dry or moist, 1 kg is 1 kg. No bulking correction is needed.
Bulking correction is ONLY needed in volume batching, where you measure by gauge box volume and the bulked sand fills a larger volume than the dry sand.
Checking All Statements
| Statement | Verdict | Reason |
|---|---|---|
| A. Bulking can go up to 40% | Correct | For very fine sand at peak moisture, bulking can reach 35–40% |
| B. Maximum bulking at 4.6% moisture | Correct | Peak typically at 4–6%; 4.6% is within this range |
| C. Bulking considered in weight batching | WRONG | Weight batching uses mass; mass unaffected by bulking |
| D. Bulking due to free moisture film | Correct | Correct mechanism: surface water film → surface tension → bulking |
- Bulking correction: required for volume batching, NOT needed for weight batching.
- This is the key advantage of weight batching over volume batching.