What should be done to ensure constant moisture content in aggregates?
Correct Answer: D. All of these
📚 Detailed Explanation: Ensuring Uniform Moisture in Aggregate Stockpiles
Consistent moisture content in aggregate stockpiles is essential for accurate batching, because any deviation from the assumed moisture level changes the effective water-cement ratio and can significantly affect concrete workability and strength. Good stockpile management prevents moisture variations that would require constant re-testing and adjustment.
Why D (All of these) is correct: All three practices work together: (1) A large pile area minimises the proportion of saturated material at the base (where drainage water accumulates), making the moisture distribution more uniform. (2) Height ≤1.50 m limits the depth that water must travel to drain, again preventing a wet base and dry top. (3) Leaving for 24 hours allows drainage to reach equilibrium, so the moisture content stabilises before the material is used.
Good Aggregate Stockpile Practices
| Practice | Reason |
|---|---|
| Large pile area (spread out) | Reduces moisture gradient from base to surface |
| Height ≤1.50 m | Allows complete drainage through the pile depth |
| 24-hour standing time | Moisture reaches equilibrium before sampling/use |
| Separate stockpiles by size | Prevents segregation and grading variation |
Key Concepts for Students
- IS 4082 gives recommendations for storage of construction materials, including aggregate stockpiling requirements.
- Moisture correction for aggregates must always be made in mix design: measure moisture content of each aggregate batch and adjust batch water accordingly.
- Coarse and fine aggregates should be stockpiled separately to avoid contamination and maintain their individual grading properties.