Which of the following term is used to express the process of water coming out from the concrete and accumulate at the surface of concrete during compaction?
Correct Answer: D. Bleeding
📚 Detailed Explanation: Bleeding in Fresh Concrete
Bleeding is a form of segregation in which excess water rises to the surface of freshly placed and compacted concrete. It is driven by gravity — the heavier cement and aggregate particles settle downward, displacing the lighter water upward.
Why D (Bleeding) is correct: Bleeding is the specific technical term for upward water migration during and after compaction. Option A (Efflorescence) refers to white salt deposits on hardened concrete or masonry surfaces — a durability issue, not a fresh concrete phenomenon. Option B (Seepage) is water movement through a porous medium under hydraulic pressure. Option C (Permeability) is the ability of hardened concrete to transmit fluids under pressure.
Comparison of Related Terms
| Term | Definition | Stage |
|---|---|---|
| Bleeding | Water rises to surface during compaction | Fresh concrete |
| Segregation | Coarse aggregate separates from paste | Fresh concrete |
| Laitance | Weak layer of cement/water left by bleeding | Surface of set concrete |
| Efflorescence | White salt deposits on hardened surface | Hardened concrete |
Key Concepts for Students
- Bleeding is caused by high w/c ratio, fine cement, or smooth aggregates — reducing w/c is the primary remedy.
- Bleeding creates vertical capillary channels through which water-borne impurities can later seep, reducing durability.
- Laitance (the weak layer left by bleeding water) must be removed before placing the next concrete lift.