Due to segregation of well-mixed concrete, –
Correct Answer: A. the workability of concrete decreases
📚 Detailed Explanation: Effect of Segregation on Concrete Properties
Segregation is the separation of concrete ingredients — coarse aggregates tend to settle or roll away from the mortar matrix. Once segregated, concrete can no longer be considered properly workable, strong, or durable.
Why A (workability decreases) is correct: When coarse aggregates separate from the paste, the mortar portion becomes paste-rich but the coarse aggregate zone is paste-deficient. The segregated mix is no longer a uniform, flowable mass — its effective workability drops. Option B is wrong: segregation creates voids and reduces durability. Option C is wrong: segregated concrete is weaker (non-uniform bonding). Option D is wrong: segregation creates voids and increases permeability.
Consequences of Segregation
| Property | Effect of Segregation |
|---|---|
| Workability | Decreases (non-uniform mix) |
| Compressive strength | Decreases (weak zones) |
| Durability | Decreases (voids and cracks) |
| Permeability | Increases (more connected pores) |
- Segregation is caused by high w/c ratio, over-vibration, dropping concrete from excessive height, or poorly graded aggregates.
- Prevention: use proper w/c, well-graded aggregates, and correct vibration duration.