The value of Poisson's ratio of concrete lies approximately in the range:
Try it first: pick an option, then read the explanation.
Correct answer: C. 0.15 to 0.2
Asked in SSC JE 11/12/2020 (Evening)
Detailed Explanation
Poisson's ratio is different for each material. Brittle materials such as concrete have lower values than ductile metals.
Why “0.15 to 0.2” Is Correct
For concrete, μ is about 0.15 to 0.2. IS 456 suggests 0.2 for design calculations.
| Material | Poisson's ratio μ |
|---|---|
| Cork | ≈ 0 |
| Concrete | 0.15 – 0.20 |
| Cast iron | 0.21 – 0.26 |
| Steel | 0.27 – 0.30 |
| Copper | ≈ 0.33 |
| Rubber | 0.45 – 0.50 |
For isotropic materials μ cannot exceed 0.5; above that the volume would decrease under tension.
Why the Other Options Are Wrong
- A. 0.4 to 0.47: 0.4–0.47 is typical of rubber-like or very soft materials.
- B. 0.31 to 0.35: 0.31–0.35 suits metals like copper and aluminium.
- D. 0.25 to 0.3: 0.25–0.3 is typical of steel and cast iron.
Key Point
Concrete μ ≈ 0.15–0.2; steel ≈ 0.3.
Key Concepts for Students
- μ of concrete rises near failure as micro-cracks open.
- Cork has μ ≈ 0, which suits bottle stoppers.
- Soils: 0.2–0.5 depending on type and saturation.
Practice more: this is question 12 in Stress and Strain MCQs – Part 1. Try the whole set and check every answer instantly.