The workability of concrete can be improved by:
Try it first: pick an option, then read the explanation.
Correct answer: B. More cement
Detailed Explanation: How More Cement Improves Workability
Why B (More cement) is correct: Cement paste is the lubricating medium in concrete. Increasing cement content (at constant w/c ratio) increases paste volume. More paste = thicker film on aggregate surfaces = better lubrication = improved workability. Options A (more sand) and C (more fine aggregate) increase total specific surface area, requiring more water to coat surfaces — this actually reduces workability at a given water content. Option D (finer coarse aggregate) also increases surface area and reduces workability.Effect of Each Option on Workability
| Change | Effect on Workability | Reason |
|---|---|---|
| More sand | Decreases | Higher surface area absorbs free water |
| More cement (at const. w/c) | Increases | More paste = better lubrication |
| More fine aggregate | Decreases | Higher surface area |
| Finer coarse aggregate | Decreases | More surface area per kg |
- More cement at constant w/c = more paste volume = better workability.
- In practice, plasticisers achieve workability improvement more economically than extra cement.