Which of the following statements are false? i. Well-graded aggregates are less workable ii. Angular and flaky aggregates are less workable iii. Smoother the surface of aggregates, higher the workability
- AOnly (i)Correct
- BOnly (i) and (ii)
- COnly (ii) and (iii)
- D(i), (ii) and (iii)
Solution
Concept
Aggregate characteristics affecting concrete workability
Formula
NONE
Step-by-step solution
1. Aggregate workability depends on surface texture, shape, and particle size distribution. 2. Smooth surfaces improve workability, whereas angular shapes increase friction. Answer: A
Explanation
Well-graded aggregates contain particles of various sizes, which reduces void ratio and requires less water paste, thereby improving workability rather than decreasing it. Statements ii and iii are true because angular or flaky shapes increase friction, whereas smooth surfaces lower friction and increase workability. Thus, statement i is the only false statement, making option A correct.
Why the other options are wrong
C) Options (ii) and (iii) omit statement (i) which is also false according to the key.
Shortcut
Well-graded aggregates increase workability (false statement i): well-graded = better flow.
Common mistake
Confusing which statements are false versus true and assuming angular or flaky aggregates increase workability.
Correct answer: A) Only (i)