Which of the following options explain the effect of cold weather on concrete? (i)Delay in setting and hardening (ii)Freezing of concrete at early age (iii)Alternate Freezing and Thawing
- AOnly (i)
- B(i), (ii), and (iii)Correct
- CBoth (i) and (ii)
- DBoth (ii) and (iii)
Solution
Concept
Cold weather slows hydration of cement. Water in fresh concrete can freeze, and later the concrete can face repeated freezing and thawing.
Step-by-step solution
1. Low temperature slows cement hydration, so setting and hardening are delayed. Statement (i) is true. 2. Water in young concrete can freeze and expand, which damages it. Statement (ii) is true. 3. In cold regions, hardened concrete faces alternate freezing and thawing cycles, which cause scaling and cracking. Statement (iii) is true. 4. All three are correct, so the answer is option (B).
Explanation
Cold weather affects concrete in three ways: it delays setting and hardening, it can freeze fresh concrete at an early age, and it causes damage from alternate freezing and thawing. All three effects are given in standard textbooks (for example, M.S. Shetty).
Why the other options are wrong
(A), (C) and (D) each leave out at least one true effect. All three statements are correct.
Shortcut
Cold weather gives slow setting, early freezing and freeze-thaw cycles. All three are true.
Common mistake
Students leave out freeze-thaw, thinking it is only a durability problem and not a cold weather effect.
Correct answer: B) (i), (ii), and (iii)