Match List-I (Type of cement) with List-II (Characteristics) and select the correct answer using the codes given below the lists.
| List-I | List-II |
|---|---|
| a.Air entering Portland cement | 1.Sustainable for very large structures |
| b.Low heat Portland cement | 2.Unsuitable for very large masses of concrete |
| c.Hydrophobic Portland cement | 3.Greater resistance to frost attack |
| d.Rapid hardening Portland cement | 4.Safe storage under unfavourable conditions of humidity |
Codes:
- Aa – 4, b – 2, c – 1, d – 3
- Ba – 3, b – 4, c – 1, d – 2
- Ca – 3, b – 1, c – 4, d – 2Correct
- Da – 4, b – 1, c – 2, d – 3
Solution
Concept
Types and Properties of Portland Cement
Formula
No
Step-by-step solution
1. Match Air-entraining Portland cement with resistance to frost attack (a - 3). 2. Match Low heat Portland cement with suitability for large structures (b - 1). 3. Match Hydrophobic Portland cement with safe storage under humid conditions (c - 4). 4. Match Rapid hardening Portland cement with unsuitability for large masses of concrete (d - 2).
Explanation
Option C (a-3, b-1, c-4, d-2) is correct because:1. Air-entraining Portland cement creates microscopic air bubbles in concrete, which provides greater resistance to frost attack and freeze-thaw cycles. 2. Low heat Portland cement produces less heat during hydration, making it suitable and sustainable for mass concrete structures like dams to prevent thermal cracking. 3. Hydrophobic Portland cement is treated with water-repellent chemicals, allowing safe storage in humid environments without absorbing moisture before mixing. 4. Rapid hardening Portland cement releases heat very quickly, making it unsuitable for large, thick masses of concrete due to the risk of thermal cracking.
Shortcut
Associate key terms: - Air = Frost (air bubbles protect against freezing) - Low Heat = Large Structures (prevents thermal cracking in mass concrete) - Hydrophobic = Humidity (water-repellent for wet storage) - Rapid Hardening = Unsuitable for Large Masses (generates excessive heat)
Common mistake
A common mistake is confusing low heat cement with rapid hardening cement regarding their suitability for mass concrete structures, leading students to incorrectly swap options 1 and 2.
Correct answer: C) a – 3, b – 1, c – 4, d – 2