Regarding Bogue’s compounds in portland cement, which of the following statements is correct regarding their contribution to strength and heat of hydration? 1. C3S hydrates more rapidly than C2S and is responsible for the "initial" set and early strength within the first 7 days. 2. C3A reacts instantaneously with water, contributing the highest heat of hydration but providing the least long-term structural strength. 3. C4AF is primarily responsible for the resistance of cement against sulfate attack. Which of the statements given above are correct?
- A1 and 2 onlyCorrect
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3
Solution
Concept
Bogue's Compounds in Cement
Formula
N/A
Step-by-step solution
1. Evaluate Statement 1 (C3S) and Statement 2 (C3A), confirming both correctly describe rate of hydration, early strength, and heat of hydration. 2. Evaluate Statement 3 and note that low C3A content, not C4AF, governs resistance to sulfate attack. 3. Choose Option (a) as the correct answer containing statements 1 and 2 only.
Explanation
Statements 1 and 2 are correct because C3S reacts quickly to provide early strength within the first week, and C3A reacts instantly upon mixing with water, producing the maximum heat while contributing very little to structural strength. Statement 3 is incorrect because low C3A content (not C4AF) is mainly responsible for resistance against sulfate attack. Therefore, Option A (1 and 2 only) is the correct answer.
Shortcut
To easily remember Bogue's compounds and their key characteristics, use this simple quick-reference guide: - C3S (Speed & Seven): Rapid hydration giving early strength within the first 7 days - C2S (Slow & Secondary): Slow hydration providing long-term progressive strength - C3A (Active & Ardent): Instant reaction with the highest heat of hydration - C4AF (Feeble Ferrite): Contributes little to strength; low C3A (not C4AF) gives sulfate resistance
Common mistake
A common mistake is selecting option D by incorrectly assuming that C4AF is primarily responsible for resistance against sulfate attack. In reality, it is low C3A content that provides resistance to sulfate attack, while C4AF contributes minimally to strength and acts mainly as a flux during manufacturing.
Correct answer: A) 1 and 2 only