Air entraining cement is used principally to improve the resistance of concrete to:
A{'text': 'Freezing and thawing cycles', 'label': 'A'}
B{'text': 'Sulphate attack from soils', 'label': 'B'}
C{'text': 'Alkali-aggregate reaction', 'label': 'C'}
D{'text': 'Drying shrinkage cracks', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': 'Freezing and thawing cycles', 'label': 'A'}
1. §1.8.3 says the entrained 'tiny, discrete, non-coalescing air bubbles' modify hardened concrete 'with respect to its resistance to frost action,' and the Uses section directly states: 'Air entrained cement is ideal for use in structures subjected to freezing and thawing.'
2. Sulphate and alkali-aggregate concerns are addressed by other cement types in §1.8.
_Source: IGNOU ET-522 Block-1 Unit-1 Cement, §1.8.3, p. 12_
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