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Per §4.7.4, the dosage of air entrainment for ordinary concrete should generally be kept within the range:
A{'text': '0.1 to 0.5 percent of the mix', 'label': 'A'}
B{'text': '10 to 12 percent of the mix', 'label': 'B'}
C{'text': '2 to 6 percent of the mix', 'label': 'C'}
D{'text': '15 to 20 percent of the mix', 'label': 'D'}
Answer & Solution
Correct answer: C. {'text': '2 to 6 percent of the mix', 'label': 'C'}
1. §4.7.4 closes: 'In any case air entrainment should not be less than 2 percent and more than 6 percent.'
2. For mass concreting 2-3 percent is recommended; thin sections take 5-6 percent; reinforced concrete typically 3-4 percent.
_Source: IGNOU ET-522 Block-1 Unit-4 Admixtures, §4.7.4, p. 51_
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