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Per the prevention measures in §2.2.12, the alkali content of cement to limit alkali-aggregate reaction is recommended to be:
A{'text': 'Less than 0.05 percent', 'label': 'A'}
B{'text': 'Less than 3.0 percent (or possibly 2.5 percent)', 'label': 'B'}
C{'text': 'Less than 0.6 percent (or possibly 0.4 percent)', 'label': 'C'}
D{'text': 'Less than 8.0 percent (or possibly 7.0 percent)', 'label': 'D'}
Answer & Solution
Correct answer: C. {'text': 'Less than 0.6 percent (or possibly 0.4 percent)', 'label': 'C'}
1. §2.2.12(ii) lists corrective measures and reads: 'Use low alkali cement; alkali content being less than 0.6 percent or possibly less than 0.4 percent.'
2. The high-alkali threshold that promotes AAR was earlier given as >0.6 percent.
_Source: IGNOU ET-522 Block-1 Unit-2 Aggregates, §2.2.12(ii), p. 25_
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