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Per §8.5.5 (ASTM frost-damage durability factor), the test is run for 300 cycles or until the dynamic modulus of elasticity drops to what percent of its original value, whichever occurs first?
A{'text': 'About 25 percent of the original modulus', 'label': 'A'}
B{'text': 'About 99 percent of the original modulus', 'label': 'B'}
C{'text': 'About 90 percent of the original modulus', 'label': 'C'}
D{'text': 'About 60 percent of the original modulus', 'label': 'D'}
Answer & Solution
Correct answer: D. {'text': 'About 60 percent of the original modulus', 'label': 'D'}
1. §8.5.5: 'A.S.T.M. calculates durability factor by continuing freezing and thawing for 300 cycles or until the dynamic modulus of elasticity is reduced to 60% of its original value, whichever occurs first.'
2. Durability factor = (cycles at end × % original modulus) / 300.
_Source: IGNOU ET-522 Block-2 Unit-8 Durability of Concrete, §8.5.5, p. 75_
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