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Per §10.8 (Step 8), the correction applied to mix proportions when site aggregates are found to be ABSORBING (drier than SSD) is:
A{'text': 'Add extra water and adjust aggregate weights downward by the same mass', 'label': 'A'}
B{'text': 'Reduce all aggregate weights by 50 percent for absorption', 'label': 'B'}
C{'text': 'No correction is ever needed for moisture state of aggregates', 'label': 'C'}
D{'text': 'Increase the cement content by 10 percent', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': 'Add extra water and adjust aggregate weights downward by the same mass', 'label': 'A'}
1. §10.8 Step 8: 'If… aggregates are absorbing type then it will absorb moisture from mixing water to attain SSD condition. Hence in such condition extra water is to be added with mixing water to maintain the water cement ratio constant…' The aggregate weights from Step 7 are simultaneously reduced by the same mass of absorbed water.
2. If aggregates are moist (wetter than SSD), the corrections are reversed: subtract free water from mixing water, add equivalent moisture-free weight to aggregates.
_Source: IGNOU ET-522 Block-3 Unit-10 Concrete Mix Design, §10.8 Step 8, p. 19_
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