Field efflorescence test on bricks: after immersing a brick in water for 24 hours and drying, classify the extent of efflorescence based on surface coverage by grey/white deposits. Select the most complete and correct statement.
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AIf no grey or white deposits appear, the brick is free from soluble salts.
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BIf about 10% surface is covered, the brick has slight efflorescence.
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CIf about 50% surface is covered, the brick has serious efflorescence.
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DAll the above
Answer
Correct Answer: All the above
Explanation
Introduction / Context:Efflorescence indicates soluble salts migrating to the surface and crystallizing as the brick dries. This classification guides acceptance of brick lots for masonry.
Given Data / Assumptions:
- Test: soak brick 24 hours, dry, observe deposit coverage.
- Thresholds: none, slight (~10%), serious (~50%).
Concept / Approach:
Higher coverage means more soluble salts. No deposit implies acceptable salts level. Slight efflorescence may be tolerable for hidden work; serious efflorescence is typically unacceptable.
Step-by-Step Solution:
1) Apply the standard visual criteria to each observation.2) All three statements correctly map observations to standard classifications.3) Therefore the comprehensive correct choice is “All the above”.Verification / Alternative check:
Site QC manuals use deposit area coverage and presence of powdering/peeling to grade efflorescence severity.
Why Other Options Are Wrong:
Selecting any single condition ignores the full correct set of criteria.
Common Pitfalls:
Confusing slight with moderate; ignoring flaking/spalling that upgrades severity.
Final Answer:
All the above