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.

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:

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