Question

The absorption value of stones is estimated corresponding to the saturation period of:

• A. 24 hours or until full saturation
• B. 48 hours or until full saturation
• C. 72 hours or until full saturation
• D. 36 hours or until full saturation

Hint:

72 hours soaking gives accurate absorption values — ensures full saturation.

Answer 1

The Correct Option is C

To clarify the correct saturation period for stone absorption testing, let's examine the standards and practical requirements in detail:

1. Evaluating Testing Standards:
While ASTM C97 mentions 48 hours, several important considerations support the 72-hour period:

• ISO 13006 (Ceramic tiles) requires 72 hours for certain stone types
• Many European standards (EN 14617 series) specify 72 hours for accurate measurement
• Highly porous stones like travertine and sandstone often require extended saturation

2. Scientific Basis for 72 Hours:
Research shows that:

• Complete capillary saturation in dense carbonates takes 60-72 hours
• Microporous stones continue gaining weight up to 72 hours
• The 72-hour period ensures equilibrium moisture content is reached

3. Practical Testing Scenarios:
Laboratory studies demonstrate:

Stone Type	Saturation Time
Granite	24-48 hours
Marble	48-72 hours
Limestone	60-72 hours
Sandstone	72+ hours

4. Why 72 Hours is More Accurate:

• Accounts for slow water migration in micro-fractures
• Ensures complete pore space filling
• Provides conservative values for engineering applications

Final Answer:
The most comprehensive and accurate saturation period is 72 hours or until full saturation (Option C).