Standard oven-drying for water content: Water content is determined as the mass loss after drying the sample for about 24 hours at which temperature range?

Introduction / Context:
Accurate determination of water content (w%) is fundamental in geotechnical testing. The drying temperature must be high enough to remove free/capillary/hygroscopic water but low enough to avoid altering clay minerals or driving off structural water. Standards specify a narrow oven temperature band for routine soils.

Given Data / Assumptions:

• Conventional oven method with 24-hour drying.
• Specimens not containing significant organic matter or gypsum (which may need lower temperature).
• Desire to preserve mineral structure.

Concept / Approach:

Most standards (e.g., common lab practice) recommend 105 ± 5°C; many texts cite 103–105°C to emphasize the lower bound that avoids damage to certain soils while ensuring consistent moisture removal. The listed choices include 103–105°C, which best reflects the standard range for general mineral soils.

Step-by-Step Solution:

Verification / Alternative check:

Lab QA/QC procedures commonly set ovens to 105°C with tolerance; 103–105°C falls within that envelope and is widely cited in question banks.

Why Other Options Are Wrong:

80–100°C may leave residual moisture; 105–110°C is used in some contexts but risks altering certain soils; the specified standard answer here is 103–105°C.

Common Pitfalls:

Using elevated temperatures for soils containing organic matter or gypsum; not allowing full 24-hour drying or not using airtight tins for cooling to prevent reabsorption.

Final Answer:

103° to 105°C