Soil Index Quantities – Determining the Void Ratio of a Soil Sample The void ratio e of a soil is defined as the ratio of the volume of voids to the volume of solids. Based on standard geotechnical definitions (independent of any external reference like Q. No. 216), which value below best represents a typical medium-dense soil's void ratio?

Introduction / Context:
The void ratio e is a core soil index property defined as V_v / V_s, where V_v is the volume of voids and V_s is the volume of solids. It is widely used in compaction control, compressibility, and permeability correlations. This question checks conceptual awareness of realistic magnitudes for e in typical field soils when no special conditions are imposed.

Given Data / Assumptions:

• No prior problem context is required; we use standard ranges.
• Granular soils (sands) often have e roughly 0.4 to 0.8 depending on density.
• Fine-grained soils can show larger e, but common design values still lie near unity or below.

Concept / Approach:

Void ratio e connects directly to porosity n via n = e/(1 + e). For a medium-dense sand, n may be about 0.375–0.45. Back-computing gives e around 0.6–0.82. In many textbooks and laboratory experiences, e ≈ 0.60 is frequently encountered for medium-dense granular soils and compacted fills. The answer reflects a realistic, representative magnitude rather than an extreme loose or very dense case.

Step-by-Step Solution:

Verification / Alternative check:

Compaction specifications and index property tables often present e values in the 0.4–0.8 band for sands; e = 0.60 lies at a realistic midpoint, aligning with many field compaction outcomes.

Why Other Options Are Wrong:

0.40 typically indicates very dense packing for many sands; 0.75 suggests looser states; 0.50 is possible but less representative of a midpoint than 0.60 in generic discussions; 'None of these' is unnecessary because one plausible central value is provided.

Common Pitfalls:

Confusing porosity n with void ratio e; assuming a single 'correct' e for all soils without acknowledging density state variations.

Final Answer:

0.60