Question

______ is an index of the fractional pore space in soil that relates space to the volume of solids rather than to the total volume of the soil.

• A. Void ratio
• B. Porosity
• C. Bulk density
• D. Pore size distribution

Hint:

The relationship between porosity (\( n \)) and void ratio (\( e \)) is given by:
\( e = \frac{n}{1-n} \) and \( n = \frac{e}{1+e} \).
Remember: Void ratio can be $> 1.0$, but porosity is always $< 1.0$ (or $< 100\%$).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Porosity and void ratio are both dimensional indices used to quantify the volume of pore spaces relative to other components of a soil sample.
Detailed Explanation:
Let us compare the mathematical definitions of porosity and void ratio:
- Porosity ($n$): It is defined as the ratio of the volume of voids ($V_v$) to the total volume of the soil ($V_t$).
\[ n = \frac{V_v}{V_t} \] This relates pore space to the *total volume*.
- Void ratio ($e$): It is defined as the ratio of the volume of voids ($V_v$) to the volume of solid particles ($V_s$).
\[ e = \frac{V_v}{V_s} \] This relates the pore space specifically to the *volume of solids* rather than the total volume.
- Bulk density is the mass of dry soil per unit bulk volume.
- Pore size distribution describes the relative abundance of pores of different sizes.
Therefore, the index that relates space to the volume of solids is the void ratio.

Step 2: Final Answer:
The blank is filled by "Void ratio", corresponding to option (A).