Section 4: Soil and Water Conservation Engineering
Soil Mechanics
Subtopic: Fundamental definitions and relationships
Question Statement:
A soil sample has a moisture content of $20\%$ (dry mass basis), void ratio $e = 0.65$, and specific gravity of soil solids $G_s = 2.60$. The degree of saturation of the soil expressed in percentage is ________ (answer in integer).
Answer Key:
80
Step-by-Step Solution & Explanation
Using the fundamental soil phase volumetric relationship:
$S \cdot e = w \cdot G_s$
Where:
• $w = 0.20$ (gravimetric moisture content)
• $G_s = 2.60$ (specific gravity)
• $e = 0.65$ (void ratio)
$S = \frac{w \cdot G_s}{e} = \frac{0.20 \times 2.60}{0.65} = \frac{0.52}{0.65} = 0.80 = 80\%$