The moisture content in a soil sample is 18.2% and specific gravity of the soil particles is given by 2.65. What is the void ratio for sample, if the soil is fully saturated?

📝 Detailed Explanation

Given: moisture content w = 18.2% = 0.182, G = 2.65, soil fully saturated (S = 1).

From the fundamental relation eS = wG, with S = 1: e = wG = 0.182 × 2.65 = 0.4823, matching option (c) 0.482.

💡 Key Concepts for Students

• For fully saturated soil (S = 1), the general relation eS = wG simplifies neatly to e = wG.
• This is the reverse operation of Q20 — there, e and G were given to find w for saturation; here, w and G are given to find e directly.
• Recognizing when S = 1 (fully saturated) is what allows this simplification — always check the problem statement for saturation before choosing which form of eS = wG to use.
• This relationship (e = wG for saturated soil) is frequently used to back-calculate void ratio from a simple water content and specific gravity test when the soil is known to be saturated (e.g., soil below a water table).