The GATE Grind

GATE 2025 CE (CE2) – Question 41

Geotechnical Engineering · Three-phase system, phase relationships, index properties and soil classification · 2 marks · Multiple choice

For a partially saturated soil deposit at a construction site, water content ($w$) is 15%, degree of saturation ($S$) is 67%, void ratio ($e$) is 0.6 and specific gravity of solids in the soil ($G_s$) is 2.67. Consider unit weight of water as 9.81 kN/m$^3$.
To fully saturate 5 m$^3$ of this soil, the required weight of water (in kN) will be ______ (round off to the nearest integer).

  1. 5
  2. 6
  3. 7
  4. 8

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (B) 6

Explanation

In 5 m³ of soil the volume of voids is $\frac{e}{1 + e} \times 5 = \frac{0.6}{1.6} \times 5 = 1.875$ m³. At present 67% of the voids hold water, so the water to be added fills the other 33%: $0.33 \times 1.875 = 0.619$ m³, whose weight is $0.619 \times 9.81 = 6.07$ kN, about 6 kN.