Question

A borrow area soil material is sampled and weighs 1100 g. It is then over-dried in the lab till constant weight is achieved. This constant weight is 1000 g. If 1000000 MT of this soil is to be completed at 15% moisture content, then the quantity of water (in m³) required to be added to this soil will be
1. 15000
2. 100000
3. 50000
4. 1500
5. 5000

Answer 1

Correct Answer - Option 3 : 50000

Calculation:

Given,

Mass of soil, M = 1100 g

Mass of soil solids, M_d = 1000 g

Mass of water, M_w = 1100 - 1000 = 100 g

Mass of soil given = 10⁶ MT = 10⁹ kg

(1 MT = 1000 kg)

Water content, \(w = \frac{{{M_w}}}{{{M_s}}} \times 100 = \frac{{100}}{{1000}} \times \;100 = 10\% \)

Water added = 15% - 10% = 5 %

Water added, \({M_w} = \frac{5}{{100}} \times {10^6} \times {10^3} = 5 \times {10^7}kg\)

Volume of water added, \({V_w} = \frac{{{M_w}}}{{{\rho _w}}} = \frac{{5 \times {{10}^7}}}{{{{10}^3}}} = 5 \times {10^4}{m^3}\)

So, the quantity of water (m3) required to be added to this soil will be 50000 m³.