Question

Statement (I): The zero-air void curve is non-linear.

Statement (II): The dry density at 100% saturation is a non-linear function of void ratio.
1. Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
2. Both Statement (I) and Statement (II) are individually true but Statement (II) is not the correct explanation of Statement (I)
3. Statement (I) is true but Statement (II) is false
4. Statement (I) is false but Statement (II) is true

Answer 1

Correct Answer - Option 1 : Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)

The dry unit weight of a soil can be related to its water content and degree of saturation as given below:

\({\gamma _d} = \frac{{G{\gamma _w}}}{{1\; + \;\frac{{wG}}{S}}}\)

Where, symbols have their usual meaning.

Now, for a given water content, the maximum theoretical dry unit weight can be obtained  from a soil by compacting that soil till no air voids are left i.e. soil becomes fully saturated or S = 1. This is called zero air void line or 100 % saturation line and it is given as:

\({\gamma _d} = \frac{{G{\gamma _w}}}{{1 + \;wG}}\)

We know that Se = wG

∴ \({\gamma _d} = \frac{{G{\gamma _w}}}{{1\; + \;e}}\)

From above formulas, it can be concluded that

1. The zero-air void curve is non-linear.

2. It is non –linear function of void ratio.

3. It non –linear function of water content.