Question

In a compaction test, G, w, S and e represent the specific gravity, water content, degree of saturation and void ratio of the soil sample, respectively. If ${\gamma }_w$ represents the unit weight of water and ${\gamma }_d$ represents the dry unit weight of the soil, the equation for zero air voids line is

• A. ${\gamma }_d=\frac{G_{{\gamma }_w}}{1+Se}$
• B. ${\gamma }_d=\frac{G_{{\gamma }_w}}{1+Gw}$
• C. ${\gamma }_d=\frac{Gw}{1+{\gamma }_{w}S}$
• D. ${\gamma }_d=\frac{Gw}{1+Se}$

Answer 1

The correct option is B ${\gamma }_d=\frac{G_{{\gamma }_w}}{1+Gw}$

Dry unit weight,

${\gamma }_d=\frac{G_s{\gamma }_w}{1+e}=\frac{G_s{\gamma }_w}{1+\frac{wG}{S}}$

For zero air void line, degree of saturation

= 100%

i.e., S = 1

${\gamma }_d=\frac{G_{{\gamma }_w}}{1+Gw}$