Question

Which relationship is correct between dry unit weight, specific gravity, percentage air void and water content?
1. γ_d = (1 – n_a) G γ_w / (1 + wG)
2. γ_d = (1 + n_a) G γ_w / (1 - wG)
3. γ_d = (1 + wG) /(1 – n_a) G γ_w
4. γ_d = (1 - wG) /(1 + n_a) G γ_w

Answer 1

Correct Answer - Option 1 : γ_d = (1 – n_a) G γ_w / (1 + wG)

Concept

Dry unit weight is given by

\({γ _d} = \frac{{\left( {1 - {\eta _a}} \right)\times G \times {γ _w }}}{{1 + w G}}\)

where,

 η_a is percentage air voids, G is Specific gravity

 w is water content, γ_w is unit weight of water

 γ_d is dry unit weight