Void Ratio

e = \frac{V _{v}}{V _{s}}

Void ratio e is the volume of voids (air plus water) divided by the volume of solids. It is dimensionless; typical sands have e ≈ 0.3–0.9, and soft clays can exceed 1. Total volume V = Vs(1 + e). Dry unit weight falls as e rises: γ_d = Gs γ_w / (1 + e).

$e$: Void ratio
$V_{v}$ (m³): Volume of voids
$V_{s}$ (m³): Volume of solids
$V$ (m³): Total volume = Vs + Vv

Step-by-step solved example

A specimen has Vs = 0.62 m³ and Vv = 0.38 m³. Find e and total volume V.

e = Vv/Vs from the three-phase diagram.

1. Void ratio
e = Vv/Vs = 0.38/0.62 = 0.613.
$e = 0.613$
2. Total volume
V = Vs + Vv = 1.00 m³, or Vs(1+e) = 0.62×1.613 = 1.00 m³.
$V = 1.00 m^{3}$

Answer: e = 0.613, V = 1.00 m³

10 practice questions

0/10 correct

1.If Vv = 0.30 m³ and Vs = 0.70 m³, e is nearest

2.Void ratio e is the ratio of

3.For e = 0.80 and Vs = 1.0 m³, Vv equals

4.Soft normally consolidated clays often have e

5.Total volume in terms of Vs and e is

6.A sample with V = 1.20 m³ and e = 0.50 has Vs =

7.Compacting a soil at constant Gs mainly

8.e in terms of porosity n is

9.Vv includes the volumes of

10.γ_d = Gs γ_w / (1+e) implies that raising e