How to Calculate Void Ratio

void ratio

The void ratio is the ratio of the volume of voids (open spaces, i.e. air and water) in a soil to volume of solids.

$$e = \frac{V_v}{V_s}\newline\newline

=\frac{V_g + V_w}{V_s}$$
Where:
e = Void Ratio
Vv = Volume of voids (m3 or ft3)
Vs = Volume of solids (m3 or ft3)
Vg = Volume of air (m3 or ft3)
Vw = Volume of water (m3 or ft3)

The void ratio is thus a ratio which can be greater than 1.  It can also be expressed as a fraction.

Void ratio and porosity differ only in the denominator.  Void ratio is the ratio of voids to solids, porosity is the ratio of voids to total volume.

About Bernie Roseke, P.Eng., PMP

Bernie Roseke, P.Eng., PMP, is the president of Roseke Engineering. As a bridge engineer and project manager, he manages projects ranging from small, local bridges to multi-million dollar projects. He is also the technical brains behind ProjectEngineer, the online project management system for engineers. He is a licensed professional engineer, certified project manager, and six sigma black belt. He lives in Lethbridge, Alberta, Canada, with his wife and two kids.

View all posts by Bernie Roseke, P.Eng., PMP

Leave a Reply

Your email address will not be published. Required fields are marked *

*