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Void ratio and porosity

The spaces between the grains are called pores. The void ratio is the pore volume divided by the grain volume, while the porosity is the pore volume divided by the total volume. The void ratio can exceed 1 in soft clay, the porosity never can.

e=VpVse = \frac{V_p}{V_s}void ratio
n=VpV=e1+en = \frac{V_p}{V} = \frac{e}{1 + e}porosity

Symbols

eevoid ratio
nnporosity
VpV_ppore volumem³
VsV_sgrain volumem³

Example

e=0.6e = 0.6:

n=0.6/1.6=0.375n = 0.6/1.6 = 0.375.

A high void ratio means loose soil that can be compressed a lot.
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Part of Geotechnical Engineering: Soil and classification.