Void ratio

Void ratio, in materials science, is defined as the volume of voids in a mixture divided by the volume of solids. This figure is relevant in composites, in mining (particular with regard to the properties of tailings), and in soil science.

Engineering applications

• Volume change tendency control. If void ratio is high (loose soils) voids in a soil skeleton tend to minimize under loading - adjacent particles contract. The opposite situation, i.e. when void ratio is relatively small (dense soils), indicates that the volume of the soil is vulnerable to increase under loading - particles dilate.

• Hydraulic conductivity control (ability of water movement through the soil). Loose soils show high conductivity, while dense soils are not so permeable.

• Particles movement. In a loose soil particles can move quite easily, whereas in a dense one finer particles cannot pass through the voids, which leads to clogging.