For easy understanding, we write volume part on left and mass part on the right of the diagram.
When weight considers instant of mass, its written on the right side.
Vv =volume of voids
Va= volume of air
Vw= volume of water
Vs= volume of solid
V= total volume
Ma = 0 mass of air is very low so we neglect it.
Mw= mass of water, Ms = mass of solid, M= total mass
Three Phase Diagram of soil
Void ratio definition
Now because voids fill by air and water so we take
Va+Vw =Vv and
volume of solids = Vs
So e = Vv / Vs
Void ratio express in decimal ex- 0.3, 0.6 etc now
the void ratio greater than 1 mean soil contains voids more than the volume of solid. and less than mean reverse case.
the coarse grain soil is less void ratio than fine grain soil because fine grain soil is the mixture of small particles that particle contains chemical charge which not allows coming closer the particle. because particle does not come closer so its space fills with voids.
The generally void ratio is used in the calculation because we separate void volume and solid volume. if change happens its effect only one value as compare to porosity where both value change.
firstly say our soil mass consist of only Water and solid, that happens when the soil is fully saturated.
let’s say a soil mass consists of all three particles. Then we start adding water until its fully submerged,
now the air is gone and only two things remaining are Water and Solid
Its maybe only solid or air particle possibility in soil mass. that happens when you completely dry the soil mass,
so water evaporates and only solid and air remains. as shown in fig
That’s all about three phase system of soil, now we talk about volumetric relation ex – What is the void ratio, Porosity, Degree of saturation and air voids