Study Notes on Properties of Soils - Study Notes 1
Day 3 | Soil Properties | Study Notes
Properties of Soils
Soil mass is in general a three-phase system composed of solid, liquid and gaseous matter in a
blended form with each other.
But in phase diagram – for understanding, these three matters are shown separately.
In supersaturated, state with change in water content volume of voids changes hence volume of
The diagrammatic representation of the different phases in a soil mass is called the "phase diagram".
where, WW = Weight of power
WS = Weight of solids
There can be no upper limit to water content, i.e. w ≥ 0
where, Vv = Volume of voids
V = Total volume of soil
Porosity cannot exceed 100% i.e.,
0 < n < 100
Void ratio is more important engineering property.
Degree of Saturation
where, Vw = Volume of water
Vv = Volume of voids
0 ≤ S≤ 100
for perfectly dry soil : S = O
for Fully saturated soil : S = 100%
Va = Volume of air
Sr + ac = 1
% Air Void
na = n.ac
A. Bulk unit weight
Thus Bulk unit weight is total weight per unit volume.
B. Dry Unit Weight is the weight of soil solids per unit volume.
Dry unit weight is used as a measure of denseness of soil. More dry unit weight means more
C. Saturated unit weight: It is the ratio of total weight of fully saturated soil sample to its total volume.
Submerged unit weight or Buoyant unit weight (γ): It is the submerged weight of soil solids per unit
= unit wt. of saturated soil
γ = unit wt. of water
Unit wt. of solids:
γ is roughly 1/2 of saturated unit weight.
True/Absolute Special Gravity, G
Speciﬁc gravity of soil solids (G) is the ratio of the weight of a given volume of solids to the weight
of an equivalent volume of water at 4℃.
G = 2.6 to 2.75 for inorganic solids
= 1.2 to 1.4 for organic solids