Degree of Saturation
It is defined as the ratio of the volume of water (Vw) to the volume of voids (Vv) present in a given soil mass. It is represented as ‘s’.
s = (Vw / Vv)*100.
Degree of Saturation is the Unit less.
0% ≤ s ≤ 100%.
Type of Soil According to Degree of Saturation
Depending upon the degree of saturation in a given soil mass it can be classified as:
| Type of soil | Degree of Saturation |
| dry soil | ( s≤0) |
| humid soil | (0<s<.25) |
| damp soil | (.25<s<.5) |
| moist soil | (.5<s<.75) |
| wet soil | (.75<s<1) |
| saturated soil | (s≥1) |
Air Content (ac)
It is defined as the ratio of the volume of air (Va) to the volume of voids (Vv) present in a given soil mass. It is represented as ‘ac’.
ac = (Va / Vv)*100.
Air Content (ac) is the Unit less.
0% ≤ ac ≤ 100%.
⇒Vv = Va + Vw. (Divide by Vv on both side).
⇒Vv/Vv = Va/Vv +Vw/Vv.
⇒ac+ s =1.
Percentage Air Voids (ηa)
It is defined as the ratio of the volume of air (Va) to the volume of soil mass (V) present in a given soil mass. It is represented as ‘ηa’.
ηa= (Va / V)*100
Percentage Air Voids is the Unit less.
0% ≤ ηa < 100%.
ηa= Va/V.
ηa= (Va*Vv) / (V*Vv). ( Multiply Numerator & Denominator by Vv.)
ηa= (Va/Vv) * (Vv/V).
ηa= ac×η.
| Subject | Soil Mechanics |
| Unit | Soil Formation & Properties of Soil |
| Topic | Degree of Saturation, Air Content, Percentage Air Voids |
| Next Topic | Unit Weight and Density |
| Previous Topic | Void Ratio and Porosity of Soil |