Index Properties and Parameters of Soil
DEFINITIONS OF BASIC KEY TERMS OF SOIL
Water Content
Water content (w) is the ratio of the weight of water to the weight of solids.often expressed as a percentage
Index Properties of Soil
Void Ratio
Void ratio (e) is the ratio of the volume of void spaces to the volume of solids.The void ratio is usually expressed as a decimal quantity.
Index Properties of Soil
Porosity
Porosity (n) is the ratio of the volume of voids to the total volume of soil.
Index Properties of Soil
Degree of Saturation
Degree of saturation (S) is the ratio of the volume of water to the volume of voids.
Index Properties of Soil
Bulk Unit weight
Bulk unit weight (γ) is the weight density, that is, the weight of a soil per unit volume.
Index Properties of Soil
Saturated Unit Weight
Saturated unit weight (γsat) is the weight of a saturated soil per unit volume.
Index Properties of Soil
Dry Unit Weight
Dry unit weight (γd) is the weight of a dry soil per unit volume.
Index Properties of Soil
Effective Unit Weight
Effective unit weight (γ′) is the weight of a saturated soil submerged in water per unit volume.
Index Properties of Soil
Relative Density
Relative density (Dr) is an index that quantifes the degree of packing between the loosest
and densest state of coarse-grained soils.
Index Properties of Soil
Density Index
Density index (Id) is a similar measure (not identical) to relative density.
Index Properties of Soil
Unit Weight
Unit weight ratio or density ratio (Rd) is the ratio of the unit weight of the soil to that of
water.
Index Properties of Soil
Swell Factor
Swell factor (SF) is the ratio of the volume of excavated material to the volume of in situ
material (sometimes called borrow pit material or bank material).
Index Properties of Soil
Liquid Limit
Liquid limit (LL) is the water content at which a soil changes from a plastic state to a liquid
state.
Index Properties of Soil
Plastic Limit
Plastic limit (PL) is the water content at which a soil changes from a semisolid to a plastic
state.
Index Properties of Soil
Shrinkage Limit
Shrinkage limit (SL) is the water content at which a soil changes from a solid to a semisolid
state without further change in volume.
Index Properties of Soil
Plasticity Index
Plasticity index (PI) is the range of water content for which a soil will behave as a plastic
material (deformation without cracking).
Index Properties of Soil
Liquidity Index
Liquidity index (LI) is a measure of soil strength using the Atterberg limits (liquid and plastic
limits based on test data).
Index Properties of Soil
Shrinkage Index
Shrinkage index (SI) is the range of water content for which a soil will behave as a semisolid (deformation with cracking).
