Specific Gravity of Soil

Specific gravity of soil, abbreviated as \(SG_s\), a dimensionless number, imeasures the density of soil particles compared to the density of water.  It is typically used in geotechnical engineering and soil science to classify and characterize soils.  The specific gravity of soil provides valuable information about the composition and porosity of a soil sample.

Specific gravity is used in various soil tests and calculations, such as determining the void ratio, porosity, and degree of saturation of a soil sample.  It is also essential in soil classification systems, such as the Unified Soil Classification System (USCS), which uses specific gravity as one of the criteria for classifying different types of soils.  Knowing the specific gravity of soil can help engineers and geologists understand its behavior, strength, and suitability for various construction and environmental applications.

Specific Gravity of Soil Formula
\( SG_s \;=\;  \dfrac{ \rho_s }{ \rho_w  }\)     (Specific Gravity of Soil) \( \rho_s \;=\;  SG_s  \cdot \rho_w   \) \( \rho_w \;=\; \dfrac{ \rho_s }{ SG_s   }\)
Symbol	English	Metric
\( SG_s \) = Specific Gravity of Soil	\(dimensionless\)	\( dimensionless \)
\( \rho_s \)  (Greek symbol rho) = Density of Soil	\( lbm \;/\; ft^3 \)	\(kg \;/\; m^3 \)
\( \rho_w \)  (Greek symbol rho) = Density of Water	\( lbm \;/\; ft^3 \)	\( kg \;/\; m^3 \)