The subsurface which includes soils and rocks is the ultimate load bearing stratum. Geotechnical engineering is the branch of civil engineering that deals with the engineering behavior of subsurface or earth materials. It includes (a) soil mechanics, which is essential to identify, characterize and study the mechanics of soil/ rock and (b) applied soil mechanics, which transfers the behavioral knowledge to practice. This includes investigating existing subsurface conditions and materials; determining their engineering behavior that are relevant to the project considered, assessing risks posed by site conditions; designing earthworks and foundations. 

A typical geotechnical engineering laboratory helps in identifying the engineering behavior of geomaterials (soils and rocks) and byproducts such as fly ash etc. There are different physical, chemical and geotechnical properties determined in the laboratory that is required for identifying the geomaterials. This information is used by geotechnical engineer for designing the type of foundations, earthworks such as dams, embankments, tunnels, reservoirs, pavement sub grades, and specialized applications like waste containment systems. The preciseness of such design is entirely based on the experimental information obtained from a geotechnical laboratory. Therefore, geotechnical engineering laboratory has a great role to play in rendering the subsurface a safe and stable load bearing medium.