Why proctor is performed and where value is used?

The standard Proctor is a laboratory test performed in order to determine the maximum dry density and optimum moisture content of a given soil. This test usually conforms to ASTM D698. Results from the Proctor test are mostly used to determine the relative compaction of fill soils by dividing the dry density of the fill soil by the maximum dry density from the Proctor. Themodified Proctor (ASTM D1557) is a different, but similar, laboratory test used for the same thing. The modified Proctor usually yields a higher maximum dry density of about 5% with relation to the standard effort (Proctor)

The proctor compaction test is a laboratory geotechnicial  testing method used to determine the siol compaction properties, specifically,to determine optimum moisture content at which soil can reach its maximum dry density.