Relative compaction is a ration of the density of soil at site to the maximum dry density of soil.
like we have maximum dry density of soil have 1800 kg/m3 which determine in lab
now on site we can archive 1700 kg/m3 by compaction of dumped soil
so relative density of that soil on site is =1700/1800=0.9444 = 94.44%
it is use for
- to know how much density we archive compare to design in lab
- sometime in specification minimum criteria of relative density are given, ex- minimum relative density at whole site should be 90%.
- from relative density we can calculate actual movement of soil, which is very important in tall building and structural durability calculation