Question

Why does only water is added for compaction of soil instead of adding oil or any other lubricating liquids?

Answer 1

Beyond a certain level of saturation, the bulk modulus of water starts playing an important role. Since water is nearly incompressible at moderate pressures, the pore pressure increases rapidly and equilibrates with the externally applied force when we try to compress the water. This makes it difficult to compact fully saturated soils and partially saturated soils with a large water content under confined conditions.

Answer 2

because With water plant can make food