Definition - What does Compaction mean?
Compaction is the process of increasing the density of soil by mechanical means resulting in the rearranging of soil particles and reduction of voids. Trenchless construction techniques, such as pipe ramming, work on the compaction principle by compacting and stabilizing the soil as the pipe is rammed in by mechanical force.
However; construction of all types require soil compaction to prevent settlement of soil over the course of time. Settlement can cause damage by inducing bending stresses and tilt of the structure where compaction is not adequate.
Trenchlesspedia explains Compaction
Compaction is carried out to ensure that the construction or installation is stable and does not settle over time. Compaction increases the bearing capacity of the soil and provides stability by increasing its shear strength, prevents damage by frost and reduces subsequent settlement under dead and live loads. It also reduces the permeability of soil thus preventing water from easily flowing through the soil and causing contraction and expansion.
Compacting can be carried out by vibration, impact, kneading or pressure depending on the soil type - cohesive or granular. Cohesive soils like clay are dense and closely bound, become plastic when wet and hard when dry. These soils require proper distribution of moisture to ensure proper compaction; impact and pressure methods work best.
Granular soils like sand and medium-sized gravel have water draining properties and are in the state of maximum density when fully dry or fully saturated; vibration works well for this soil type.