Can you compact soil too much? Can soil be too compacted?

You may think that you can't over compact soil- the more compacted it is, the stronger it is, right? Wrong. Like anything, there is a breaking point. Over compaction will cause the soil to break down which reduces its support capability because of the separation that occurs within the soil mix itself.

Soil compaction occurs when soil particles are compressed together too tightly, reducing pore space between soil particles and preventing air and water from flowing at their optimum. Soil compaction impedes proper nutrient uptake and root growth, which can lead to the starvation of your crops.

The RIC is an innovative dynamic compaction device based on the piling hammer technology and is used to increase the load-bearing capacity of soils through controlled impacts. The general idea of this method is to drop a falling weight from a relatively low height onto a special foot assembly at a fast rate while the foot remains permanently in contact with the ground.

The compaction effect of the Rapid Impact Compactor is characterized by pulse-shaped loading of the ground and is achieved by a specific number of blows. The ground to be improved is both compacted and displaced depending on the soil type, thus, causing plastic deformations in the near-field while elastic waves are generated in the far-field. The nature of vibration excitation (transient or periodic) is one of the limiting factors for the allowable impact on buildings and human beings and has to be taken into account for the assessment of standardized limit values. 

The technique can usually be employed within 10-15m of sound structures with the vibrations significantly less than traditional dynamic compaction. RIC can also be used in shallow granular fills containing contaminants where penetrative ground improvement techniques such as Vibro Stone Columns would risk exposing contaminants to the atmosphere.  

One advantage of RIC is that the drop height and number of blows can be varied based on the soil conditions. Through a test program, we will work with the Geotechnical Engineer of Record (GER) to determine the appropriate improvement criteria and RIC set-up for various areas of the site. For a site with a mixed soil profile and varying thicknesses of sand and clay, the ability to accurately control the amount of energy delivered to the ground is critical as it allows one to improve the loose overlying loose soil without liquefying the fine grained soils below – providing more uniform compaction.