Rapid Impact Compaction – The Process

RIC is a technique allied to Dynamic Compacti?on that can be used to increase the bearing capacity of soils through controlled impact. The treatment is effecti?ve in the top layers typically up to 6m depth, though improvements up to 9m have been seen in some conditi?ons. A drop weight of 5 to 16 tonnes (depending on size) is dropped into a special foot assembly 40-60 ?times a minute. The foot remains in contact with the ground at all ?times.


  • Control: The machine is accurately controlled from excavator cab and the degree of compacti?on electronically monitored.
  • Safety: The impact foot is in contact with the ground at all ti?mes and eliminates the risk of flying debris. Unlike conventional DC; other activities can take place in close proximity
  • Quality Assurance: The impact energy and soil deflection are recorded by the on-board computer for presentation of compaction data to site managers. Results can verify work done to the client.The data can highlight weak zones where extra fill is required, or zones where underground obstructions were present (i.e. previously hidden old foundations)
  • Speed: The unit is mounted on standard excavators, typically in the 40-85 tonne class and can be mobilised in minutes from arrival on site.


  • Surface Consolidation: Final treatment of upper strata following traditional DC of the deepest layers
  • Foundations Support: Increase bearing capacity and reduce settlement
  • Floor Slab Support: Stiffen soils and create uniform bearing conditions
  • Liquefaction Mitigation: Increase shear wave modulus to help raise seismic site class
  • Waste Stabilisation: Reduce waste volume and improve properties of loose fills

RIC has been successfully used to consolidate gravel, sands, silts*, miscellaneous fills and industrial and mining waste fills. The ability to dump and compact sand or stone to depths up to 6m simplifies remediation practices. RIC is also less expensive than over-excavation and replacement techniques.


The method for efficiently covering the ground varies from country to country.

A common pattern used to cover uses a track in three passes (see diagram below). The outer (back) points being compacted first, followed by the intermediate (orange) lastly the infilling (blue) positions.

This has the effect achieving the best depth of influence. The first pass effecting the ground to a deeper level than the latter.


Most granular fills and some silts are compactable, the best results being achieve where the fill is a well-graded particle size. An area of 800m2 – 1600m2 can be covered in an average day (depending on the “blow-per-position” setting). This also allows time for routine maintenance and rotation of the special dolley pads located in the foot assembly which transfers the force of the blow through to the ground.

For detailed information about the RIC Process, click here.