How does RIC compact the road base?

Rapid Impact Compaction with the Rapid Impact Compactor (RIC) is an innovative method in the field of near surface and deep compaction techniques. The RIC is a dynamic compaction device based on piling hammer technology. Dynamic energy is imparted by a falling weight dropping from a controlled height onto a patented foot. The foot of the device remains in contact with the ground; thus, the energy is transferred to the ground safely and efficiently. 

The RIC, imparts energy by dropping a 5 to 9 tonne weight from a relatively small height of 1.2 m at a blow rate of 30 to 80 times a minute. Depending on the ram weight, the maximum energy delivered per blow is 59 to 106 kNm. Although the energy per blow is small compared to the conventional DC, the rapid blow frequency amply compensates, resulting in a greater power that varies between 2.4 to 6.4 MNm/min. Thus, a much greater total energy input per unit area of a site can be achieved with RIC. Moreover, the energy transfer of the RIC is far more effective due to its foot which stays in contact with the ground during the impact sequence. 

Typical areas of application could include projects such as low-rise structures like housing and schools, embankments, roads and pavement areas. Having the Rapid Impact Compactor mounted on a tracked machine gives it the versatility to move about in narrow and limited height spaces, such as within existing warehouses. With regard to its mobility, the RIC is able to be transported as a single unit, with the impact foot removed and the front end lowered horizontally on a flat-bed trailer. The machine can be ready to work just a few minutes after off-loading. If road restrictions apply, the unit can be easily split into two loads with the excavator travelling separately from the hammer. Re-assembly is achieved in less than two hours. 

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.

Typically, the RIC method is used for the treatment of essentially granular fills in order to improve their geotechnical properties (stiffness and bearing capacity) and to reduce settlement. RIC design firstly involves geotechnical characterisation of the soils to be treated, with emphasis placed on quantifying in-situ relative density and grading characteristics. Groundwater level is an important factor for consideration of suitability of the RIC method as shallow groundwater level can act as a hydraulic barrier reducing effective energy transfer to the fill materials. However, it is the “compaction trial” (discussed under testing and quality control), which provides the designer with the necessary information to permit refinement of the design. With ground improvement techniques involving surface impact such as RIC there cannot be direct control of treatment depth, as would be the case with vibro stone columns. A critical element of RIC design therefore is the depth to which a particular treatment is effective.