CFA piles or continuous flight auger piles are a special soil substituting pile type. The borehole wall is supported by the drill cuttings between the auger flights.
First a spiral threaded tube is inserted to the required depth. Thereafter the tube is rotated upwards and at the same time the tube lower end is filled with pumped concrete. The reinforced shell is vibrated into the concrete immediately after the spiral is entirely removed from the borehole. In comparison to conventional drill piles there are no problems with base cleaning. The stability of the drill hole walls is ensured. The surface water level does not sink with pile insertion so neighbouring structures are not damaged.
The piles replacing the soil can be used virtually in all soil types. The given method can be considered as vibration free making it suitable for piling in the immediate vicinity of existing buildings.