CFA piles are generally referred to as Auger Pressure Grouted Piles (APG), Augercast, or Augered Cast In Place Piles (ACIP). They are largely used in unstable soil settings with an elevated ground water level when standard drilling would call for casing or drilling slurry to steady the bore hole.
CFA piles can be installed very efficiently with current high-torque hydraulic drilling rigs up to an extent of 115 feet and 48 inches in diameter. Crane mounted lead systems lengthen the fitting range further than 150 feet, however, pile diameters are reduced with depth.
The technique utilizes one constant auger which is drilled into the ground. The soil on the auger stops the immediate ground from caving during the course of drilling and grouting. Close management of auger progression and soil extraction is essential to avoid loosening of the soil by excessive removal throughout the progression of the CFA auger. Once reaching pile tip, the auger is removed while fluid concrete or grout is pumped through the hollow stem auger to fill the hole under positive force. Rebar is installed into the finished pile after the auger is extracted. CFA installations are vastly productive and vibration free.