Continuous flight auger piles (CFA piles) are also commonly called augercast, augered cast in place piles (ACIP) or auger pressure grouted piles (APG). They are predominantly used in unstable soil conditions with a high ground water level when conventional drilling would require casing or drilling slurry to stabilize the bore hole.
CFA piles can be installed very efficiently with modern high-torque hydraulic drilling rigs up to a depth of 125 feet and 48 inches in diameter. Crane mounted lead systems extend the installation range beyond 170 feet, however, pile diameters are reduced with depth. Malcolm’s method for installing with the crane mounted lead system is called “CFA Mega Piles.” This method utilizes one continuous auger which is drilled into the ground. The soil on the auger prevents the surrounding ground from caving during the drilling and grouting process.
Close control of auger advancement and soil removal is essential to prevent loosening of the soil by excessive removal during the advancement of the CFA auger. After reaching pile tip, the auger is extracted while fluid concrete or grout is pumped through the hollow stem auger to fill the hole under positive pressure. Rebar is installed into the completed pile after the auger is removed.
CFA installations are highly productive and vibration free. Pile capacities of up to 1,500 tons can be achieved depending on the soil strata. The high productivity of this technology makes CFA piles most suitable for larger projects.