CFA piles are a form of rotary bored piles but without the use of temporary casing and/or a drilling fluid.
A hollow-stem auger is rotated inside the top soil using the rotary drilling rig till the auger reaches the design depth or until resistance is encountered in consolidated soils or soft rocks. Upon reaching the desired depth, the auger is rotated in the reverse direction and slowly lifted while at the same time lean concrete is pumped through the auger, thus replacing the soft soils with fresh concrete. The process of drilling, lifting of auger and concreting is controlled through onboard computer controlled instrumentation.
