Cased Continuous Flight Auger (CCFA) piles

what are ccfa piles?

Cased Continuous Flight Auger (CCFA) piles are a type of cast-in-place deep foundation that combines the efficiency of continuous flight auger drilling with the added stability of temporary casing.

CCFA piles are installed utilizing dual rotary drilling techniques where the outer temporary casing rotates in an opposite direction from the inner continuous flight auger. It is generally used where borehole stability is required such as drilling a secant wall or piles immediately adjacent to a building. The auger and casing are advanced to the specified design depth where concrete is then pumped through the hollow stem of the auger. The temporary casing and auger are then withdrawn in a controlled manner, leaving a continuous concrete shaft in the ground. Once the auger is removed from the ground and the borehole is filled with concrete, steel reinforcing is placed.  The steel reinforcing can consist of a circular cage,  one center bar, or both, depending on project requirements. 

what are the advantages of ccfa?

The temporary casing supports the surrounding soil during installation, helping maintain the integrity of the excavation in loose or unstable ground. Because CCFA piles are installed through a drilling process rather than pile driving, they generate significantly less vibration than driven pile systems. The continuous drilling and concrete placement process allows piles to be installed in an efficient and controlled manner. The combination of low vibration, controlled installation, and adaptability to difficult ground conditions makes CCFA piles a valuable solution for urban foundation projects.