Augercast Piles (ACP), also known as Continuous Flight Auger (CFA) piles, are concrete bearing piles constructed by augering a hollow stemmed auger into the ground to a predetermined depth. Concrete is then forced down the hollow stem utilizing pump pressure. As the concrete is ejected from the tip of the auger, the auger is withdrawn such that spoil (augered dirt) is removed ahead of the concrete.

ACP’s are normally placed in groups under a unifying pile cap. This type of pile is usually 12 to 24 inches in diameter. Recent capacity increases in drilling equipment has resulted in it being possible to install auger cast piles at up to 48 inches in diameter. ACP piles act primarily in friction. They may be unreinforced, but are often lightly reinforced by placing a reinforcing rod or cage in the fluid concrete after withdrawal of the auger. Properly centering the reinforcing rod or cage, which is critical, is facilitated by the use of alignment aids during installation.*

* The above definition is based on information provided by Alan Macnab, P. ENG, D. GE. Macnab is the author of the “Earth Retention Handbook”, (McGraw-Hill), a leading text in the deep foundations and earth retention industries. He provides design and construction consulting services to the referenced industries. He can be reached at:

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