CFA Piling

The Continuous Flight Auger / CFA pile is a non-displacement pile used where fast, vibration free installation is required in difficult ground conditions. The drilling process is suitable for penetrating dense layers and is unaffected by ground water or collapsing soil conditions.

The pile is formed by first drilling into the ground with a hollow-stemmed continuous flight auger. Cement-sand grout or concrete is then injected under pressure through the auger’s hollow stem as it is being withdrawn with no casing required. The grout or concrete pressure is maintained during the auger withdrawal so that it assists the extraction as well as exerting a lateral pressure on the surrounding soils. On completion of this operation, a reinforcing cage is placed into the fluid column of grout or concrete.

CFA piles cause minimal disturbance and are often used for noise and environmentally sensitive sites, although they are not generally suited for use in contaminated soils due to expensive waste disposal costs. In cases such as these however a displacement pile may provide the cost efficiency of an augercast pile and minimal environmental impact.