CFA & Rotary Bored Piles

Continuous Flight Auger Bored Piles

This method is constructed using a string of hollow stem augers which are drilled to a design depth depending on the pile load and ground conditions. Once this has been achieved concrete is then pumped through the auger as it is extracted maintaining a constant head pressure to avoid risk of any voids forming. A pile cage is then plunged into the concrete completing the pile.

Rotary Bored Piles

This method is constructed using a short lead section of auger which is attached to a telescopic Kelly bar. These piles are once again installed to a pre-determined design depth with spoil being removed gradually and ‘spun off’ to the side of the bore. This method may require either some temporary or permanent casing to ensure the stability of the bore is maintained. Due to the bores remaining open for the concreting process the level which the reinforcement and concrete is installed to can be controlled, allowing the top section of the pile to remain as open bore backfilled with sand rather than concrete. This is especially useful for scenarios where basement piles are being constructed from a high platform level reducing the amount of ‘waste’ concrete on site and aiding in the speed of dig.