C.F.A. Piles
C.F.A. piles, also known as Continuous Flight Auger piles, are a type of pile executed without the use of stabilizing fluids.
Construction of C.F.A. Piles
The execution involves rotating a helix (auger) into the ground to the desired depth (max 30m). During the advancement of the tool, the soil is extracted as it rises through the helix’s spirals, whose rotation directs the material towards the surface. The auger’s rotation also ensures that the borehole walls do not collapse.
Once the desired depth is reached, concrete is pumped through the hollow core of the auger. The controlled withdrawal of the auger, combined with continuous pumping, ensures that the borehole does not collapse, and it is completely filled.
After the total filling of the pile, the reinforcement cage is inserted.
The use of special SCC (self-compacting concrete) is essential, with aggregates having a maximum diameter of 1.5 cm and additives delaying the onset of the setting phase slightly and preventing disintegration. This allows the immersion insertion of the reinforcement cage due to its own weight.
Advantages / Disadvantages
- Higher execution speed
- No use of Bentonite mud
- Lower vibrations during construction
- Mandatory use of SCC (self-compacting concrete)
- Limit on maximum drilling length (approximately 30m)
- Limit on drilling diameter (1200mm)
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