Bachy Soletanche developed a threaded continuous flight auger (CFA) piling technique, which offers a similar level of productivity, load bearing capacity, and settlement performance to the traditional CFA method but with a lower cost and less impact on the environment.
Threaded CFA piles use approximately 30% less concrete compared to traditional 750mm diameter CFA piles, thus they significantly reduce spoil disposal volumes, further adding to the technique’s environmental credentials.
To develop this solution, Bachy Soletanche designed a special cutting head with a retractable threading tooth to replace the normal cutting head located at the bottom of the continuous flight auger. Once the auger is screwed to the required depth, the threading tooth is extended to 750mm. The concrete is then pumped through the stem whilst the auger is being rotated and withdrawn from the ground, thus forming the threaded pile.
The minimal size of the mechanism, coupled with its powerful tool ejection system, ensures that the threaded CFA technique can be used in a wide range of ground conditions.