Investigations on the static behavior of self-compacting concrete under-reamed piles

Self-compacting concrete (SCC), a recent development, eliminates the need for internal or external vibration, as it freely flows in and around dense reinforcement and fills the mold completely without any blockages. SCC would be an ideal material for cast in situ piles, where compaction is infeasible. Six double under-reamed piles having a diameter of 250 mm and a length of 4 in, three made of SCC and three of conventionally vibrated cement concrete having similar strengths, were cast and tested to evaluate their static behavior in axial compression and tension (pullout). Later, all the piles were exhumed using suitable machinery to examine whether the pile shaft and bulbs had been well formed. Ultrasonic pulse velocity measurements were also taken on the exhumed piles along the length to evaluate the integrity of the concrete. Concrete cores of 75 mm diameter and 150 mm height taken from the pile shaft were tested for mechanical and durability related properties. The experimental study clearly demonstrated that the SCC in situ piles had better control on geometry when cast against soil form work.