Characteristics of composite ground improved by recycled-aggregate porous concrete pile

In this study, a series of laboratory chamber tests was carried out to evaluate the applicability of a porous concrete pile fabricated with recycled aggregates for soft ground improvement. The recycled-aggregate porous concrete pile (RAPP) has been developed to replace for natural aggregates and to overcome technical problems associated with the conventional compaction piling systems. The laboratory chamber tests for evaluating the performance of RAPP were carried out with a cylindrical mold of 280mm in internal diameter and 580mm in height. A replacement area ratio of 5% and three different loading steps were applied in the chamber tests. The experimental results of the surface settlement, excess pore pressure and vertical stress distribution versus time were compared with those of the sand compaction pile (SCP) reinforced composite ground under the same experimental condition. The current study shows that the settlement reduction in the RAPP-reinforced system is significantly enhanced due to load transfer from the soil formation to the RAPP. Furthermore, the comparison of consolidation rate shows that the RAPP can also accelerate the consolidation of soft clay formation because the RAPP behaves as a vertical drain.