Effect of Slime on Engineering Characteristics of Large-Diameter Cast-in-Place Pile

Slime forms at the bottom of boreholes under the effect of groundwater. The larger the borehole, the more the slime. The demand for large-diameter cast-in-place (CIP) piles has increased as the number of large structures has increased. Excessive slime management can delay construction. However, the effect of slime on the engineering characteristics of large-diameter CIP piles is not understood. In this study, the strength of slime-concrete mixtures was investigated by varying the volume ratio of slime. Field-scale testing was performed to evaluate the behavior of the large-diameter CIP pile using bidirectional load testing. A numerical analysis was performed to assess the compressibility of the slime under the self-weight of the pile. The results revealed that the general levels of slime at the bottom of the borehole had an insignificant influence on the engineering characteristics of the large-diameter CIP pile because the slime is susceptible to being mixed with poured concrete and compressed by the self-weight of the pile.