Effects of Lime-Clay Modification on the Consolidation Behavior of the Dredged Mud

A series of laboratory tests was performed to evaluate the effect of clay fabric, altered due to the addition of hydrated lime into slurry, on the primary and secondary consolidation behavior of dredged mud samples. In this research, the seepage-induced consolidation test is proposed as a technique to determine the threshold value of lime, below which maximum flocculation of the clay particles takes place. A series of oedometer tests was conducted on lime treated samples in both normally consolidated (NC) and artificially over-consolidated (OC) states. The results obtained in NC range showed that both the coefficient of consolidation and compression index increased as the lime content increased. Under the same value of effective stress, with varying the amount of lime, the compression index increased and secondary compression index reduced, resulting in a gradual reduction of C-alpha/C-c value. The laboratory results show that in the OC state and with surcharging, both the secondary compression index and recompression index reduced when the percentage of lime increased. However, it was observed that the surcharging effort has less impact on secondary compression as the percentage of lime increased. This study may encourage an innovative ground improvement technique, in which dredged mud slurry can be mixed with lime prior to discharging into a containment pond in order to optimize the effectiveness of preloading on the dredged mud layer.