Effects of Salinity on the Consistency and Compressibility of Dredged Marine Clay

With the recent growth in coastal development, dredged clay has been increasingly used as a core reclamation material. However, marine clay may exhibit a consolidation behavior distinct from that of terrestrial clay owing to pore water salinity. In particular, salinity variations induced by environmental factors such as groundwater level fluctuations or seawater leaching can alter the compressibility and settlement behavior of clay deposits, thereby increasing uncertainty in settlement prediction. In this study, disturbed dredged clay was collected and remolded at different salinity levels (0%, 1%, 2%, and 3%) to investigate the effects of salinity variation on consistency and consolidation responses. The experimental results indicated that decreasing salinity increases the consistency indices (liquid limit and plastic limit) and clay compressibility. These trends are attributed to the expansion of the diffuse double layer and the consequent loosening of the clay microstructure under low-salinity conditions. These findings highlight the importance of considering pore water salinity for reliable settlement prediction and the rational design of dredged coastal reclamation grounds.