Oscillatory rheological properties and particle aggregation of marine clay with different pore-water salinities

Under complex oceanic dynamic loads, marine clay can undergo irreversible deformation. The mechanism of how salinity affects the mechanical behavior of marine clays remains an unresolved issue. In this study, artificial marine clays with varying pore-water salinities were tested through a series of oscillatory rheological tests, zeta potential and dynamic light scattering tests. The results demonstrated that within a salinity range of 0–10%, both storage modulus (G') and loss modulus (G'') at small strains initially decreased and then increased with salinity. A similar trend was observed for non-linear elastic parameters (GM and GL) and non-linear viscous parameters (ηM and ηL) at large strains. These parameters reached their minimum values at a 2.5% salinity. Particle aggregation size of marine clay first increased and then decreased with salinity. The zeta potential shifted from negative to positive beyond 5% salinity. This is attributed to the salinity-dependent interactions among clay particles. This study integrated oscillatory rheology with aggregation dynamics theory to elucidate the physical mechanisms governing marine clay behavior under varying pore-water salinities. These findings offer valuable insights for the safety assessment of marine engineering projects subjected to salinity fluctuations and dynamic loading.