Analysis of Microscopic Characteristics of Marine Clay Under Salinity Influence: ESEM, Zeta Potential and DLS Tests

Marine clay serves as the natural foundation for various types of offshore and marine engineering structures and therefore plays a critical role in marine engineering practice. Consequently, a thorough understanding of the microstructural characteristics of marine clay is of great importance. In this study, two types of artificial marine clays with high and low clay contents were selected. Environmental scanning electron microscopy (ESEM), zeta potential measurements, and dynamic light scattering (DLS) tests were conducted to investigate the microstructure, surface electrical potential, and aggregation behavior of marine clay. The results revealed that the high-clay-content sample exhibited more compact particle connections, while the low-clay-content sample displayed a relatively loose structure. The addition of salt altered the particle distribution within the soil, increasing the aggregation of fine clay particles, which in turn compressed the diffuse double layer between particles. This caused changes in the surface electrokinetic potential of clay mineral particles and enhanced the stability of the soil samples. DLS tests on the high-clay-content sample showed that the aggregation state of clay particles was highly sensitive to salinity, with particle size initially increasing and then decreasing as salinity increased.