<![CDATA[Coastal embankment structures require mortar with adequate early-age strength and high resistance to degradation in aggressive marine environments. Utilizing sea sand and seawater as mortar constituents offers the potential to reduce the exploitation of freshwater and river sand resources; however, it raises concerns regarding the impact of chloride and sulfate ions on mechanical properties and durability. This study aims to investigate the early-age strength development of marine-based mortar, assess changes in water absorption and compressive strength resulting from wet-dry cycles, and evaluate microstructural degradation resistance against durability standards for tidal zone protective layers. Experimental methods included aggregate characterization, compressive strength and water absorption testing, and microstructural analysis using SEM and EDS. Results indicate that sea-sand/seawater mortar specimens immersed in seawater exhibited compressive strength increases from 9.33 MPa (3 days) to 10.67 MPa (7 days) and 10.00 MPa (28 days), whereas river-sand/seawater mortar reached 12.67 MPa at 28 days. Water absorption decreased with age, reaching 3.20% at 28 days. SEM-EDS analysis revealed a dense matrix containing hydration products and detected Cl, Na, Mg, and S elements resulting from exposure to the marine environment. Overall, the findings confirm the potential of sea-sand and seawater-based mortar as a protective barrier material for coastal structures and tidal zones.]]>
