Résumé
The increasing demand for natural sand in construction and tightening environmental regulations have prompted interest in alternative materials for concrete production. This study explores the use of untreated dredged marine sediments as a 30 % partial sand replacement in marine concrete. Two mixtures, a reference concrete (RC) and a marine sediment concrete (MSC), were evaluated before and after 70 days of seawater immersion. The experimental program evaluated compressive strength, durability (porosity, permeability, and chloride ingress), biocolonization potential, and environmental and economic viability through Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA). The results indicate that MSC achieves compressive strength comparable to RC (58.6 MPa vs. 59.7 MPa at 28 days) with lower gas permeability (64.3 × 10⁻¹⁸ m² for MSC vs. 88.9 × 10⁻¹⁸ m² for RC), suggesting a denser microstructure. Although MSC showed a higher initial chloride content (0.11 % vs. 0.05 %), this is attributed to the chloride-bearing sediment. Notably, MSC demonstrated faster biocolonization, indicating stronger ecological integration in marine environments. From a sustainability perspective, MSC reduces environmental impacts associated with sand extraction, promotes the reuse of dredged sediment, and lowers production costs. These findings suggest that MSC could be a promising material for eco-designed coastal infrastructure such as reefs, breakwaters, and offshore foundations. However, further research is needed to evaluate long-term performance, optimize mix design, and validate large-scale applications for sustainable marine construction