The depletion of natural sand reserves and the accumulation of plastic and glass waste necessitate sustainable alternatives for concrete production, particularly for infrastructure in aggressive environments such as the Dead Sea region. This study evaluates the mechanical and durability performance of concrete incorporating waste glass powder and Low-Density Polyethylene (LDPE) granules as partial replacements for fine and Coarse aggregates. Experimental mixes included a control sample and variations with 10% glass powder combined with 5%, 10%, and 15% LDPE, subjected to standard curing and 3-month immersion in a 5% NaCl + 5% Na₂SO₄ saline solution. Mechanical properties were assessed through compressive and tensile strength tests, ultrasonic pulse velocity, and strain gauge measurements, complemented by microstructural analysis using SEM and XRF, and numerical validation via ABAQUS Concrete Damage Plasticity (CDP) simulations. Results indicated that the mix containing 10% GP and 5% LDPE showed optimal performance, reached a compressive strength of 46.63 MPa , compared to 42.47 MPa for the control. Notably, after saline exposure, this optimal mix showed a 47.49% strength increase, whereas the control suffered a 13.72% reduction, attributed to the pozzolanic reaction of GP and the hydrophobic barrier effect of LDPE. Microstructural analysis confirmed reduced efflorescence (salt crystallization) and ettringite formation in modified samples, while simulations (Abaqus) validated superior stress redistribution capabilities. These findings demonstrate that combining waste glass and LDPE enhances concrete ductility and resistance to chloride and sulfate attack, offering a viable sustainable solution for infrastructure in corrosive marine environments.