The use of glass waste in construction materials has gained increasing attention, particularly for window glass from insulating and simple glazing systems. This study investigates the feasibility of using such waste as aggregate in concrete, focusing on its effects on density, consistency, and mechanical properties. Waste glass was used as partial replacement of natural aggregates (up to 10 %), in both fine and coarse fractions. Results indicate a moderate decrease in compressive strength (from 29 - 30 MPa to 26 MPa), while maintaining values above 20 MPa, which are acceptable for structural applications. The particle size plays a key role, with the 0 - 2 mm fraction contributing to improved matrix densification and better performance. Overall, the findings demonstrate that insulating window glass waste can be successfully valorized as a sustainable alternative aggregate in concrete production, with limited impact on mechanical properties.