Effect of recycled waste glass color on the properties of high-volume glass powder cement pastes

• Glass color has negligible effect on workability, setting time, and hydration • Glass color has few impacts on Portlandite content, density, porosity, and strength • Color sorting is unnecessary, reducing energy, labor, and environmental impact Recycled waste glass powder (RWGP) is a sustainable partial replacement for cement, reducing environmental impact and waste glass accumulation. This study examined whether glass color sorting is necessary to produce RWGP suitable for cementitious applications. Pastes were prepared with 50 wt% Portland cement replacement using RWGP fabricated from single glass colors (green, brown, and transparent) and mixed color glass, all with controlled RWGP particle size distribution. Their short- and medium-term characteristics were subsequently evaluated. Despite differences in appearance, all glass colors exhibited similar chemical compositions, containing about 69 wt% SiO 2 , 13 wt% Na 2 O, 9 wt% CaO, and 3 wt% Al 2 O 3 . Glass color had negligible effects on workability (slump ∼13.6 cm), initial and final setting times (∼216 and ∼313 min), maximum hydration temperature (∼60°C), and Portlandite content (∼5, ∼8, ∼10, ∼10, ∼7, and ∼5 wt% at 1, 3, 7, 14, 91, and 365 days, respectively). Dry density (∼1.9 g/cm 3 ) and total porosity (∼45, ∼35, ∼32, ∼30, and ∼22 % at 1, 7, 28, 91, and 365 days), as well as flexural (∼4, ∼6, ∼8, and ∼11 MPa) and compressive strengths (∼20, ∼28, ∼32, and ∼55 MPa at 7, 28, 91, and 365 days), were also unaffected. ANOVA and post-hoc comparisons confirmed that color sorting does not significantly influence Portlandite content, porosity, or mechanical properties. Therefore, color sorting, energy- and labor-intensive process, is unnecessary for producing RWGP. Using mixed-color waste glass simplifies recycling, reduces costs and environmental impact, and provides a practical/sustainable pathway for incorporating recycled glass into cementitious materials.