An experimental study on the mechanical and durability characteristics enhancements of sustainable concrete using waste glass

The proliferation of glass waste (GW) necessitates sustainable solutions, with its incorporation into concrete representing a promising approach. This study experimentally examines the dual application of GW-derived materials, glass powder (GP) as a partial cement replacement and glass sand (GS) as a substitute for natural sand, with varying water-to-cement ratios (w/c) of 0.35, 0.40, and 0.44. Glass concrete was prepared by replacing cement and sand with GW at varying levels (0%, 5%, 10%, 15%, 20%, 25%, and 30%). 30 concrete mixes were designed to evaluate the effects of incorporating GW on key performance parameters, including workability, density, compressive, splitting and flexural strengths, and water absorption. The test results demonstrate that slump flow increases with higher w/c ratios, reaching 250 mm in the mix with 30% GP, highlighting the combined effect of w/c ratio and GP in enhancing concrete flowability. Regarding compressive strength, an increase in both GP and w/c ratios led to continuous reduction in concrete strength, whereas the addition of GS resulted in a slight improvement. The most significant strength reduction, decrease to 35% of the original concrete's compressive strength, was observed in the mix containing 30% GP and a 0.44 w/c ratio. This decline is likely due to the smooth surface texture of the glass particles, which weakens the interfacial bond between the glass and the cementitious matrix. The optimal GS replacement and w/c ratios for improving splitting and flexural strengths are 20% and 0.35, respectively. Concrete density is influenced by the particle size of GW; 30% replacement of GP and GS with 0.44 w/c ratio reduced the density by 0.4% and 0.5%, respectively. Furthermore, GP and GS with 0.44 w/c ratio significantly reduce water absorption, by 24.5%, leading to a less permeable concrete. Overall, the combination of 5% GP and 20% GS at a 0.35 w/c ratio provides the best improvement in both internal microstructure and external durability of the concrete, compressive strength increased by 12%, and water absorption decreased by more than 20%. These findings highlight the potential of WG as a sustainable material for improving concrete performance, particularly when accounting for variations in the w/c ratio, offering significant environmental and engineering advantages.