Combined Effect of Glass Powder and Recycled Sand on Fresh and Hardened Properties of Steel Fiber-Reinforced Self-Compacting Concrete

This study investigates the synergistic effects of waste glass powder and recycled sand on steel fiber-reinforced self-compacting concrete through systematic mixture optimization. Waste glass powder (WGP) and recycled sand (RS) from construction demolition waste were evaluated as sustainable replacements for cement and natural aggregates. The experimental program examined WGP replacement levels of 5-20%, RS substitution of 15-60%, and hooked-end steel fiber incorporation at 0.3-1.2% by volume, maintaining water-to-binder ratio of 0.42 with optimized superplasticizer dosage. Fresh properties were assessed through standardized workability tests including slump flow, V-funnel, and L-box evaluations, while hardened performance encompassed compressive and flexural strength development alongside durability parameters. Design-Expert 13 software facilitated response surface methodology optimization, revealing complex material interactions that challenge conventional additive assumptions. The optimal sustainable formulation comprising 15% waste glass powder, 15% recycled sand, and 0.9% steel fibers achieved balanced performance characteristics. This mixture demonstrated compressive strengths of 53.4 MPa at 28 days, progressing to 64.8 MPa at 90 days, enhanced flexural capacity of 8.2 MPa, and reduced water absorption from 4.2% to 3.8%. Fresh properties remained within acceptable self-compacting concrete criteria despite substantial waste material incorporation. The research demonstrates that waste-derived materials enhance concrete performance when integrated through systematic design approaches, advancing sustainable construction technologies.