EcoMarble: macro-performance and carbon footprint optimization of concrete using cement-substituted Al-Kharj marble dust

Abstract This study investigates the sustainable utilization of Al-Kharj marble dust (MD) as a cement substitute in concrete, evaluating its effects on mechanical properties and environmental impact. Cement was partially replaced with 5–30 % marble dust by weight, and the resulting mixtures were assessed through comprehensive experimental methods including compressive strength (ASTM C39), flexural strength (ASTM C78), tensile strength tests, porosity measurement, and life cycle assessment (LCA) using SimaPro software. The results demonstrate that 15 % marble dust replacement provides the optimal performance, achieving 26.41 MPa compressive strength (+5.4 % vs. control), 14.55 MPa flexural strength (+2.1 %), and 9.44 MPa tensile strength, while reducing porosity by 68 %. Environmental analysis revealed a 34 % reduction in carbon emissions (285 vs. 430 kg CO 2 -eq/m 3 ) and a 30 % decrease in cement cost. The findings establish marble dust as a viable sustainable material that enhances concrete performance while reducing environmental impact, offering a practical solution for waste valorization in construction applications.