Utilizing Raw Desert Sand as a Sustainable Fine Aggregate: Impact on Concrete Performance and Environmental Benefits

The growing demand for sustainable construction materials has motivated the exploration of raw desert sand (RDS) as an alternative fine aggregate in concrete production. This study investigates the influence of RDS, combined with supplementary cementitious materials (fly ash and silica fume), on the long-term mechanical, durability, environmental, and economic performance of concrete at 270 days. Five concrete mixtures were designed with varying RDS replacement levels (0%, 25%, 50%, 75%, and 100%) for natural sand. Experimental results revealed that incorporating RDS significantly affected both strength development and water absorption. The highest compressive strength (68.13 MPa) was achieved with 75% RDS, while the maximum splitting tensile strength (4.18 MPa) and the lowest water absorption (2.51%) were recorded at 50% RDS. Although 100% RDS slightly reduced strength compared to the optimum mixes, it still outperformed the control mixture containing only natural sand. Beyond mechanical performance, RDS demonstrated tangible sustainability benefits. The embodied carbon footprint decreased by up to 2.48%, and cost savings reached 7.34% relative to conventional mixes. Furthermore, the eco-strength efficiency (strength-to-carbon ratio) improved substantially, confirming RDS as an eco-efficient aggregate. These findings highlight that RDS, an abundant and locally available resource in many regions, can serve as a cost-effective and environmentally responsible fine aggregate in concrete. The study concludes that optimal replacement levels of 50–75% offer the best balance between mechanical performance, durability, cost reduction, and carbon footprint mitigation, supporting the broader adoption of RDS in sustainable concrete applications.