Recycled Concrete in Foundations: Mechanical and Environmental Insights

Recycled aggregate concrete (RAC) has significant potential for sustainable construction; however, concerns regarding its mechanical performance and environmental impact persist. This study evaluates 26 RAC mixtures with varying cement content, water–cement ratios, and recycled aggregate replacement levels (30%, 50%, and 100%) using two distinct recycling processes. The results confirm that while RAC exhibits a decline in mechanical properties compared to natural aggregate concrete (NAC), lower-strength concrete classes maintain acceptable performance. The Life Cycle Assessment (LCA) indicates that fully replacing the natural aggregate with a high-quality recycled aggregate reduces environmental impact by nearly 50%, primarily due to lower resource depletion and transportation emissions. The study demonstrates that RAC can be optimized for structural applications, particularly in foundation structures, without compromising functional integrity. Unlike previous studies, this research provides a systematic evaluation of how a two-stage recycling process enhances aggregate quality, leading to improved RAC performance, and introduces practical strategies for optimizing RAC durability and mix design for real-world foundation applications. Future research should explore alternative mix designs and durability improvements to enhance RAC’s viability for broader construction applications.