Multiobjective Optimization of Asphalt-Treated Base Courses Incorporating Recycled Concrete Aggregate and Powder: Balancing Performance and Sustainability

The global surge in construction and demolition waste (C&DW) has triggered severe environmental challenges, with infrastructure serving as the primary source, urgently requiring sustainable development through circular economy models. This study proposes a technical framework for asphalt pavement base-layer regeneration: synergistic utilization of 75% recycled concrete powder (RCP) as filler replacement and 0%–100% recycled concrete aggregate (RCA) as coarse aggregate replacement, with optimal performance achieved at 40%–60% RCA substitution rates to achieve high-value circulation of construction solid waste. Based on multiobjective optimization of technical–environmental–economic aspects, the study systematically evaluates performance, environmental, and economic benefits, and reveals RCP-RCA synergistic mechanisms and optimal trade-offs between performance and sustainability through multiscale analysis and life cycle assessment. Results show that when RCP is fixed, the RCA substitution rate correlates strongly linearly with asphalt-to-aggregate ratio; RCA incorporation significantly improves high-temperature and moisture sensitivity but reduces fatigue life, with performance degradation after exceeding the 60% critical substitution rate; compaction characteristics strongly positively correlate with high-temperature performance ( r = 0.928 ), and volumetric characteristics moderately correlate with low-temperature ductility ( r = 0.543 ); the coefficient of variation–technique for order preference by similarity to ideal solution (CVM-TOPSIS) model determines RCA40-60 as the optimal substitution scheme, significantly reducing net global warming potential (GWP) (16.82%–24.66%) and costs (6.84%–9.73%) while balancing performance; the constructed prediction model can evaluate service life under different traffic conditions, supporting sustainable pavement design decisions. This study provides a scientific basis for implementing a circular economy in road infrastructure, contributing to clean production in the construction industry and United Nations Sustainable Development Goals.