From saturation to synergy: A dynamic impact assessment of decarbonization pathways for construction and demolition waste toward net-zero by 2050

Effective management of the environmental impacts of construction and demolition waste (CDW) is essential for rapidly urbanizing regions to achieve the 2050 net-zero target. However, existing building carbon emission forecasting studies are either based on single-method approaches that fail to capture long-term dynamics and evolving building stock characteristics or rely on hybrid models that remain limited in representing large-scale data heterogeneity and system feedback interactions. To address these limitations, in this paper a dynamic system-level framework is developed to examine the long-term evolution of CDW recycling systems under multiple interacting driving forces up to 2050. Seven scenarios are developed to assess both individual and combined effects of key intervention dimensions, including behavioral, policy, market, and technological factors. The results show that single-dimension interventions are characterized by saturation effects, where improvements diminish over time despite continued input intensification. Among isolated pathways, technological advancement performs the best, achieving a recycling rate of 40.0% and a 34.79% reduction in global warming potential (GWP) by 2050. Behavioral and policy-only pathways exhibit weaker impacts, with recycling rates limited to 18.8% and 20.5%, respectively. In contrast, the integrated pathway coordinating the evolution of technological, regulatory, market, and behavioral drivers enables a nonlinear transition toward high circularity. Under this scenario, the recycling rate increases by 94.30% and GWP is reduced by 93.75% compared with the baseline scenario, indicating that the integrated pathway effectively overcomes the saturation threshold observed in isolated intervention pathways.