Modeling the environmental benefits of recycling infrastructure demolition waste into recycled aggregate concrete bricks

The continued growth of infrastructure demolition waste (IDW) in China highlights a persistent mismatch between waste generation and resource recovery capacity. Recycling IDW into recycled aggregate concrete bricks (RACB) offers a scalable pathway to alleviate environmental pressures while promoting circular construction practices. However, existing studies are constrained by fragmented life-cycle inventories, static project-level system boundaries, and the lack of dynamic representations of infrastructure-derived waste streams. Consequently, they fail to comprehensively track material flows or elucidate the broader environmental consequences associated with large-scale RACB deployment. In response, we develop an IDW-to-RACB environmental benefit assessment (IREBA) model to quantify the environmental benefits of recycling IDW into RACB across various policy scenarios. Our results show that from 2020 to 2060, IDW recycling could cumulatively generate 1583.85 Mt of recycled aggregate, which is adequate for 1836.63 Mt of RACB fabrication. Regarding source composition, RACB derived from ordinary highway demolition accounts for majority share (81.54%), followed by contributions from railways (8.70%), urban roads (6.42%), and expressways (3.33%). Recycling IDW could avoid 84.30 Mt CO₂-eq, 10.98 t CFC-11-eq, 0.032 Mt PM_2.5-eq, 0.016 Mt 1,4-DB-eq, 95.68 t P-eq, and 0.094 Mt SO₂-eq. It could also conserve 11.57 Mt oil-eq in energy consumption and reduce land occupation by 246.98 million m²·yr cropland-eq, although it would incur an increased freshwater usage by 1.26 million m³. Among the policy interventions assessed, extending infrastructure lifespan yields the most substantial long-term environmental benefits, outperforming strategies focused on increasing resource utilization or adopting advanced recycling technologies by around 2030.