Investigating the material intensity of China's infrastructures using bill of quantity (BoQ)

Infrastructures provide essential services but demand massive material inputs and generate substantial solid waste and embodied carbon emissions. Circular economy strategies offer a promising mitigation pathway by promoting infrastructure material circularity. The promotion requires understanding infrastructure material stock and flow, which depends on material intensity coefficient (MIC)-based stock-flow quantification. Yet, reliable infrastructure MICs remain scarce in existing literature. This study develops a standardized framework for compiling the real bills of quantities (BoQs) to derive MICs. Applying the framework in 181 infrastructure projects in China derived the robust MIC distributions of roads, railways, pipelines, cable systems, and flood control levees across distinct engineering grades. Also, material composition analysis indicates a “concrete-base aggregate-steel” dominance across these infrastructure cohorts, with average shares of approximately 61.5% concrete, 22.4% base aggregates, and 6.1% steel. Furthermore, comparative analysis reveals that previous studies underestimate infrastructure material intensities by up to an order of magnitude, due to the available MICs omitting structurally intensive components (e.g., viaduct structures and tunnel structures) and certain materials (e.g., asphalt). This research contributes a more reliable and extensive MIC dataset for China's infrastructures, while demonstrating a standardized BoQ-based MIC quantification framework. The MIC dataset provides empirically grounded references for infrastructure material stock-flow and embodied environmental impact assessment, and contributes robust data to support infrastructure circularity promotion. • Reliable infrastructure material intensity data is crucial yet limited. • BoQs from 181 projects used to quantify infrastructure material intensity. • Robust intensity data (t/km) for roads, rails, pipelines, cables, and levees. • Infrastructure averages: 61.5% concrete, 22.4% aggregates, 6.1% steel. • Prior studies significantly underestimated China's material intensities.