A novel allocation method and critical transport distance for industrial by-products in concrete

Abstract

Cement production accounts for about 8% of global CO2 emissions, making it the largest industrial source in the construction material chain. Replacing cement with industrial by-products (IBPs) in concrete is a core pathway to reducing carbon footprint, but a scientifically sound allocation method is essential for accurately quantifying the carbon reduction contribution of IBPs. At present, the mainstream allocation methods in this field suffer from significant spatial and temporal fluctuations and low accounting stability, which seriously interfere with the accurate assessment of the carbon footprint and carbon emission reduction benefits of concrete incorporating IBPs. This study established an innovative production cost-based economic allocation principle for IBPs carbon footprints, which takes the manufacturing costs of primary industrial products and associated IBPs as the allocation core and considers their operational linkages within the industrial chain. Meanwhile, based on 929 groups of fly ash (FAH) concrete mix proportion data, a life cycle assessment approach was employed to systematically evaluate the carbon footprint characteristics of FAH concrete and quantify its critical transport distances (CTD). The findings indicate that the environmental impacts allocation principle and concrete mix design dominate the carbon footprint reduction potential and CTD of FAH. Low-carbon transportation equipment can significantly expand FAH’s CTD by reducing transport-related carbon footprint, which provides a scientific basis for the rational planning of large-scale promotion and efficient utilization of FAH. The proposed method offers a transferable methodological framework and may be adapted for carbon footprint accounting and carbon emission reduction contribution evaluation of other IBPs.