Toward process-based inventory data for Portland clinker substitutes

The cement industry must produce lower carbon cements to meet its 2050 climate goals. A key low-cost strategy to achieve this is to substitute Portland clinker in cement with lower carbon materials. However, high-quality inventory data for clinker substitutes are poorly available, which limits the application of life cycle assessment (LCA) to quantify the carbon footprints of cements containing them. Here, we report the state-of-the-art inventory data for clinker substitutes, disaggregating them by unit process to facilitate comparison, improve proxy data selection, and identify gaps to inform future data collection efforts. Cradle-to-gate greenhouse gas emissions for European production of the clinker substitutes and carbon footprints of composite cements defined in EN 197 are calculated. Overall, we find the degree of clinker substitution, rather than the processing of clinker substitutes, is more impactful for producing low carbon footprint cements. This work can improve the transparency of LCA studies of concrete materials, verify commercial data, and inform technology development and business decisions related to the concrete value chain.