Flash-calcined sediments versus raw sediments: A comparative life cycle assessment of SCMs

Abstract

The urgent need for reducing CO2 emissions and achieving sustainable development goals has prompted governments worldwide to adopt strategies such as Net-Zero targets for mitigating the environmental impact of various industries. Cement production, a major contributor to global emissions, has attracted significant attention due to its substantial carbon footprint. Simultaneously, the challenge of sediment disposal poses a pressing environmental concern. This study focuses on the environmental sustainability of cement and mortar production, particularly through the incorporation of dredged sediments as supplementary cementitious materials (SCMs). This research addresses a knowledge gap regarding the sustainability of flash calcined sediments (FCS) versus dried ground sediments (DGS) as SCMs. Using life cycle assessment (LCA), it examines their environmental performance, benefits, drawbacks, and the impact of sediment treatment. This approach sets it apart from prior research solely focused on the substitution effect of ordinary Portland cement (OPC). Substituting OPC with FCS/DGS sediments at 5–30% can reduce CO2 emissions by 6.44–15.51% with respect to the 52.5 MPa equivalent cement functional performance. FCS scenarios have shown a lower Global Warming Potential (GWP) than observed in cement with DGS except at a substitution rate of 15%. The study also highlighted the influence of cement functional performance, fuel type, and flash calcination techniques on the overall environmental performance. For mortar assembly, the findings revealed that utilizing FCS for 30% substitution of OPC has more environmental saving benefits than using DGS. Cement production, as well as the leaching behavior of trace elements, significantly affect the toxicity to ecosystems and human health categories. Future research should address the full burdens of sediments and develop appropriate allocation factors to accurately assess their environmental impact, especially if their classification shifts from waste to a valuable resource. This will ensure a comprehensive evaluation with respect to their effects on marine ecosystems and navigation improvement.