Life cycle assessment of concrete in artificial reefs: A case study of Køge Bay’s circle reef project.

Stone fishing, resource extraction and discharge of wastewater in Køge Bay, has influenced the local ecosystems negatively. The restoration project, Køge Bay Marine Park, plans to compare concrete and granite reefs to investigate similarities and differences between the two types of materials when used as (artificial) boulder reef. A framework was developed to assess the design of artificial reefs as tool for ecosystem creation, which includes categories like material properties, biological overgrowth etc. aiming to compare the performances of different concrete and cement types. The results of the framework have been incorporated in a comparative LCA to find the optimal concrete design. Multiple impact categories have been analyzed besides global warming impact to ensure a more complete analysis of different materials. The results of these comparisons highlight the importance of designing for lower amounts of cement in the reef units to decrease the environmental impact. The framework revealed a need for protocols for reporting essential information on both engineering and biological parameters. These aspects are of great importance in creating success criteria for coastal management.