Cement types and seawater exposure in Europe – implications for infrastructure and its integration into marine habitats

In addition to the carbon footprint of construction materials, infrastructure in marine exposure has an environmental impact from construction processes and hardened waterfronts (ocean sprawl), which may amplify the biodiversity crisis. For artificial reef structures, different design approaches have been used and may also improve the integration of infrastructure into marine habitats to breathe life into ecosystems that are heavily influenced by human activity. Downsides of human activity are e.g., contaminants, noise, geometry, and textures that may be suboptimal for biogenic colonization and balanced ecosystems. One of the most reported materials for artificial reef structures is concrete due to its durability, the possibility to control its chemistry, and flexible use when it comes to geometry and surface textures. Hence, different cement types have been used and may yield somewhat different biological results, given equal biological conditions. At the same time, the regulations for the use of cement types for concrete in these exposure conditions differ between European countries, as concrete standard EN 206 is not harmonized. This article reviews the different cement types allowed in European standards for use in seawater exposure in selected European countries together with concrete design strategies of artificial reefs to highlight possibilities and limitations for the integration of infrastructure projects into existing habitats.