From concretes to bioreceptive concretes, influence of concrete properties on the biological colonization of marine artificial structures

International audienceA main cause of biodiversity loss is artificialization of the marine environment (IPBES 2019). With 39,400 km 2 of coastal and marine areas already encroached upon by human infrastructure and an increasing demand on space due to the growing global population – projected to reach 9 billion by 2050 – it is clear that humanity needs to find ways to prevent its activities from endangering biodiversity. To this end, since the 1990s ecologists have been trying to develop a win-win approach that unites ecological engineering with civil engineering. Today, civil engineers have a responsibility to incorporate eco-design processes in all construction projects underway to ensure that the latter benefit both humans and nature. Then, the new challenge of the 21st century is to develop eco-designed concretes that, in addition to their usual properties, provide improved bioreceptivity in order to enhance marine biodiversity without affecting the structure durability. The aim of this study is to master, clarify and classify the intrinsic parameters that influence the bioreceptivity (biocolonization) of cementitious materials in the marine environment. By using biofilm-culture-method (biofilm quantification), this study shows that the use of rough surface or slag cement CEM III and the surface treatment with green formwork oil enhance the biocolonization of cementitious materials in the marine environment whereas the application of curing agent (hydrophobic surface coating) has the opposite effect. Among the influent parameters, surface roughness proved to be the factor that promotes biocolonization most effectively