Coastal marine ecosystems provide essential benefits and services to humanity, but many are rapidly degrading. Human activities are leading to significant land take along coastlines and to major changes in ecosystems. Ecological engineering tools capable of promoting large-scale restoration of coastal ecosystems are needed today in the face of intensifying climatic stress and human activities. Concrete is one of the materials most commonly used in the construction of coastal and marine infrastructure. Immersed in seawater, concretes are rapidly colonized by microorganisms and macroorganisms. Surface colonization and subsequent biofilm and biofouling formation provide numerous advantages to these organisms and support critical ecological and biogeochemical functions in the changing marine environment. The new challenge of the 21st century is to develop innovative concretes that, in addition to their usual properties, provide improved bioreceptivity in order to enhance marine biodiversity. The aim of this study is to master and clarify the intrinsic parameters that influence the bioreceptivity (biocolonization) of cementitious materials in the marine environment. By coupling biofilm (culture-based methods) and biofouling (image-analysis-based method and wet-/dry-weight biomass measurement) quantification techniques, this study showed that the application of a curing compound to the concrete surface reduced the biocolonization of cementitious materials in seawater, whereas green formwork oil had the opposite effect. This study also found that certain surface conditions (faceted and patterned surface, rough surface) promote the bacterial and macroorganism colonization of cementitious materials. Among the parameters examined, surface roughness proved to be the factor that promotes biocolonization most effectively. These results could be taken up in future recommendations to enable engineers to eco-design more eco-friendly marine infrastructure and develop green-engineering projects.

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The single-layer technique appeared at the beginning of the 1980s, with the ACCROPODE™ unit, and is thus entering its third decade. At the time, this solution was a real innovation, reducing the amount of concrete and steepening armour facing slopes, hence reducing the volume of materials required. After three decades in use and more than 200 projects to date, it was important to summarize the lessons learned during this period and to inspect (above and below water) some of these structures in order to assess their behaviour and particularly to confirm the validity of the unit placing rules. In addition to the aspects related to armour stability, the focus has been given to the colonization by marine life of the structures, including the bedding layers, toe berms, underlayer, armour units. The purpose of this paper is to share the experience gained throughout the inspections undertaken since 2010 on structures built more than 10 years ago. A large panel of structures has been inspected, of different ages and at various locations worldwide.

Dans certains cas l'utilisation d'enrochements n'est pas possible ou difficile à mettre en oeuvre. Ceci est en particulier dû : Soit à des houles de projet très fortes demandant des tailles d'enrochements significatives difficiles à produire en carrière ; et/ou soit à la distance entre la carrière et le projet impliquant une logistique et un surcoût important. Dans ces conditions la solution la plus usuelle est de considérer des éléments en en béton de type cube, tétrapode, ACCROPODE™ …. Le bloc ECOPODE™ entre pleinement dans le cadre des techniques monocouches. Il est donc plus économique que les solutions bicouches traditionnelles, et de plus il offre de part sa forme recherchée et une pigmentation possible une meilleur intégration dans l'environnement du projet. Le bloc peut-être économiquement viable en comparaison aux enrochements, du fait de la réduction des volumes de matériaux, de la méthodologie de fabrication/construction et d'un entretien très limité. Il est indéniable que le bloc ECOPODE™ est une alternative aux éléments préfabriqués en béton et dans certains cas aux enrochements naturels. La forme du bloc ECOPODE™ est très élaborée en comparaison aux blocs béton standard et demande une technique de coffrage particulière qui a fait l'objet d'études à CLI-Sogreah. La technique de coffrage obtenue suite à ces études consiste à utiliser deux coques en fibres de verre renforcées par une structure tubulaire en acier. Cette technique est actuellement mise en oeuvre sur le chantier d'Ospedalletti en Italie.

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