Success story: Eco-friendly breakwaters do double duty as welcoming homes for marine life

Concrete structures made to protect shorelines against erosion sometimes do so at a cost to local ecosystems. While they do armour the coast, they also change the physical environment. When made with conventional concrete, these structures leach acidic chemicals into the water. That said, new bio-enhancing concrete mixtures and block shapes offer the possibility of welcoming nature into these built environments, in areas that need them.

Tailor-made to support local ecosystems

ECOncrete , a marine technology company, has developed blocks made from an ecologically sensitive concrete mixture and shaped them to provide habitats for aquatic life. The company is working with the National Research Council of Canada (NRC) and the 加拿大渥太华大学 ? to study how well the blocks hold up against harsh sea conditions and higher water levels.

"Instead of being simple cubes, ECOncrete's blocks have all sorts of cavities and surface complexities," explains Scott Baker , Coastal Engineer at the NRC's?Ocean, Coastal and River Engineering Research Centre .

"There is one very large cavity that can become a cave underwater. That same cavity can also be oriented upwards to create a tidal pool. At high tide, the block may be completely submerged, but at low tide that little pool is going to stay filled with water," Baker explains, adding that holes passing through the blocks form small tunnels, offering hiding places for various sea creatures.

The blocks also have a specific texture to encourage marine life to bind to the surface. Baker says that after a few months in the ocean, life takes hold and the grey concrete colour of the blocks is no longer visible.

The NRC's facilities and expertise put the blocks to the test

By working with us, ECOncrete benefits from our research centre's?large wave flume facility? in Ottawa to physically test their blocks.

Baker has been working with Dogac Sayar , a University of Ottawa PhD student that he co-supervises with Prof. Ioan NISTOR , to study the performance and effectiveness of ECOncrete's blocks. Together, Baker and Sayar built a scale model breakwater armoured with replica blocks. They have used this physical model to test the blocks under a wide range of conditions, including varying water levels and wave heights. The team has also looked at how the spacing of the units, the size of rocks beneath the breakwater and the overall height of the structure affect the breakwater's stability.

Baker says these eco-friendly structures have the potential to be used along any coast in the world.

"We're going to continue building breakwaters for coastal protection into the future, but we also need to think about how we can integrate nature into our designs, and purposely use nature to our advantage."

"Anywhere we can work with nature is a plus. Where a completely nature-based solution is not possible, we want to ask ourselves: how can we enable the natural environment and a built structure to work together as effectively as possible? This project is a step in that direction." - Scott Baker, Coastal Engineer at Ocean, Coastal, River Engineering Research Centre

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