Hydraulic Performance of Low-Crested and Emergent Breakwaters with Ecologically Designed Armor Units

Eco-friendly armor units and coastal structures provide a sustainable alternative to traditional design by incorporating eco-enhancing aspects into the design process to enhance biodiversity in their vicinity. ECOncrete’s Coastalock armor units feature a nature-inclusive design utilizing a bio-enhancing concrete mix, and biological surveys from a pilot deployment have already shown their positive impact in this sense. A comprehensive research program was initiated by the University of Ottawa and the Ocean, Coastal, and River Engineering Research Center of the National Research Council of Canada (NRC-OCRE), in collaboration with ECOncrete, a science-based bio-enhancing concrete technology company. Two-dimensional physical model tests of a low-crested and emergent rubble mound breakwater, each armored with Coastalock units, were conducted in the Large Wave Flume at the NRC-OCRE. Testing was conducted at a 1/15 scale. Both models were constructed as permeable structures with uniform 2V:3H front and back slopes and exposed to irregular waves with significant wave heights ranging between 0.08 and 0.38 m (1.2 and 5.7 m at prototype scale), while the wave steepness ranged between 0.03 and 0.07. This study focused on Coastalock armor unit placement, spacing, and underlayer rock size to understand their impact on hydraulic stability. The hydraulic performance of Coastalock armor units was analyzed by investigating wave transmission using existing formulas in the literature. Overall, the Coastalock armor units exhibited commendable stability against diverse wave conditions.