ECOncrete’s CEO Ido Sella presents his company’s sustainable approach to marine construction projects that use concrete.
Approximately 70% of the world’s man-made marine structures - jetties, breakwaters, harbour walls and sea defences - are built using concrete. However, such structures do not capture ecosystem services or support diverse marine life, such as many water-filtering species. This leads to poor water quality and low levels of biological activity. Foreign materials such as standard concrete frequently lead to a dominance of invasive species from far away, brought in on ships’ hulls or in ballast water. The invasive species rapidly colonise the structure and shut out opportunities for native species, which leads to poor biodiversity and ecosystem functioning.
As a marine biologist all too aware of the impacts of traditional concrete on marine ecosystems, I founded ECOncrete in 2012 with my colleague Dr Shimrit Perkol-Finkel. The company would investigate ways to enhance the biological performance of concrete structures in the marine environment. This was not a straightforward task but one we felt compelled to take on, as the issues surrounding the use of concrete in the marine environment will only become more pertinent as sea levels rise due to climate change. There will be a need for vast quantities of concrete to protect the coastlines of the future. Maintaining biodiversity is also crucial in the fight against the worst effects of climate change. We envisioned that new concrete structures should support marine species as much as possible while preventing continued biodiversity loss. At the same time, it is desirable for such structures to be as resilient as possible, with lifetimes in excess of 100 years.
The ECOncrete approach
In its early stages, ECOncrete tested a wide range of high-performance concrete mixes to investigate the conditions that would encourage marine species, particularly corals, oysters, barnacles and mussels, to colonise the surface. It was found that successful colonisation required a mixture of chemical, micro-structural and macro-structural properties.
Chemical: The chemical properties of concrete determine whether or not oyster larvae, for instance, will be able to colonise the surface. Most modern concrete mixtures, which contain a large number of retarders, plasticisers, accelerators, and so on, are fairly hostile to the development of marine life.
ECOncrete has patented admixtures / extenders, one for sea water and one for fresh water. Both actively promote the development of marine life. These are dosed to the concrete mixture at 10% by weight. For a typical 1m3 block of concrete made using 350 - 400kg of cement, there would typically be 30 - 40kg of ECOncrete’s admix. Both of the patented admixtures are 80%-derived from fine natural byproducts from other sectors that would otherwise go to landfill. They are currently made in Israel, although ECOncrete is in the process of expanding this capability into Europe and the US.
Micro-structure: Once the larvae come into contact with a concrete surface that is suitable from a chemical perspective, the surface microstructure comes into play. ECOncrete’s surfaces, which have structures from the nano-scale up to a few millimetres across, have many potential sites available for colonisation, meaning that lots of larvae will take up residence. Only a proportion will make it to adulthood, but the coverage will be a lot higher than in untreated concrete. To provide the microstructure, ECOncrete produces liners for moulds, or uses a proprietary texturising agent. For example, in a recent project in Florida, US, the client purchased admixture and ECOliners that fitted into its existing pile moulds.
Macro-structure: Once the surface has been colonised with ecosystem-engineering species, larger structures come into play. Niches can be included as habitat for various species of fish and, for tidal areas, infrastructure can include water-retaining pools that function much like natural tidepools. There can be niches for the initial fish and ecosystem engineering colonisers and, as the ecosystem evolves from sedentary filter feeders like oysters, to juvenile fish, shrimps and hunters like starfish, there are plenty of spaces to support species up the food chain and to encourage a healthy ecosystem.
The benefits
There are several benefits to using ECOncrete:
Maintaining biodiversity: Biodiversity loss as a major threat to a functioning planet. When we have low biodiversity, we get unhealthy ecosystems, which in turn, can’t provide us with essential services like food, flood protection, carbon storage, clean water, and more. When a structure is built with ECOncrete, the biology that colonises that structure will be the close to that found in the surrounding natural environment, and much more representative of a natural ecosystem than traditional infrastructure. This supports local biodiversity, which is good not only for the species in question but also for the health of the planet in general.
Bioprotection: Concrete that is covered with sedentary organisms that have hard, calcium carbonate shells is strengthened compared to concrete that is not covered. The biological layer buffers the concrete from temperature changes between the water and the concrete surface, leading to fewer cracks.
As these organisms, like corals, barnacles and oysters, have shells made of calcium carbonate, they also strengthen the surface by impregnating it with calcium carbonate, effectively gluing it together. The biological structure can even be stronger than the concrete itself. Research by North California University compared standard concrete bars to those that had been colonised by oysters for two years. The tensile strength of the oyster-encrusted bars had increased by a factor of 10. Chloride penetration is also greatly reduced by colonisation of these types of species.
Carbon sink: As they form their shells, oysters, barnacles, mussels and corals remove calcium and CO2 from seawater and convert it to calcium carbonate. By doing this, they function as an active carbon sink. When they die, the oysters’ shells, for example, fall to the seabed and the carbon is captured indefinitely. The next generation of oysters can then grow in their place. Via this mechanism, a 1km sea wall built using ECOncrete’s technology sequesters the same amount of CO2 every year as 100 trees. This is a major additional advantage compared to building with conventional concrete in the marine environment.
Cost reduction: ECOncrete’s technology has a substantial return on investment. The process of casting and installing elements is identical to using normal concrete. At the project level, the ECOncrete system is cost competitive. Adding 10% of ECOncrete’s admix, admixtures, and liners has a slightly higher price tag than traditional technologies, but comes with multiple and more significant savings at the project level.
This is because of large permitting and mitigation costs. For example, the company is currently engaged in a US$75m project to build eight ecologically-designed breakwaters for the state of New York. To build these using standard concrete or quarry rock, the state would be faced with an environmental mitigation cost of US$18m. However, by incorporating ECOncrete’s technology, the environmental benefits of the overall design and the concrete infrastructure reduce the mitigation costs to US$4m.
The future
Thanks to these advantages, ECOncrete has seen great expansion in recent years. The company expects to produce eight times as much ECOncrete for marine structures in 2021 compared to 2020. This is expected to double again in 2022.
Larger projects, such as the New York breakwaters, represent an exciting foray into larger projects for ECOncrete. The company is involved in pipeline armouring in the Black Sea and shoreline reinforcements in the Port of San Diego in the US. In the coming years, ECOncrete will scale up its focus on the offshore sector, with a particular focus on the wind power sector. This area will see a step-change in the coming decade, particularly in the North Sea and off the north east coast of the US. The company’s solutions can be used to protect the seabed around the base of monopiles used to construct wind turbines. This protects them from scour, so that the currents do not erode the region around the base of the turbine, while regenerating local biodiversity. This may also require the use of ECOncrete articulated concrete block mattresses to protect the underwater cables. ECOncrete is working with Holcim in this area right now. There is also great potential to use ECOncrete’s system to form the edges of new land reclamation projects.
ECOncrete is now at a point of rapid growth and the company sees great opportunities to use its technology to build a better marine environment over the coming decades.