Living Seawalls: How They’re Bringing Sea Life Back into Busy Urban Areas with the Help of Some Slag

LIVING SEWALLS LIVING SEWALLS

HOW THEY’RE BRINGING SEA LIFE BACK INTO BUSY URBAN AREAS WITH THE HELP OF SOME SLAG.

It's not every day you stumble across a project that uses concrete panels to encourage sea life back into urbanised harbours... Yes, that's right, concrete.

It seems that in recent years, concrete has been given a spotlight in the media that not been very positive whatsoever. As the world's most used material second to water, the manufacture of concrete, in particular cement, results in large amounts of carbon dioxide being emitted. Many ENGO’s across the world label concrete as ‘climate’ a problem. But what if it's the solution?

The Australasian (iron & steel) Slag Association mission is to expand the effective and beneficial use of iron and steel slags. Various forms of Slag can be used to manufacture concrete to reduce the amount of cement and natural aggregates in the mixture (which is better for the environment). Technically, its’ common knowledge that including slag in concretes increases workability, durability, and water tightness, providing benefits to all those who choose to utilise this SCM. The team at Living Seawalls recognise the opportunity to utilise these resources to make an environmental impact. Back in November, the Australasian (iron & steel) Slag Association had the chance to sit down with Aria Lee (Research Assistant) and Alex Goad (Director and Industrial Designer) from Living Seawalls to learn more about this project.

At Living Seawalls, it is clear the team is trying to change the way we think about building in the ocean. Specifically, instead of building structures that are damaging sea life- what if we could give back to life under the sea?

Living Seawalls has been operating for the past three years though is a product of over 20 years’ worth of scientific research. As a result of this research, the organisation identified a large problem and worked to find a solution.

THE PROBLEM:

Seawalls are a dominant feature in urbanised areas around the world. All you must do is go to Sydney Harbour to witness where the property meets the sea. To ensure the structural integrity of these great edifices, seawalls are common.

The problem is that seawalls pose a threat to marine life, which are vital in providing a range of ecosystemic functions. The habitat that seawalls provide is vastly different from natural foreshores. Natural shores typically consist of several microhabitats, such as crevices, cavities, pools, boulders, and overhangs that support the recruitment of marine life (such as barnacles, seaweed, oysters and more). Seawalls are typically the opposite- smooth surfaces that deflect anything that comes upon it. Not only this, but the material type, roughness, porosity, and chemical composition of the substrate also differ between seawalls and natural shores. This would only naturally affect the habitation in this area.

THE SOLUTION:

Having been based on over 20 years of research, Living Seawalls set out with a mission to conjure a solution that benefits all parties. It became evident almost immediately that there's no stopping the construction of seawalls or in fact, the construction boom. The global extent of these marine built structures is significant, cumulatively covering 32,000 km2

Living Seawalls in conjunction with a precaster have formed what Alex Goad describes as an "Eco blend" concrete mixture featuring slag, fly ash and other SCMs (such as ground shells) to curate a concrete panel that mimics natural rock formations. In total, there are 10 different 'Habitat panel' designs aiming to attract different species per panel. The panels are formed by precasting in a 3D printed mould designed by project partner, Reef Design Lab (directed by Alex). Following a series of tests, these panels are then sent out to fulfil their purpose. Successful test completion saw the seawall panels able to withstand up to 2 tonnes of pressure while still maintaining structural integrity.

In future, Alex told the ASA that he's open to experimenting with more recycled materials, providing it is safe to do so. Some PhD students are also experimenting with coloured concrete to see if colours impact the habitation on certain panels, leaving room for further development.

WHY WE SHOULD CARE?

Research Assistant Aria Lee says that the support of the construction and building industries can make all the difference. Implementing simple strategies like Living Seawalls allows for a sustainable solution for marine life that has been impacted.

In an interview with the Australasian (iron & steel) Slag Association, Ms Lee said, "I'd just like to stress this is the sector that can push forward change... Building multifunctional structures makes sure we give back to the environment," she said.

Living Seawalls is changing the face of marine construction and conservation one panel at a time. Being an Earthshot Prize Finalist in 2021, this organisation still has so much to give.