IN: Inspiration

Floating concrete islands

Architects build concrete structures to help restore coastal shorelines and ecosystems


Mangroves, the trees or shrubs that grow along tropical and subtropical coastlines, are vital for stabilising shorelines and preventing their erosion. However, the recent depletion of mangroves could negatively affect coastal habitats. 

In an attempt to address this, experts from the Cemex Research Group AG collaborated with architects from design firm APTUM to explore ways in which concrete could be used to restore and protect these trees and the areas in which they grow. By forging a symbiotic relationship with concrete and nature, the project, titled Rhizolith Island (Isla Rhizolith), seeks to combat the depletion of mangroves, specifically along the coast of Colombia.

“We took inspiration from the rhizolith: a root system encased in mineral matter that is created through processes of erosion and cementation that protects and strengthens the natural composition of the earth,” said Syracuse Architecture professors Roger Hubeli and Julie Larsen, partners at APTUM. “So our proposal for Isla Rhizolith is a breakwater system comprised of ‘root-like’ concrete elements and planted mangroves that, when set floating upon the water, act as both an artificial and natural rhizolith,” they added.

The Rhizolith Island was uniquely designed to restore the growth of mangroves in the area, reduce erosion of shorelines, prevent flooding and bring back life to  coastal ecosystems. The Rhizolith Island is constructed from two separate parts consisting of a ‘head’ and ‘fin’. The head was made using a lightweight concrete that is much lighter than water. The holes in the head’s design were added to dissipate water force during storm surges, thereby countering coastal erosion. The fin, which was made using a high-strength, ductile concrete, supports and provides shelter to the surrounding marine habitat. In this way, the Rhizolith Island offers a solution for both mangrove restoration and the restoration of life vital to coastal ecosystems.

While this is not the first project to use concrete technology as a means to protect shorelines, the Rhizolith Island is unique because it was designed to allow for a synthesis with the surrounding ecology. Within five to 10 years, it is expected that the increasing sedimentation will restore the shorelines and embrace the concrete structures; the mangroves growing on them will anchor in the newly deposited soil. “As the mangroves grow, their roots and weight will completely break through the concrete and take over to become a permanent, natural buffer to soak up water and reduce flooding during storms,” said the architects. “The structure’s broken down remains will promote the growth of coral reefs.”

“We are developing a solution that adapts to and is part of the behaviour of nature, rather than resists it,” said Davide Zampini, Head of Cemex Research Group AG. “Through the Rhizolith Island, we are taking a novel approach to address urbanization – the construction of building solutions that embrace, as well as strengthen, a symbiotic relationship with nature. The conceptualisation of cities will harness the resiliency that nature offers.”

The Rhizolith Island project was tested in Cartagena, Colombia, where a prototype was built and exhibited during the Concrete Reunion 2016 Conference. The data acquired is offering input for the construction of prototypes that will be tested further as the research continues at two additional locations in Colombia.

Images source: APTUM architects

Text source: ArchDaily


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