Scientists at City University of Hong Kong (CityU) are creating new eco-friendly marine structures that support the settlement and growth of marine organisms and lower sea temperatures to enhance biodiversity.

The CityU team has created an award-winning two-fold innovation. First, an eco-friendly concrete mix comprising 40 percent waste materials has been developed. The mix includes fly ash from the incineration of sludge and dredged marine sediment typically taken from routine maintenance carried out on regional shipping lanes. This concrete mix’s high compressive strength (39 MPa) and low surface pH (about 10) are crucial for sea defense structures and marine larval settlement.

Second, microhabitats, such as grooves, holes and crevices embedded in the CityU team’s eco-tiles, offer refuge for marine life and shade that can lower temperatures during low tide in summer. Twelve-month trials conducted in Hong Kong waters demonstrate that these eco-tiles reduce the average surface temperature by 2° C and increase biodiversity by 80 percent compared to conventional seawalls.

In addition, a CityU startup called afterNATURE is working on a range of eco-engineered products, including eco-tiles, eco-panels, tidal pools and eco-blocks. These products have already been adopted at numerous local seawalls in Hong Kong and have gained traction in coastal restoration projects in South Korea, mainland China, and the United States.

Learn more here.