Lebanon’s coastline faces growing pressure from marine plastic pollution, while the country’s construction sector continues to depend heavily on natural resources such as sand and gravel. These challenges are usually treated as separate environmental problems. The Blue Stone: From Ocean to Architecture – Turning Marine Litter into Sustainable Solutions project explores how they can be addressed together.
A collaboration between the American University of Beirut (AUB) and the Lebanese NGO Cedar for Care (CFC), supported through a Small Green Innovative Projects (SGIP) grant, the project investigates how plastic waste collected from Lebanon’s beaches can be transformed into a useful material for construction.
From the Shore to the Laboratory
The process begins at Ramlet El-Bayda Beach in Beirut, where Cedar for Care organizes beach cleanups to collect discarded plastic, including food containers, drinking bottles, and other marine litter.
The collected material is then washed to remove soil, marine salts, and other contaminants before being manually inspected to remove materials such as metal fragments. At AUB’s laboratories, the plastic is shredded into fine particles that can be incorporated into concrete as a partial replacement for natural sand.
Researchers then test different concrete mixtures to understand how varying amounts of recycled plastic affect the material’s strength and performance. The aim is to find a balance between reducing the use of natural resources and maintaining the technical properties required for construction.
Finding the Right Balance
The research found that using fine plastic particles as a replacement for sand performed better than replacing larger gravel aggregates. Replacement rates of 5% to 7.5% were identified as an effective balance between sustainability and mechanical performance, while up to 12.5% can be suitable for applications where a moderate reduction in strength is acceptable.
Importantly, the tests also showed that incorporating plastic does not prevent concrete from continuing to gain strength over time. This opens possibilities for using recycled marine plastic in a range of construction applications.
From Research to Real-World Applications
The project has moved beyond laboratory testing through collaboration with South for Construction (SFC), exploring practical applications for the material.
One of these is the development of lighter masonry blocks, which can be used for partition and enclosure walls. Their reduced weight can make them easier to handle and transport while also reducing the overall dead load of buildings.
The project is also developing concrete panels for architectural finishes, cladding, and paving. By making the recycled material visible within the built environment, these products can demonstrate how waste can become part of new urban landscapes.
Future plans include developing elements such as public benches that could be installed directly in coastal areas, creating a visible connection between the waste collected from beaches and the materials produced from it.
Building a More Circular Economy
At its core, the Blue Stone project explores a circular approach to two resource-intensive systems. Plastic waste that would otherwise remain in the marine environment is redirected into construction, while the need for newly extracted sand and gravel is reduced.
Plastic-modified concrete can also be lighter than conventional concrete, potentially reducing transportation costs and contributing to lower building loads. Using recovered waste materials in place of mined aggregates can further create opportunities for more resource-efficient production.
The environmental benefits extend beyond construction. Removing plastic from Lebanon’s shores helps reduce the risks that marine litter poses to coastal and marine ecosystems, while recycling plastic into construction materials can provide an alternative to disposal or incineration.
Turning a Waste Problem into a Resource
The Blue Stone project demonstrates how environmental challenges can also become opportunities for innovation. By connecting beach cleanups, scientific research, engineering, and local manufacturing, the project brings together different parts of the environmental and construction sectors around a shared goal.
For Lebanon, where both marine pollution and pressure on natural resources remain significant challenges, approaches such as Blue Stone offer a practical example of how waste can be reimagined as a resource, and how local research and collaboration can help build more circular and sustainable systems.