Material re-use

Material re-use is a cornerstone of circular economy principles in port sustainability. Re-using existing materials reduces demand for virgin resources, lowers embodied energy, and minimizes waste sent to landfill. Ports present unique opportunities for re-use, particularly with dredged materials. Maintenance and capital dredging produce large volumes of sediments, which can be repurposed for land reclamation, bund construction, habitat creation, or even processed into engineered fill materials. When appropriately treated and assessed for contamination, dredged material can replace imported aggregates, significantly reducing environmental impact.

Additionally, re-use can extend to structural elements such as reclaimed steel, concrete rubble used as armor rock, or repurposed infrastructure components. However, these approaches require careful quality assurance, environmental assessment, and design adaptation to ensure structural performance and regulatory compliance.

Materials selection is a critical component of green port development and long-term port sustainability. Within this discipline, material recycling and reuse play a central role in promoting circular economy principles, reducing environmental impacts, and improving resource efficiency. By prioritizing the recovery and repurposing of materials, ports can significantly reduce reliance on virgin resources, minimize waste generation, and lower embodied energy associated with construction and maintenance activities.

Material re-use is widely recognized as a cornerstone of sustainable port practice. Re-using existing materials reduces demand for raw extraction, decreases greenhouse gas emissions linked to material production, and diverts waste from landfill. Ports, due to their scale and ongoing maintenance activities, present unique opportunities to implement these principles at both operational and infrastructure levels. One of the most prominent examples is the reuse of dredged material (DM), which is generated in large quantities during capital and maintenance dredging operations.

Traditionally regarded as waste, dredged materials are increasingly being reframed as a valuable resource. When properly assessed and treated for contamination, these sediments can be repurposed for a wide range of beneficial uses (Solanki et al., 2023). Engineered applications include land reclamation, bund construction, shoreline protection, and beach nourishment. For instance, dredged material has been used successfully to support port expansion and coastal resilience by forming new landforms and reinforcing vulnerable shorelines (World Bank, 2025; USACE, 2024; USACE, 2023). Environmental applications are equally significant, with DM used in wetland restoration, habitat creation, and ecological enhancement projects, such as the construction of artificial islands and wildlife sanctuaries (see Nature based Solutions practice and beneficial re-use of dredged material practice).

In the context of green port development in DMCs, clay ripening provides a sustainable alternative to disposing dredged material offshore or in confined disposal facilities. The resulting clay can be reused locally for port expansion, land reclamation, dike construction, embankment strengthening and coastal resilience projects. Where the material is suitable and processing and transport impacts are assessed, converting a dredging by-product into a resource may reduce waste generation, transport requirements, carbon emissions and construction costs. The approach aligns with Building with Nature and circular economy principles by linking maintenance dredging activities with beneficial sediment reuse while supporting long-term environmental and infrastructure sustainability.

To enable these applications, treatment and conditioning technologies are often required. Techniques such as washing, sieving, grinding, stabilization, and calcination can improve the physical and chemical properties of dredged sediments. Washing can reduce chloride content, while stabilization and calcination can immobilize some heavy metals and activate mineral properties, which may make the material suitable for some construction uses, subject to testing. These processes can allow treated DM to substitute natural aggregates and, in some cases, partially replace cement in concrete production, contributing to lower-carbon construction practices.

Recycled and reused materials extend beyond dredged sediments. Ports routinely generate substantial quantities of construction and demolition waste, including concrete, steel, asphalt, and timber. These materials can be recovered and reused in new infrastructure projects. For example, crushed concrete rubble can be used as armor rock in coastal structures, while reclaimed steel can be incorporated into new builds (PIANC, 2014). Such practices not only reduce material costs but also decrease the environmental footprint of infrastructure development.

Transport infrastructure within ports also benefits from material reuse strategies. Treated dredged material and recycled construction waste can be used as fill material, subgrade, or base layers in road construction. When combined with additives such as lime, cement, or fly ash, these materials achieve improved strength and durability, enabling their use in high-performance applications. This reduces dependence on imported soils and aggregates, providing both environmental and economic advantages. Most commonly, dredged material is used for land reclamation, such as at the Port of Brisbane, reducing the need for offshore disposal.

Beyond engineering uses, recycled materials support broader sustainability goals, including land reclamation, landscaping, and agricultural applications. Treated dredged sediments can be used as soil amendments in urban redevelopment or brownfield restoration, contributing to land rehabilitation and improved soil quality (Solanki et al., 2023). Such approaches have been taken in the Netherlands, often referred to as ‘clay ripening’. In addition, lightweight aggregates derived from recycled materials can be used in green infrastructure, such as green roofs, enhancing water retention and urban climate resilience.

Despite the clear benefits, the adoption of recycling and reuse practices in ports faces several challenges. These include transportation costs, regulatory inconsistencies, and concerns related to contamination and material performance. Addressing these barriers requires robust quality assurance processes, comprehensive environmental assessments, and adaptive design approaches to ensure safety and compliance. Furthermore, stakeholder engagement, policy development, and education are essential to increase confidence in reused materials and promote wider uptake.

Many ports have already integrated recycling into their environmental management systems, setting measurable targets and monitoring progress. PIANC (2014, p. 34) described the Port of Antwerp’s AMORAS project and the Maritime and Port Authority of Singapore's sediment treatment initiatives as examples of how technologies and partnerships can turn waste streams into resources. The Maritime and Port Authority of Singapore (MPA) partnered with a local technology company to develop an award-winning technology to safely treat contaminated dredged materials and industrial waste and convert them into construction and reclamation materials. PIANC reported that this could reduce disposal and potential pollution issues arising from dredging and disposal of maritime related wastes such as oil sludge and copper slag (PIANC, 2014).

Material recycling and reuse are fundamental to sustainable materials selection in green ports. By leveraging innovative treatment technologies and embracing circular economy principles, ports can reduce environmental impacts while creating resilient, resource-efficient infrastructure systems.