Low Carbon Materials

Low-carbon materials are becoming a critical component of green port development as ports seek to reduce not only operational emissions but also the embodied carbon associated with infrastructure construction. Port assets such as wharves, quay walls, seawalls, breakwaters and terminal facilities require large volumes of steel and concrete, making material selection an important factor in achieving sustainability objectives (PIANC, 2019).

Rather than replacing traditional materials entirely, the industry is increasingly adopting lower-carbon alternatives. Green steel, produced using renewable electricity or hydrogen-based technologies, can significantly reduce emissions compared with conventional steelmaking. Similarly, low-carbon concrete incorporates supplementary cementitious materials (SCMs), such as fly ash, ground granulated blast furnace slag (GGBFS) and calcined clays, which reduce reliance on carbon-intensive cement clinker. Emerging carbon capture and storage technologies within cement production further support emissions reduction (Global Cement and Concrete Association, n.d.).

Innovative materials are also gaining traction. CO₂-mineralized concrete stores captured carbon dioxide within the concrete matrix as stable minerals. Its planned use at Singapore’s Tuas Port, with a supplier-estimated avoidance of more than 113.8 million kg of CO₂, illustrates the potential for embodied carbon reductions in maritime infrastructure (Pan-United, 2023).

Alternative materials such as geopolymer concrete, fiber reinforced polymer (FRP) composites, recycled plastics and hybrid composite systems offer additional opportunities to reduce emissions and support circular economy outcomes. Some of these materials can provide good corrosion resistance and reduced maintenance requirements in marine environments, depending on the product and exposure (PIANC, 2009).

While challenges remain regarding structural capacity and long-term performance, a hybrid approach is increasingly being adopted. By combining life-cycle thinking, material efficiency, recycled content and innovative low-carbon materials, ports can substantially reduce embodied carbon while maintaining the resilience, safety and durability required for long-term maritime infrastructure (PIANC, 2014; PIANC, 2019).

The transition to green ports is increasingly focused on reducing the embodied carbon associated with port infrastructure. While operational emissions from ships, vehicles and equipment remain important, the materials used to construct quays, wharves, seawalls, breakwaters and terminal facilities can represent a significant share of a port’s lifetime carbon footprint. Guidance from PIANC (PIANC, 2019) emphasizes that material extraction, manufacture, transport, construction, maintenance and end-of-life treatment should all be assessed using a life-cycle perspective when pursuing sustainable port development.

Ports have traditionally relied on steel and concrete because of their strength, durability and ability to withstand harsh marine environments. However, these materials are also major contributors to embodied carbon. Steel and concrete production account for a large share of construction-related emissions, making them key targets for decarbonization initiatives (PIANC, 2019).

Rather than replacing these materials entirely, the industry is increasingly adopting lower-carbon alternatives. Green steel, produced using electric arc furnaces powered by renewable electricity or hydrogen-based processes, can significantly reduce emissions compared with conventional blast furnace production. Likewise, the carbon intensity of concrete can be lowered through supplementary cementitious materials (SCMs), including fly ash, ground granulated blast furnace slag (GGBFS) and calcined clays, which reduce reliance on high-carbon cement clinker. Emerging carbon capture and storage (CCS) technologies in cement manufacturing (Global Cement and Concrete Association, n.d.) offer additional opportunities to reduce emissions while maintaining the performance required for critical maritime structures.

In February 2023, Pan-United announced planned supply of approximately 360,000 m³ of CO₂-mineralized concrete with green cement for Tuas Port over 2.5 years. The company estimated that the combined supply would avoid more than 113.8 million kg of CO₂ emissions, which it equated to planting 1.9 million trees or removing 24,500 cars from the road (Pan-United, 2023). This forecast is not a measurement of CO₂ stored in the concrete or confirmation of completed delivery.

Material optimization is equally important. PIANC’s carbon management guidance (PIANC, 2019) highlights reducing material quantities through efficient design, prefabrication, reuse of existing assets and incorporation of recycled content. Environmental Product Declarations (EPDs) are increasingly used to compare embodied carbon performance and support sustainable procurement decisions.

Beyond lower-carbon versions of traditional materials, ports are also assessing alternative materials that may further reduce embodied emissions. Geopolymer concrete is among the most promising. By replacing Portland cement with binders such as fly ash and GGBFS, geopolymer concrete can reduce embodied carbon, depending on the binder, activator and mix; marine durability must be demonstrated for each mix and exposure. The Port of Rotterdam trial is described in the case study below.

Australian research has trialed geopolymer concrete for heavy maritime applications. Mahmood et al. (2018) and Mahmood, Foster and Castel (2020) describe a high-density geopolymer concrete developed by UNSW and industry partners for breakwater armor units exposed to severe wave conditions.

This material combines steel furnace slag (SFS) aggregate with a fly ash-blast furnace slag binder, addressing challenges associated with steel slag aggregates. Field trials at NSW Ports’ Port Kembla Harbor provided performance data. A three-year follow-up found no spalling in splash-zone units, but strength loss and spalling in field-batched specimens air-cured in the laboratory (Mahmood, Zahid and Foster, 2025). The research found that SFS aggregate increases concrete density, improving structural mass and stability while potentially reducing armor unit size. By repurposing industrial by-products, the material can reduce embodied carbon, diverts waste from landfill and supports circular economy outcomes. Smaller armor units could also lower transport, construction and associated emissions (Mahmood et al., 2020).

Polymer-based materials and composites represent another area of innovation. PIANC’s guidance on alternative marine construction materials (PIANC, 2009) notes increasing use of recycled plastics, fiber reinforced polymer (FRP) composites and hybrid systems in marine infrastructure. These materials offer strong corrosion resistance, low maintenance requirements and long service lives in aggressive marine environments. Many products incorporate recycled plastics and reclaimed fibers, contributing to circular economy objectives while reducing greenhouse gas emissions.

Examples include:

• FRP sheet piles
• composite decking
• structural components
• fender systems
• glass fiber reinforced polymer (GFRP) reinforcement bars.

GFRP reinforcement is particularly attractive in marine applications because it is non-corrosive, lightweight and has a high strength-to-weight ratio (PIANC, 2009). These characteristics can extend asset life and reduce maintenance and replacement requirements.

Other emerging materials include timber composites, recycled polymer products and engineered hybrid systems designed to optimize durability and sustainability outcomes. Such materials are increasingly used in walkways, pontoons, marinas and secondary infrastructure where lightweight construction and corrosion resistance provide important advantages.

Despite their benefits, alternative materials face challenges, including lower structural capacities than steel or reinforced concrete, limited long-term performance records and uncertainty under sustained marine exposure. As a result, most ports adopt a pragmatic hybrid approach. Low-carbon concrete and steel remain the preferred options for major load-bearing structures, while alternative materials are typically used in non-critical applications such as decking, fenders, walkways, utility structures and rehabilitation projects.

Ultimately, low-carbon materials are becoming a cornerstone of green port strategies. By combining life-cycle thinking, material efficiency, low-carbon variants of traditional materials, recycled content and innovative composite technologies, ports can significantly reduce embodied carbon while maintaining the resilience, safety and durability required for long-term maritime infrastructure (PIANC, 2014)