Opinion | Sustainable Roads Begin with Smarter Bitumen, Not Just Better Asphalt

As governments commit billions to rebuilding ageing highway networks while pursuing ambitious net zero targets, innovation in bitumen technology is emerging as one of the most effective ways to create roads that last longer, generate fewer emissions and make far better use of recycled materials.

When the conversation turns to sustainable highways, attention often focuses on electric construction plant, recycled aggregates or low-carbon concrete.

Yet one of the greatest opportunities to reduce the environmental impact of road construction may lie in a material that has formed the backbone of highway engineering for decades: bitumen.

Across Europe and North America, engineers are rethinking how asphalt is produced, modified and recycled. Rather than simply creating roads that are cheaper to build, the latest generation of bitumen technologies is designed to make pavements significantly more durable, reduce emissions during construction and maximise the reuse of existing materials.

The result is a shift away from traditional maintenance cycles towards infrastructure designed to remain in service for far longer while demanding fewer interventions throughout its lifetime.

The Greenest Road Is the One You Don't Have to Resurface

For highway authorities, sustainability is increasingly measured over the entire life of an asset rather than simply the carbon emitted during construction.

Every resurfacing scheme brings with it traffic management, congestion, emissions from construction plant, transport movements, material production and disruption to businesses and motorists.

Extending pavement life by even a few years can therefore generate environmental benefits far beyond the road itself.

That principle is driving interest in new bitumen technologies capable of dramatically increasing pavement durability.

One example is Gipave, developed by Italian specialist Iterchimica in partnership with graphene producer Directa Plus. The additive combines graphene with specially selected waste plastics that would otherwise be unsuitable for conventional recycling, creating a modified asphalt capable of withstanding significantly greater traffic loading.

Laboratory testing has shown the material can deliver up to 300% greater fatigue resistance and around 80% less rutting than conventional polymer-modified asphalt, potentially extending pavement life by two or even three times.

For road owners, that means fewer resurfacing cycles, lower whole-life costs and considerably less disruption over the lifetime of the network.

Turning Waste into Long-Term Infrastructure

One of the most compelling aspects of the latest bitumen technologies is their ability to incorporate materials that would otherwise become waste.

The plastics used within Gipave, for example, originate from hard polymer products that are typically unsuitable for conventional recycling streams.

Instead of ending up in energy-from-waste facilities, these plastics become part of longer-lasting highway infrastructure.

Research has also demonstrated that asphalt produced using the additive can itself be recycled at the end of its service life without creating additional harmful emissions, helping support a more circular approach to pavement construction.

This represents an important shift in thinking. Rather than viewing roads as assets that must eventually become waste, engineers are increasingly designing pavements capable of being renewed repeatedly with much of the original material remaining within the system.

Reducing Emissions Before the Road Even Opens

Sustainability is not solely about extending pavement life.

Reducing emissions during manufacture and construction is becoming equally important, particularly as urban authorities seek to improve local air quality.

To address this challenge, Hanson has developed its Reduced Emission Asphalt (REA) using Shell Bitumen's FreshAiradditive.

Trials have shown the technology can reduce emissions of nitrogen oxides, sulphur dioxide, volatile organic compounds, particulate matter and carbon monoxide by an average of around 40% compared with conventional asphalt production and paving.

Importantly, the technology can be combined with warm-mix asphalt and other low-carbon production techniques, creating opportunities to reduce both greenhouse gas emissions and local air pollution simultaneously.

For cities pursuing clean air strategies alongside decarbonisation, these technologies could become increasingly valuable over the coming decade.

Unlocking the Potential of Recycled Asphalt

Another major challenge for the highways sector is increasing the amount of reclaimed asphalt pavement (RAP) that can be successfully incorporated into new roads.

While recycling asphalt is already common practice, higher recycled contents have traditionally presented concerns around long-term performance.

Bio-based rejuvenators are beginning to change that equation.

Cargill's Anova, developed from modified vegetable oils, has demonstrated that asphalt containing around 45% recycled material can achieve performance comparable with conventional pavements while maintaining workability and durability.

Extensive trials on test facilities in the United States have shown encouraging results, suggesting significantly higher recycled contents can be achieved without compromising structural performance.

The implications are considerable.

Higher recycling rates reduce demand for virgin aggregates and bitumen while cutting the carbon associated with extracting, processing and transporting new materials.

A Different Way of Measuring Value

Historically, highway contracts have often focused on lowest initial cost.

Increasingly, however, clients are recognising that whole-life performance delivers much greater value.

An asphalt mix that costs slightly more on day one but lasts significantly longer can reduce maintenance expenditure, minimise congestion caused by roadworks and lower the lifetime environmental impact of an asset.

That broader definition of value aligns closely with the principles of sustainable infrastructure.

The most sustainable road is rarely the cheapest to build—it is the one that delivers decades of reliable service with the fewest maintenance interventions.

Engineering the Roads of the Future

As governments invest billions in renewing national transport networks, innovation in bitumen technology is quietly transforming what road sustainability means.

Graphene-enhanced asphalt, reduced-emission binders and bio-based rejuvenators demonstrate that future roads can be stronger, cleaner and far more circular than those built only a decade ago.

For highway authorities striving to balance climate commitments with growing traffic demands and constrained budgets, these technologies offer something increasingly rare in infrastructure delivery: solutions that improve environmental performance while also reducing long-term costs.

The future of sustainable roads may not depend solely on new highways—but on making every kilometre of existing highway last significantly longer.