Kajima develops Circular Plus Pavement with construction-site waste plastic

Construction waste plastic extends road lifespan and cuts emissions

A new pavement technology from Japanese construction firm Kajima demonstrates how waste plastic from building sites can strengthen road surfaces while reducing carbon emissions. The system addresses two infrastructure challenges at once: shorter pavement replacement cycles and the disposal of construction plastic waste.

Kajima’s Circular Plus Pavement uses plastic recovered from construction sites to extend road lifespan and lower lifecycle carbon dioxide emissions. Longer replacement cycles mean fewer materials, less disruption, and reduced maintenance spending over time. For businesses managing commercial property or industrial sites, that translates directly to lower ownership costs.

The technology aligns with a wider shift across road construction. Recycled plastic is now being tested and deployed in asphalt mixes because it improves durability and diverts waste from landfill. What was once experimental is becoming standard practice in several countries, particularly where waste plastic volumes justify the investment in processing infrastructure.

Kajima’s sustainability reporting emphasizes carbon reduction and environmental management goals. The pavement product fits that strategy by tackling emissions and material waste simultaneously. For UK firms tracking Scope 3 emissions or responding to public procurement sustainability criteria, these combined benefits matter.

Plastic waste in road construction is established practice

Using waste plastic in road surfaces is not new. Several countries have incorporated it into bituminous mixes for years, typically through dry or wet processing methods. Official guidance from India’s Ministry of Road Transport and Highways describes both approaches in detail.

The dry process involves coating aggregate with shredded plastic before adding bitumen. This method is being used in national highway projects across India. The wet process blends plastic directly into bitumen before mixing with aggregate, but quality concerns have limited its adoption.

Research confirms that plastic can improve specific pavement properties when blended correctly. Studies report better shear resistance, increased stiffness, and higher load-bearing capacity. These are not marginal gains. They affect how long a road lasts under heavy traffic and how well it resists deformation.

One technical review concluded that adding around 5% plastic waste to asphalt mixes optimizes performance without harming viscosity. UK government laboratory tests indicate that 5% to 10% shredded waste plastic by weight of bitumen works well, with 8% recommended as optimal in some applications. Dow Chemical reports that polymer-modified asphalt using postconsumer recycled plastic can replace nearly 10% of bitumen and generate lower greenhouse gas emissions.

Longer pavements reduce total lifecycle emissions

The environmental case for plastic-modified pavements rests on lifecycle thinking. Traditional asphalt requires regular resurfacing or replacement, often every 10 to 15 years depending on traffic and climate. Each replacement cycle involves materials extraction, manufacturing, transport, and installation. Those activities generate carbon emissions and incur costs.

Extending pavement life reduces the frequency of those interventions. If a road lasts 20 years instead of 12, the total emissions and costs drop even if the initial installation is slightly more expensive. Maintenance becomes a smaller proportion of whole-life spending.

For UK businesses, this matters in two contexts. First, companies managing large sites or logistics facilities face ongoing pavement maintenance costs. Longer-lasting surfaces reduce budgeting pressure and minimize operational disruption. Second, organizations reporting carbon footprints under PPN 06/21 or similar frameworks must account for Scope 3 emissions from purchased goods and services. Choosing lower-carbon materials helps meet those reporting requirements.

Construction-site waste plastic adds another dimension. Building projects generate substantial plastic waste from packaging, protective sheeting, and temporary materials. Diverting that waste into road construction creates a use case that reduces disposal volumes and avoids virgin material extraction. The result is a materials loop that keeps plastic in circulation rather than sending it to landfill or incineration.

Technical constraints determine real-world performance

The environmental promise of recycled-plastic pavements depends on execution, not just the concept. Technical guidance stresses that plastic type, particle size, temperature control, and contamination levels are critical for safe and reliable performance.

Indian road construction guidance warns that plastics should not be heated above 180°C during processing. Excessive temperatures can degrade the plastic and release harmful fumes. Only certain plastic types are suitable for use in asphalt, typically polyethylene and polypropylene. Mixed or contaminated plastic can compromise pavement quality and create environmental risks.

Particle size also matters. Plastic must be shredded to a specific size range to coat aggregate evenly in the dry process or blend smoothly in the wet process. Too large, and it won’t distribute properly. Too small, and it may not provide the mechanical benefits that justify its use.

These constraints mean that successful deployment requires careful material sorting, processing infrastructure, and quality control. For businesses considering recycled-plastic pavements, that means working with contractors who understand the technical requirements and can demonstrate compliance with relevant standards.

What this means for UK businesses and infrastructure planning

• Waste plastic from construction sites can be recovered and used in pavement materials, reducing disposal costs and carbon emissions.
• Research suggests that adding 5% to 10% plastic waste by weight of bitumen improves pavement durability without harming performance.
• Longer pavement replacement cycles lower total lifecycle costs and reduce disruption to operations.
• Polymer-modified asphalt using recycled plastic can replace nearly 10% of virgin bitumen and cut greenhouse gas emissions.
• Technical success depends on plastic type, particle size, temperature control, and contamination management during processing.
• The approach supports carbon reporting requirements and public procurement sustainability criteria.

Materials circularity meets decarbonization in infrastructure

Kajima’s approach connects two infrastructure priorities that are increasingly linked in UK policy and procurement. Decarbonization targets focus on reducing emissions across the built environment. Materials circularity aims to keep resources in use and minimize waste. Recycled-plastic pavements address both.

For businesses responding to local authority procurement requirements or qualifying for public sector contracts, this dual benefit is significant. Many tender processes now include carbon reduction and circular economy criteria. Demonstrating lower lifecycle emissions and waste diversion can improve scoring in competitive bids.

Construction projects generate plastic waste at every stage, from groundworks to fitout. Finding productive uses for that waste reduces disposal costs and environmental impact. However, the solution must be technically sound and economically viable. Recycled-plastic pavements meet those tests when properly specified and installed.

The technology also aligns with broader sustainability frameworks that UK businesses are adopting. Organizations working toward net zero or reporting under the Task Force on Climate-related Financial Disclosures need to reduce emissions from materials and construction activities. Choosing pavement materials with lower carbon intensity and longer service life contributes to those goals.

Moreover, businesses with large property portfolios or logistics operations face ongoing infrastructure maintenance. Roads, yards, and access routes deteriorate under traffic and weather. Planning for longer replacement cycles reduces capital expenditure and minimizes operational disruption. That makes recycled-plastic pavements a practical option, not just an environmental statement.

Industry momentum and regulatory context in the UK

The UK government has published guidance on using recycled materials in highways, including plastic waste. Laboratory testing has informed recommended dosage rates and processing methods. Although adoption in UK road construction is not yet widespread, the regulatory framework supports innovation in pavement materials.

Several councils and highway authorities have trialed plastic-modified asphalt on local roads. Results have been mixed, with some projects reporting improved durability and others encountering technical challenges. Success appears to depend on contractor expertise, material quality, and site conditions.

Regulatory pressure is increasing. The government’s environmental reporting guidelines require large companies to disclose greenhouse gas emissions. The Procurement Policy Notes, particularly PPN 06/21, set carbon reduction expectations for public sector suppliers. These frameworks create commercial incentives to adopt lower-carbon materials and processes.

Businesses supplying infrastructure projects or managing large sites should monitor how these policies develop. As carbon reporting becomes mandatory for more organizations, the lifecycle emissions of pavement materials will come under closer scrutiny. Choosing materials with verified carbon savings will become a competitive advantage.

Planning for longer pavement lifecycles

For UK businesses evaluating pavement options, the key questions are lifecycle cost, performance, and carbon impact. Recycled-plastic pavements offer potential benefits in all three areas, but only if properly designed and installed.

Start by assessing current pavement replacement cycles and maintenance spending. If resurfacing happens every 10 years, extending that to 15 or 20 years delivers measurable savings. Calculate the total cost of ownership, including materials, labor, and operational disruption. Compare that to the cost of a longer-lasting pavement with higher upfront investment.

Next, consider carbon reporting obligations. If your organization reports Scope 3 emissions, pavement materials are part of that calculation. Lower-carbon options reduce your reported footprint and support net-zero commitments. SBS offers compliance support for businesses navigating carbon reporting requirements and seeking to reduce emissions across their supply chains.

Technical due diligence is essential. Ask contractors about their experience with recycled-plastic pavements, the source and quality of waste plastic, and compliance with relevant standards. Request evidence of performance in similar applications. Poor execution can undermine the environmental and economic benefits.

Finally, think about waste management across your operations. Construction projects generate plastic waste that currently goes to disposal. Diverting that waste into pavement materials closes the loop and reduces disposal costs. Work with contractors who can manage waste plastic recovery and processing as part of the project scope.

Where to find detailed guidance and standards

The Department for Transport provides policy direction on sustainable highways and infrastructure materials. Although specific guidance on plastic-modified asphalt is limited, the department’s sustainability framework supports innovation in lower-carbon construction methods.

The Chartered Institution of Highways and Transportation publishes technical guidance on pavement design and materials. Members can access research and case studies on recycled materials in road construction.

For businesses seeking to reduce carbon emissions and improve materials circularity, SBS supports organizations with carbon reporting, supplier engagement, and sustainable procurement strategies. We help businesses meet compliance requirements and identify practical opportunities to reduce environmental impact across their operations.