Application of low carbon concrete
Scaling the application of low carbon concrete and fibre reinforced polymer reinforcement in highway structures
This project addresses the National Highways challenge of accelerating the adoption of low-carbon construction materials by developing practical pathways for the use of fibre reinforced polymer (FRP) reinforcement and low carbon concretes, (specifically alternative binder system (ABS) concretes), in highway structures. Current UK standards provide limited coverage for these emerging technologies, creating barriers to their wider deployment and exploring their potential carbon, durability and whole-life performance benefits.
The project comprises two principal workstreams:
FRP reinforcement
- Development of generic design and material departures from standards.
- Design of FRP-reinforced precast structural components, including an L-wall, ( L-shaped vertical retaining walls).
- Identification of technical evidence requirements for wider deployment.
Low carbon concretes
- Assessment of ABS concretes against BSI Flex 350 requirements, (which deals with how to assess concretes that can lower carbon emissions while maintaining performance).
- Gap analyses of two ABS concrete technologies.
- Development of implementation requirements, testing programmes and approval pathways.
Initial deployment is focused on non-participating precast bridge abutment shells, providing a low-risk route for demonstrating these technologies in exposed durability conditions before progressing to load-bearing structural applications.
The project is being delivered in two phases: Phase 1 (November 2025 to March 2026) focused on desktop studies, standards development, gap analyses and small-scale testing; Phase 2 (June 2026 to March 2028) will undertake large-scale testing and validation to support wider implementation across the Strategic Road Network (SRN). This case study covers Phase 1 and will be updated following completion of Phase 2.
Focus areas / business challenge
We're focused on decarbonisation and accelerating getting new low-carbon approaches onto the network.
National Highways has committed to achieving its Net Zero 2040 targets by reducing construction and maintenance related carbon emissions. Steel reinforcement and Portland cement remain major contributors to embodied carbon within highway structures.
FRP reinforcement and ABS concretes are emerging as suitable alternatives; however, lack of industry standards, assurance routes and long-term performance data limits adoption of such low-carbon alternatives. This project seeks to bridge that gap and provide confidence for future implementation.
Objectives
Demonstrating clear routes to reducing whole life carbon by lowering embodied carbon in reinforced concrete and mitigating long term maintenance impacts using non corrosive reinforcement.
Accelerating the road trial and adoption process by developing generic design and material specification departures, informed by physical testing and emerging UK and international standards.
Accelerating market uptake by providing assured, repeatable pathways for deployment, sending a strong demand signal to the supply chain and improving commercial viability through shared evidence.
Balancing pace with whole life performance, ensuring that short term carbon benefits are realised without compromising long term durability, safety or whole life cost.
Reduce design costs, construction time, maintenance costs and construction health and safety risks.
Success criteria
FRP reinforcement
Generic departures from standard:
- Identify key evidence gaps for wider FRP applications, including creep, (long term deformation under sustained loading) and fatigue performance.
- Develop generic design and material departures to support FRP use in low-risk applications such as bridge abutment shells.
- Identify implementation barriers and actions required to support wider adoption.
FRP reinforced L-wall:
- Develop FRP reinforced L-wall design, including drawings, key design parameters and carbon assessments.
- Prepare manufacturing documentation and a testing strategy.
- Identify a suitable testing partner and develop a costed programme for large-scale trials.
Low carbon (ABS) concretes
- Complete a Flex 350 gap analysis using Earth Friendly Concrete (EFC) as a representative example, including a supporting test plan.
- Develop National Highways implementation requirements for Flex 350 concretes.
- Undertake small-scale material testing to generate performance data.
How the project supports National Highways KPIs
Being environmentally responsible: Supports decarbonisation by enabling the use of lower-carbon concretes and FRP reinforcement, reducing both construction and whole-life carbon emissions.
A well-maintained and resilient network: Improves asset durability through corrosion-resistant reinforcement, reducing deterioration and extending service life.
Achieving efficient delivery: Reduces construction time, on-site labour and maintenance requirements through durable materials and off-site manufactured components, delivering whole-life cost efficiencies.
Improving safety for all: Minimises on-site construction activities through prefabrication, reducing workforce exposure to construction risks and improving end-of-life material circularity.
The approach
The project adopted a collaborative approach involving National Highways, Laing O'Rourke and Ramboll. Existing research, prototype trials and previous industry investment were leveraged to accelerate learning and maximise value for money.
Activities undertaken during Phase 1 included:
- review of prevalent UK and international standards.
- development of generic FRP departures for design and material specification.
- assessment of ABS concretes against Flex 350 requirements.
- completion of gap analyses for two low-carbon concrete technologies.
- small-scale material testing.
- preparation of large-scale testing methodology for Phase 2.
- engagement with National Highways SES specialists.
- supply chain collaboration to understand implementation requirements and commercial barriers.
Using Laing O'Rourke’s existing manufacturing capability enabled the project team to generate meaningful evidence rapidly and cost-effectively while ensuring outcomes could be shared across the wider industry.
Project obstacles and how they were addressed
Intellectual property (IP): The use of proprietary products required bespoke contractual arrangements, which delayed contract award; this was resolved through collaborative development of IP clauses that are now informing Phase 2 and future innovation projects.
Compressed timescales: Delays in contract award shortened the Phase 1 programme, but this was mitigated through parallel working, regular and timely progress reviews and a one-team approach across project partners.
Carbon footprint verification: Limited availability of verified carbon data and Environmental Product Declarations (EPDs) created uncertainty in assessing carbon benefits; the project responded by defining the evidence requirements for implementation, incorporating further verification activities into Phase 2, and engaging with manufacturers to emphasise the need for independently verified carbon data.
Missing FRP parameters: Critical data such as fatigue, creep and long-term durability parameters were not available through existing certification routes; a gap analysis was undertaken to define testing and evidence requirements for future adoption.
Limited availability of accredited testing facilities: A shortage of United Kingdom Accreditation Service (UKAS) accredited laboratories for certain concrete tests (elastic modulus and Poisson’s ratio) were identified; testing was procured through suitable facilities where possible and the issue has been included within the Phase 2 scope.
Supply chain readiness: Wider adoption depends on supplier investment in testing, certification and manufacturing capability; early engagement with industry has been used to clarify requirements and provide a stronger demand signal for future deployment.
Outcomes and impact
Phase 1 successfully delivered several important outcomes.
Technical outputs
- Generic FRP departures for design and material specification progressed
- Flex 350 gap analyses for two ABS concretes completed
- Small-scale testing programme completed
- Large-scale testing designs and programme defined
- Key evidence gaps identified for future implementation
Carbon reduction potential
Preliminary estimates indicate substantial carbon savings could be realised through deployment of these technologies:
- Around 60% reduction per modular shell unit
- Approximately 30% reduction in substructures for a 35metre span bridge
- Around 5% reduction (100 tCO₂e) across the whole bridge
Whole-life benefits
The use of non-corrosive FRP reinforcement has the potential to:
- eliminate steel corrosion as a deterioration mechanism.
- reduce maintenance interventions.
- improve durability.
- deliver lifecycle cost savings estimated at approximately 20%.
At the end of Phase 2 we will have more certainty regarding these potential savings.
Industry impact
The project was shared through the Transport Research and Innovation Board (TRIB) Delivering Efficiency Through Technology Adoption programme, creating wider collaboration opportunities and facilitating knowledge exchange with organisations including HS2.
User and stakeholder outcomes
Designers
Generic departures provide clearer routes for design, specification, approval and implementation, and reducing risk / uncertainty.
Suppliers
Gap analyses provide guidance on evidence requirements, testing expectations and certification needs, enabling suppliers to plan future investments.
National Highways
The project strengthens National Highways' leadership position in infrastructure decarbonisation while providing practical pathways for introducing innovative materials safely and efficiently.
Wider industry
The outputs can support broader adoption across infrastructure sectors by creating reusable evidence, methodologies and assurance processes.
Key insights and learning
Phase 1 improved understanding of the technical, assurance and implementation requirements for FRP reinforcement and low carbon concretes, while identifying the evidence gaps that must be addressed to enable wider deployment across the SRN. The project also highlighted several practical considerations that will be critical to supporting safe, efficient and scalable adoption. Key lessons include:
- Lower-risk modular and non-participating components provide an effective route for trialling innovative materials before wider structural deployment.
- FRP reinforcement offers significant durability benefits but requires further validation of long-term performance and material properties.
- ABS concretes have strong embodied carbon reduction potential but require additional durability and performance validation.
- Combining FRP reinforcement with low carbon concretes offers significant benefits but requires further testing to demonstrate long-term performance.
- Clear departures from standards, proportionate testing and standardised specifications are essential to reducing adoption barriers and accelerating implementation.
Future value and next steps
Phase 2 will build on the foundations established by Phase 1 and focus on:
- large-scale structural testing
- durability validation
- assessment of combined FRP and ABS performance
- development of expanded departures and guidance
- validation of specification and approval pathways
- investigation of practical deployment opportunities on the SRN
The programme will also seek to address key barriers identified in Phase 1, including:
- long-term performance evidence
- supply chain scalability
- testing capability
- carbon footprint verification requirements
- practical design methodologies
- inspection and maintenance requirements
The long-term aspiration is to provide National Highways with validated design, specification and assurance pathways that support widespread implementation of lower-carbon and more durable structural solutions while contributing to net zero objectives.
