A key strategic road in Norfolk has been given a new lease of life thanks to the installation of Tarmac’s largest ever supply of a specialist asphalt solution, specifically designed to maintain roads where the underlying concrete has deteriorated.
With the lean concrete base of an eight-kilometre section on both carriageways of the A11 near Thetford having been identified as in urgent need of repair, the company was tasked with finding a long-lasting and sustainable surface that would cut lifecycle maintenance costs.
Working in partnership with Highways England and project consultants Atkins and following a detailed whole-life cost analysis, Tarmac proposed the use of its fully recyclable ULTILAYER SAMI asphalt – a high-performance stress absorbing membrane interlayer, proven to provide long-term protection of the asphalt overlay.
Completed in July, the site team laid a total of 80,000 tonnes of material to complete the scheme including 7,000 tonnes of ULTILAYER SAMI – the most Tarmac has ever supplied to a single project. It has been estimated that, in addition to being fully recyclable, the asphalt will increase the life of the pavement, resulting in lower maintenance requirements, highlighting the substantial sustainability benefits of this product.
Phil Greenin, contracting framework delivery manager at Tarmac, said: “ULTILAYER SAMI is a proven technology that has been uniquely developed to tackle deteriorating concrete roads. Its previous applications on the strategic network, including on the M25, have demonstrated that its greater whole-life performance can extend pavement life, deliver longer resurfacing intervals and lower maintenance requirements.
“At a time when the highways industry is increasingly looking towards more sustainable and better value solutions, it has been really positive for us to not only supply but lay a record amount of this material on the A11. We know it will help to eliminate future interventions, together with the related carbon emissions and disruption associated with maintenance work.”
Asphalts used to traditionally overlay concrete often suffer from reflective cracking caused by thermal expansion in the underlying concrete and the effects of traffic loading, eventually leading to water ingress and failure that requires costly remedial work and can cause delays for road users.
Designed to be laid directly onto concrete, the material is a finely-graded asphalt containing a heavily polymer modified binder (PMB), which provides a durable buffer to accommodate movement and prevent cracks appearing in the asphalt layers above. This was overlaid with a polymer modified binder course and surface course material to further increase the crack resistance of the carriageway.
Martin Fellows, Highways England’s regional director, said: “The A11 is a vital route providing thousands of drivers with a reliable route for work journeys and home deliveries, visits to friends and family, holidays and the movement of the goods and services. By using a product that is longer lasting and fully recyclable we’re able to extend the life of the road, reduce the amount of time undertaking maintenance and repairs, which minimises disruption to drivers, businesses and the local community.”
Tony Nicholls, transportation general manager at Atkins, said: "The work on this project has been a fantastic example of collaboration between Atkins, Tarmac and Highways England to find a treatment solution that has enhanced durability to delay the onset of defects and to minimise future maintenance interventions on the A11. Together we have eliminated the number of future maintenance interventions whilst also reducing carbon and improving efficiency benefits."
In addition to the new surface’s improved sustainability credentials, the Tarmac project team is ensuring that 100% of the old surface material will be recycled and is implementing a ‘carbon calculator’ to accurately identify where other emissions savings have been achieved.