The material was installed for work on the A26 Beddingham and A259 Winchelsea. By positioning it as a like-for-like replacement under Clause 948 of the Specification for Highways Works, rather than as an experimental material, Roadways was able to avoid a lengthy programme of trials. This, the company says, is a first for the strategic road network managed by National Highways, and promises to speed adoption of low carbon replacement materials.
The cold binder is produced using 100% recycled aggregate, eliminating virgin materials in the layer where it was used. Roadways acted as principal contractor, material producer and installer on the project, manufacturing the material using cold bitumen emulsion at its recycling facility in East Sussex. Planings removed from the roads during the project were returned to the facility, to be recycled.
The project was made possible by early engagement. Roadways raised a design query, which led to the collaboration needed with National Highways and the scheme's designers. As part of the process, Roadways demonstrated that the material could be deployed as a direct replacement for AC20 binder, within existing specifications.
Carbon savings were made as a result of removing the need for high temperature manufacture and installation, and through the 'back haul' approach taken to delivery of new asphalt and removal of planings.
Around 1,300t of material were delivered. This resulted in an estimated saving of 23-25t of CO2. By using back haulage, and eliminating empty return journeys, a further 2.4t of CO2 emissions were saved.