This resurfacing project was a demonstration trial in the use of ‘in situ’ recycled of road material with the additional introduction of graphene to strengthen and prolong the working life of the road surface. We worked in collaboration with Stabilised Pavements Ltd to remove, recycle and re-lay the existing road surface using new ‘in-situ’ Cement Bound Granular Material (CBGM) recycling technology and equipment without the material leaving the site. DSD Construction were responsible for the planing out and reinstallation of the road surface material in close collaboration with Stabilised Pavements Ltd which required close collaboration and coordination of plant and personnel with a continual production line of over 100 metres of plant and equipment.
To lay the recycled material, we deployed our new Volvo tracked paving machine which allowed us to lay the full depth of surfacing material directly onto the sub surface in one pass to a tolerance of +- 6mm. This removed the requirement to lay a binder course, significantly reducing cost and schedule and reducing the carbon footprint of the project. Additionally, the Volvo paving machine uses new compaction technology to compact the asphalt as it is laid, achieving 70% of its final compaction value – reducing the amount of subsequent rolling required. To reduce the amount of rolling further, we employed a Pneumatic Tyre Roller which uses a kneading action to efficiently compact the asphalt in fewer passes.
The trial also involved the use of raw graphene mixed with the CBGM over 30 metres of the road resurfacing to form a new stronger recycled road surface. After several months of lab-based development at the Graphene Engineering Innovation Centre (GEIC) at The University of Manchester, this project was used to test in-situ recycling of road surface with added graphene as a ‘world’s first’ trial in collaboration with Pavement Testing Services (PTS).
This was a trial in the use of new materials (CBGM and graphene) using new equipment. To ensure the trial was successful at site, we carried out a series of practice operations at our Carlisle HQ prior to the project.
The reuse of surfacing material without leaving the site and the use of new paving equipment has significantly shortened the project schedule, reduced the carbon footprint of the project and reduced the amount of disruption to road users. Additionally, the trial of graphene in road surface material has the potential to extend the life of the road surface – further reducing lifetime cost, disruption to road uses and the lifetime carbon footprint of the road.
Graphene’s benefits are industry-changing. It is stronger than steel and adding it to other materials can turn them into super materials. From what we’ve seen so far, it could make some of our assets last significantly longer.
Asset Needs Manager, National Highways