10 June 2020
sponsored by RIFT R&D
The construction industry relies on aggregate for survival but pressures are mounting for it to change with the climate crisis and environment impacts. In their 60 years of operation, FM Conway has pioneered aggregate recycling and has committed to delivering innovation in this area, becoming fully self-sufficient by producing high-quality materials or virgin counterparts. They have now delivered an innovative new process utilising Recycled Asphalt Pavement (RAP) that could change our roads and they believe this approach should be adopted across the UK.
In September 2019, FM Conway helped lay an asphalt surface course containing 50% recycled content on the M25, between junctions 25 and 26. Highways standards usually dictate that UK motorway surface courses must only contain a maximum of 10% recycled materials. However, FM Conway has worked closely with Highways England and their delivery partners to create a specially designed mix for use on the M25. The bespoke surface course contained 50% high polished stone value (PSV) recycled aggregate (RA). As the project featured on one of the UK’s busiest and most important roads, the surface required stone with a high PSV as an important measure of the skid resistance of the surface.
The new surface course was created by mixing RAP with virgin aggregate and FM Conway’s own designed and manufactured polymer modified bitumen (PMB). The PMB was added to significantly improve the durability of the surface course by improving resistance to rutting and cracking.
The RAP came from two donor sites within the Connect Plus area, and the planings from the two sites were taken to FM Conway’s Colthrop recycling plant, where they were crushed, screened, tested, segregated and stored. The day before the material was due to be laid, the planings were transported to the company’s Heathrow recycling and asphalt plant for mixing with the virgin aggregate and PMB.
The project has proven to be groundbreaking in showing that higher percentages of RAP content should be used on the strategic road network (SRN) to achieve more environmental benefits within their work in the industry. Aggregate and bitumen are finite resources, whereas planings are readily available as a by-product of road improvements and the industry should consider using them to reduce both carbon emissions and transport movements.
The use of 50% recycled content marks a step-change in the use of recycled material on UK roads that could result in huge environmental benefits if adopted across the network. Road maintenance sits at the heart of the construction industry and by working with large clients such as Highways England, they have helped to deliver a more sustainable method that should be considered as a solution to the current climate emergency.
About the Innovation Award:
Innovation is widely recognised as the critical factor for increased and sustained productivity and growth. It demonstrates an organisation’s confidence, capacity and appetite for improved performance and productivity gains. Innovation is most effective as a holistic approach that identifies both demand and ideas and is most successful when supported by collaboration between customers and the supply chain.