A77 Stranraer – Beach Cottage Ex-Situ Recycling Scheme 

Amey proactively engages with our supply chains when carrying out road maintenance to minimise the use of carbon in materials and reduce waste. In September 2022, an ex-situ pavement recycling scheme was completed on 1,061m of the A77 between Stranraer and Beach Cottage.  

Ex-situ recycling involves the removal of old planings off-site to a nearby quarry, where they are reprocessed and encapsulated with other materials before being brought back to site and re-used as the base layer of the road surface. The reprocessing of planings via ex-situ recycling is much less energy intensive than the manufacture of virgin materials. 

A total of 2,060 tons of hazardous tar-bound and not tar-bound materials from four sites were stabilised with bitumen emulsion, cement, and pulverised fuel ash, before being used as base and binder courses on the A77 site. Traditionally, hazardous tar-bound materials would have been sent to specialist landfill sites to be disposed of there. The ex-situ recycling process has therefore avoided the use of landfill as well the need for virgin materials. It also reduces the number of lorry journeys that would be needed to transport the coal tar planings to specialist landfill sites, the nearest of which is in England. 

Our calculations have shown that sending tar-bound materials to landfill and choosing instead to use virgin materials would have resulted in emissions of 122 tCO2e, while the ex-situ recycling scheme resulted in emissions of just 44 tCO2e. This process saved a total of 78 tCO2e. 

In future projects, it is possible that even further savings could be made from changing to electric HGVs and from incorporating in-situ recycling to reduce transport emissions. In instances where ex-situ recycling is not possible, there will be opportunities to use recovered waste materials such as glass in place of virgin aggregates to reduce the material demands of the project. This is the second ex-situ recycling scheme to be undertaken on Scotland’s South-West Trunk Roads since the network maintenance contract commenced in 2020, with the first completed on the A76.  

Click the diagram below to enlarge: