A small revolution is taking place in road surfacing and maintenance.
International trade in road surfacing and maintenance ideas has been around for some years, but has started to intensify of late, says managing director of UK roads contractor Ringway, David Lee.
Using a technique developed by Ringway's French parent company, Eurovia, the firm is blazing a path for the reuse of road planings. Thousands of tons of materials are disposed of to landfill sites in the UK every year, but recoating them with foamed bitumen makes them suitable for use as fill and as structural base layers.
Foamed bitumen is created by mixing water plus foaming agent to hot bitumen, which evaporates the water, triggering the foaming process. This is added to cold aggregate. The material can then be stockpiled and stored for several months.
Advantages of the system are firstly cost savings on haulage and disposal of planed or excavated materials. Because the aggregate in planings already contains bitumen, relatively little additional foamed bitumen is needed to bind them when relaid.
And the cost of high grade virgin materials in the UK is soaring. High PSV aggregate is now being imported from Ireland, Scotland and further afield. 'High PSV materials are a finite resource, ' says Lee, and should not be squandered by using it in base layers. It should be used only where its value can be best realised - that is, in providing skid resistance in the wearing course and dressing.
Designing with recycled materials requires constant checks on quality and strength, as both vary from batch to batch, says Eurovia director Maunel Dufat. But the company now has extensive knowledge and experience in reclaiming materials, so design adjustments can be made fairly easily to construction depth or by adding virgin materials to gain required strength and performance.
No cost comparisons between primary and recycled materials have been carried out in the UK yet, but savings are significant says Lee. On a framework contract for Lincolnshire County Council, Ringway is now recycling close to 80% of all the material it removes.
Eurovia is keen to push the technology north into the large but relatively 'conservative' road maintenance markets of Germany and Scandinavia.