Efficiency is a key driver in Highways England’s Roads Programme and making use of innovative technologies is essential. During the Surtees Bridge resurfacing, Tarmac and A-one+ worked in partnership to cut costs, carbon and project timescales, while minimising disruption for users of this busy stretch of the A66.
Ian Carr, technical manager at Tarmac, explains:
“As part of our early engagement, we explored the use of Tarmac’s Ultilow solution. Low temperature asphalt technology has contributed to reducing resurfacing timescales and cutting carbon on many projects and we felt that there was a real opportunity here to minimise disruption.”
Tarmac Ultilow is mixed at circa 40°C lower than the 170°C to 190°C of regular hot asphalt. These lower temperatures are achieved by modifying the behaviour of the bitumen either through foaming or using a warm mix additive during manufacturing.
Bitumen foaming involves injecting a small quantity of water into hot bitumen, which steams and produces bubbles. This increases the volume of the bitumen, temporarily reducing its viscosity and making it easier to fully coat the aggregate.
Warm mix additives reduce the surface tension of the bitumen, allowing the mix to be manufactured and compacted at lower temperatures.
The quicker-cooling asphalt enabled faster completion on the Surtees Bridge project, increasing the productivity of the workforce and allowing the road to be re-opened sooner. Tarmac planed and refurbished the 19,745-metre area in one month.
Compared with similar schemes, the use of low temperature asphalt on the A66 helped to reduce the project by 14 shifts, equating to savings of £67,000.
Low temperature asphalt can also deliver carbon savings of up to 25 per cent. In this instance, around 14 tonnes (14.2 tCO2e) of carbon were saved compared to a project using traditional materials.