Low temperature asphalt
The sustainability benefits of warm rather than hot asphalt are well known - energy saving, lower emissions and enhanced durability. Now the product’s ability to get traffic flowing again quicker have been demonstrated on a project on the A66 in Cumbria.
Hanson’s contracting gangs had to start at 7.30pm, plane out and replace around 350 tonnes each night and have the traffic running again by 8am the next morning. It required materials that could be compacted well despite the low temperatures and which would harden rapidly.
After examining various options, the technical team proposed lower temperature mixes for the base and binder courses using a highly modified 40/60 pen binder developed in collaboration with Nynas. The client Kier, contractor to Highways England, agreed to the low temperature solutions and the Hanson team laid two layers of base course, a binder course and a Tuffgrip thin surfacing between 10pm and the morning cut off point.
The binder ensured lower temperature compaction and rapid hardening of the asphalt, which in turn allowed for two to three layers to be laid each night, despite the cold. And it could be trafficked rapidly without the deformation which could happen if a conventional 50 pen bitumen had been used.”