Roadway Recycling Cuts Costs, Spares Environment

Having reached its expected 20-year design life, a 1.8-km section of the Aviemore Bypass between Perth and Inverness (Scotland) had developed 3-mm-wide transverse cracks in the lean-mix base at approximately 20-m intervals. The cracks had migrated to the surface allowing rain water and road salts to enter and degrade the lean mix beneath.

Acting on behalf of the Secretary of State for Scotland, the North West Partnership awarded Colas Limited a contract to carry our repair work using its In-Depth Road Recycling. The technique involves planing and pulverizing the existing road material to a depth of 375mm. The levels are reduced and 100 pen bitumen binder is introduced in a 240mm layer to produce a bitumen-bound recycled layer with a stiffness of 2500 MPa.

Colas's In-Depth Road Recycling takes about half the time of conventional road maintenance techniques, at considerable cost savings. Approximately 1000 m2/day of recycled road surface can be treated and laid. Such rapid progress minimizes disruption to traffic and conserves natural resources, resulting in an estimated energy saving of up to 95%.

Brian Hicks of Colas Limited late in 1998 delivered a modern road-recycling presentation to 60 Scottish highway engineers representing local authorities from as far north as Sutherland and as far south as Edinburgh. The presentation included a site visit to the road-recycling project taking place on the A9 Aviemore Bypass.

Brian Guthrie of the Scottish Office Network Management Division has said, "The Scottish Office's National Roads Directorate is committed to utilizing road recycling methods wherever possible. We anticipate a steady increase in the use of road recycling techniques as more knowledge is gained. It is now normal practice to consider road recycling for all major road repairs because of the environmental cost and time benefits. The recent GBP 400,000 recycling contract on the A9 Aviemore bypass attracted considerable attention from engineers all over Scotland. The ongoing technical appraisal of the project will further help to increase awareness of the benefits amongst engineers."

Contact: Crow Communications, Andrew Fitchett. Tel: +44 (0) 1273 737398; Fax: +44 (0) 1273 737358. Colas Limited, Vicky Armstrong. Tel: +44 (0) 1342 711000; Fax: +44 (0) 1342 711199