Road reinforcement mesh from geotechnical specialists Maccaferri, has proved its value by continuing to perform as intended, after nine years of intensive trafficking on the busy A75 trunk road in Scotland.
The A75 in Dumfries & Galloway, links the A74/M74 at Gretna with the west coast port of Stranraer, carrying thousands of heavy goods vehicles, day in day out.
Much of the road had been the subject of improvement during the late 1980s but problems of settlement had persisted. On one particular section to the east of Newton Stewart, a new section of road was constructed over poorly drained clay sub-grade and the constant heavy traffic loading had caused severe deflection of the wearing course.
Following unsuccessful attempts at remedial work and a period of visual monitoring, engineers at Dumfries & Galloway Combined Services Department approached Maccaferri for their expertise in asphalt pavement reinforcement systems.
Both sides of the single carriageway road required attention and it was decided that a 1,000m long section of road be reconstructed using Maccaferri’s Roadmesh, double-twist wire, reinforcing mesh as part of bituminous asphalt overlay.
Roadmesh is intended for installation within the bituminous layers of the pavement. In remedial overlays the old wearing course is usually planed off and the Roadmesh placed on the exposed surface, then overlayed with a new base course plus wearing course. Roadmesh causes the overlay to work as a cohesive mass, absorbing the horizontal tensile stresses and spreading the imposed traffic loadings over a wider footprint, thus reducing its damaging effect.
On the A75 project, the reinforcement system was installed by Dumfries & Galloway [D&G] Council with Barr as the main Contractor. Since its installation in 1999, the road surface has performed as intended with no repeat of the wearing course damage, previously experienced.
Commenting on the A75 Roadmesh project, Dave McRoberts, Principle Roads Services Officer for D&G Council, Wigton, and the engineer in charge of the installation at the time said: “A reinforced overlay was the only practical solution bearing in mind the poor ground conditions and high water table in the area. Excavation and importation of stone for a traditional reconstruction would have been uneconomic and too disruptive on such a busy trunk road.”
Maccaferri Roadmesh provides high tensile strength at low strain and, together with its unique 3D geometry, creates excellent aggregate interlock to optimise load transfer and shear resistance. The system was initially developed to inhibit reflective cracking in asphalt layers and research has shown that the incorporation of Roadmesh can enhance the working life of the whole pavement.
The system has been used widely in Europe and has been shown to increase the duration of pavement maintenance lifecycles.