Red Dog Zinc Mine
Knik Construction Inc invited Wirtgen and Loudon International, to assist with the development of a specification, work plan and trial section for the rehabilitation of the haul road at the Tech Cominco Red Dog Zinc Mine. Due to the remote location of the mine, the rehabilitation process was to recycle the existing pavement and stabilize with foamed bitumen.
The Red Dog Zinc Mine is some 50 miles from the nearest port from where the zinc is distributed throughout the world. The haul road between the mine and the port was constructed from gravel material and is showing signs of deterioration due to severe heavy haul trucks using this road on a daily basis.
The original road was constructed with nominal aggregate size ranging from 60mm to 10mm in various layers with various thicknesses. The top layer however consisted of 250mm crushed gravel base, but due to constant hammering from the severe heavy loads the top 50mm to 100mm were raveled and deposited on the side of the road.
For the mix design 125mm of imported crushed stone was proposed before the top 250mm layer was stabilized using foamed bitumen. No cement was added due to unavailability in the remote area. The high fines content of the in-situ material assisted with the dispersion of the foam bitumen and therefore the addition of cement was not a necessity for this project.
A trial section of 1km was stabilized and sealed using a single surfacing seal. After a heavy rainy season, four months after construction completion, the trial section was still intact, while other sections of the road experienced severe deterioration in the form of potholes.