AASHTO Journal, 16 September 2016
The Wisconsin Department of Transportation calculated that it saved nearly $1.5 million this year from four pavement projects that used an innovative “cold-in-place recycling” to replace road surfaces. WisDOT has been making annual evaluations of field data from cold-in-place recycling projects. Based on results gained so far, cold-in-place recycling has shown better performance against cracking compared to the mill and overlay sections.
WisDOT said the recycling projects showed average cost reductions of 17 percent per mile, compared with traditional paving methods.
It explained that with cold-in-place recycling, machinery mills the existing asphalt road surface and processes that material for on-site reuse, as a convoy of equipment crushes, adds new liquid asphalt and paves simultaneously.
The department resurfaced 28.47 centerline miles of road using that method this year, for an estimated on-site reuse of 93,450 tons of material or enough to fill more than 4,600 quad-axle dump trucks.
“With cold-in-place recycling, we’re reducing the cost to taxpayers while also cutting down on project time and the associated delays for drivers,” said Barry Paye, engineering chief in the materials management section of WisDOT’s Bureau of Technical Services.
He said that had WisDOT not reused the old pavement, removing that material would have generated enough loads “to stretch a line of dump trucks more than 22 miles. That’s important, because as those trucks stay parked, we save on fuel and create less wear and tear for our highways.”
As with any technique, WisDOT said, cold-in-place recycling works best under optimal conditions, on roads where the pavement surface is worn and cracked but the subgrade below is still firm and in good shape.
WisDOT has used the technique in seven different road projects statewide since 2012, and continued monitoring so far has shown favorable results compared to traditional resurfacing methods.
It said it has conducted annual evaluations of field data from the projects. Where it used cold-in-place recycling, WisDOT said the benefits included reducing pavement project time, which also reduces delays and inconvenience to road users.
It of course curbed the need to haul materials, significantly cut trucking costs and the need to buy new materials. So it had a lower initial cost than traditional repaving.
The department also said the recycling method generally results in lower maintenance needs as well, and the pavement has more durability and less cracking.