Better Roads Staff
The result, says Gallagher, is a finished pavement that needs no surface treatment, can be opened to traffic in short order, and has a projected service life of a decade or more, assuming the original pavement was adequate for the current and future traffic loads.
Based in south-suburban Chicago, Gallagher Asphalt is one of the largest asphalt producers in Illinois, and one of the leaders in heat scarification HIR, both in its home state and nationally. The Re-HEAT system will add to the diversity of solutions the company offers, says Patrick Faster, national sales director of the company’s hot-in-place recycling operations.
“Compared to a conventional mill and fill, it saves a lot of time and a lot of money. It also costs less than heater-scarification HIR and an overlay,” says Faster.
Dan Gallagher, who owns and operates Gallagher Asphalt with brother Patrick and cousin Charlie, notes that there are applications where heater-scarification HIR is the better fit. “If the existing pavement structure needs to be stronger, the overlay of virgin mix that comes with heater scarification is the better option,” he points out.
Chicago Department of Transportation officials watching the demonstration project were enthusiastic about the concept and interested to see the results. Along with the potential cost savings, Gallagher Asphalt quotes a study that indicates Re-HEAT has a 63-percent smaller carbon footprint than a conventional 2-inch mill-and-fill and fill using 20 percent RAP in the mix — the benefits of eliminating virgin materials and delivery trucks.
As the first outing for Gallagher’s Re-HEAT equipment, the Chicago demonstration project made good on much of the system’s promise while also showing its main challenge. On the impressive side of the ledger, operating in cool weather and on a pavement that may have been older than many of the onlookers, the new recycling train produced smooth, tight asphalt to a depth of 1.5 to 1.75 inches. Densities were reading in the 93- to 94-percent range and the recycled surface was opened to traffic a short time after the HIR train passed.
On the “challenge” side of the ledger, there were several instances when the recycling machinery hit segments of oil-rich road patches and produced thick clouds of smoke and fumes, reminiscent of the early days of HIR applications several decades ago. This is not likely to be a persistent problem with the Re-HEAT system, the Gallaghers say, pointing out that the Re-HEAT heating technology is identical to time-proven heater-scarification equipment. The smoke on this demonstration project resulted from an unusual degree of variation in the surface asphalt content, the cool weather conditions, and a crew just getting familiar with new equipment.
Perhaps the ultimate view of the project came from several residents on the street, who turned out to thank the crew, the DOT officials and their alderman for the miracle being performed on their street. Few would have lived there long enough to remember when the road last had a smooth, new surface.