GALLAGHER PAVES OHIO HOT IN-PLACE BY SARAH REDOHL
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Gallagher’s custom-built hot in-place recycling equipment includes two preheaters and a process machine. Hot in-place recycling (HIR) is a pavement preservation treatment where an asphalt pavement is heated and remixed on-site and inplace reusing 100 percent of the existing materials. According to the Pavement Preservation and Recycling Alliance (PPRA), HIR reduces greenhouse gases by up to 30 percent and costs anywhere from 20 to 40 percent less than conventional rehabilitation techniques while offering same-day return to traffic and extending pavement life by seven to 15 years. And, the treatment option is growing in popularity. “It seems to us we are doing more and more HIR with each passing year,” said Patrick Faster, national sales director at Gallagher Asphalt Corporation, Thornton, Illinois. Today, the company has six sets of HIR equipment and dedicated HIR crews performing jobs in more than 20 states around the country. Faster thinks demand is increasing both as a result of the increasing cost of asphalt and increasing interest in sustainability. He compares HIR to cold in-place recycling (CIR) and full-depth reclamation (FDR), the common denominator being the use of existing material in place to minimize hauling and use of virgin materials. “HIR fits the niche in a roadway’s life cycle where it doesn’t quite need CIR or FDR,” Faster said. That was exactly the case on two recent projects Gallagher performed for Delaware County, Ohio, where HIR was used to level out the roads and improve rideability at a reduced cost compared to a mill and overlay.
38 / November 2021
HIR is often an attractive option for roads without significant depth, “where the last thing you want to do is mill anything out,” Faster said. “Instead of milling and hauling off a couple inches and then paving on a couple inches, you can use HIR on the existing pavement and then add a couple inches of new asphalt on top of it. Then, it’s a net gain in terms of strength while also reducing tonnage.” HIR can also appeal to parts of the country where aggregate is particularly expensive, as well as for agencies who rely heavily on chip seal. “Many agencies use chip seals on lower volume roads, but there comes a point where chip seal won’t cut it anymore,” Faster said. “That’s where HIR can go in first, and then the agency can go back to chip sealing the road.” Faster said HIR is ideal for roads with poor ride quality, heavy rutting and surface degradation. However, Gallagher is particular about the roads on which it performs the process. They take cores of prospective roads and simulate the HIR method in the lab to see if the treatment works well on that prospective road. “The lab results dictate whether or not that road will be a good candidate for HIR,” Faster said. Gallagher doesn’t perform HIR on pavements with drainage issues and requires that the road be structurally sound, since HIR itself doesn’t enhance a road’s structure. “We’re only working the top 1.5 inches or so,” Faster said. “If you have a deeper problem, you’ll need to look at another treatment method.”
