Even though this was a new experience for the county, engineers there did not feel that they were going out on a limb with foamed asphalt. "We're looking to save money with new technology, and if this works out we will try it on other roads," Adamczyk says. "We just want to see what kind of problems we may run into, and what to expect in the future. The contractor has the process down, they know what they are doing. I was surprised to see just how little oil you actually see after the pulverizer goes through, but it's there when you test it. It looks very stable, and feels very stable."
Dunn Co., the contractor, is attempting to interest Illinois counties in new technologies in reclamation, whether foamed asphalt or asphalt emulsion. As Dunn's WR 2500 S can do either form of stabilization, the firm tries to determine which is more appropriate for the customer.
"We're trying to get the counties to think about either foam or emulsion reclamation," says Jim Schwarz, vice president, Dunn Co. "All roads are different; some are better candidates for the emulsion, some are better for foam. Some are neither; fly ash or cement stabilization may be better."
Cores taken of County Road 9 were analyzed by Dunn Co., which determined that the road was a better foam candidate. "With this application, we knew we had the stability we needed with the materials here. We were looking for some minus 200 material that still had some pozzolanic action, so we went with Class C fly ash," Schwarz says.
Using a Wirtgen W 2200, Dunn also undertook the cold milling of asphalt on the western section of the project, and distributed the 4 inches of millings on the foamed section.
Dunn is getting a strong interest from the counties as it undertakes foamed projects. "The response has been very good," Schwarz says. "With every job we do, we get a lot of people who want to come and watch what is going on, and see the results when it's done."
Supporting this outreach to the counties is the WR 2500 S. "The capabilities that it gives with the one-pass mixing, and the way the mandrel [drum] mixes, is by far the best machine for mixing oil like this," Schwarz says. "It's a very reliable machine."
Including the WR 2500 S, Dunn has seven Wirtgen machines: a W 2200, two W 2000s, two W 1900s, a W 1000, and a W 600.
Later in the summer, Dunn Co. used a Wirtgen 2200 CR, which offers contractors and road agencies the best of both worlds, in that it's a cold in-place recycler — and conventional cold milling machine — in one robust unit.
This cold recycler processes roads with an integrated paving unit, but also serves as a high-performance cold milling machine which can remove asphalt courses to a depth of nearly 14 inches.
Offering performance well beyond conventional cold milling machines, the 2200 CR permits mixing of water-cement slurry, asphalt emulsion or foamed asphalt road base to a depth of 6 inches, all the while being capable of cold milling as desired. The machine has a cutting width of 87 inches, with an hydraulic, all-crawler travel drive. Its operating weight is 101,851 lbs. and boasts an 865 hp power plant.
In the meantime, Adamczyk and the county engineering department will be studying the performance of County Road 9. "We will be watching this road," Adamczyk says. "We will want to see how it behaves through different seasons, under different conditions, such as snow plows. But so far, I like it. It's very impressive."