For more than a quarter century, Tinley Park has retained the services of Robinson Engineering to handle its engineering needs for transportation and other infrastructure categories, and to assist in managing projects. Robinson Engineering sold the village on the concept of rehabilitating pavement long before it deteriorates into the critical zone.

As a result of this strategy, Robinson and Tinley Park became one of the pioneer users of hot-in-place recycling back in the 1980s. Always on the lookout for ＆#118alue-added ideas and processes, Robinson began specifying HIR for Tinley Park and its other clients more than 30 years ago.

The initial projects were successful and hot-in-place recycling has been one of the mainstays of Tinley Park’s prevention program ever since.

Christopher King, P.E., president of Robinson Engineering, says hot-in-place recycling typically saves the agency more than 30% compared to a standard mill-and-fill operation (milling off the top 2 inches of old asphalt and replacing it with new hot mix). And equally important, the HIR process can be done in about half the time, says King.

The process

For the past 20 years, most of Tinley Park’s HIR work has been performed by Gallagher Asphalt, an 80-year-old, family-owned asphalt producer/contractor with multiple plant locations in the Chicago area.

The hot-in-place recycling process used by Gallagher and Tinley Park is a multi-step, continuous method that heats the pavement slowly to a viscous state, introduces a liquid rejuvenating agent, then remixes the pavement with tines and augers, usually to a 2-inch depth, which removes typical aging imperfections.

The heated pavement is then re-profiled and compacted. The rehabilitated pavement then receives an overlay of fresh hot-mix asphalt — usually a 1.5-inch lift. For some applications, less expensive surface treatments are used, including micro surfacing, chip seals, and slurry seals.

Robinson, which has contracts with 36 municipalities in the region, says the savings HIR offers are even higher today, with liquid asphalt prices having more than doubled in the past year or so.

Gallagher Asphalt

Gallagher Asphalt’s HIR division is currently under contract to complete about 175,000 square yards of recycling for Tinley Park this year. The work is spread over a number of different streets and locations. Most of the work will recycle the top 1.5 to 2 inches of pavement. A 1.5-inch overlay of new hot-mix asphalt is being laid by the primary contractor.

Depending on the locations and pavement composition, Gallagher recycles in excess of 10,000 square yards per day.

Gallagher has had a close relationship with the village and with Robinson Engineering for many years, partly because they are located in close proximity to each other, and especially because as Patrick Faster, head of the company’s HIR division, says, "They spec a lot of hot-in-place and we do it."

Faster points out that Gallagher’s HIR customer base has been comprised of forward thinkers. "We’ve been doing this for 20 years, so a lot of our long-time customers are way ahead of the curve," he says. "Many of our agency people and consulting engineers signed on to HIR years ago, realizing that aggregates and oils are in inelastic supply. Today, with agencies seeing 50% to 100% increases in installed tonnage prices (for new asphalt), even more of them are becoming forward thinkers."

Even without the price spike in liquid asphalt, HIR makes imminent sense for a pavement management program, Faster points out. "If you have two towns the same size, one using HIR, the other not, the non-believer may be doing 10 miles of standard rehab a year while the recycler is doing 13 miles," says Faster. "At the end of five years, the recycling program has rehabbed 15 more lane miles than the other town...and that’s how you get big OCI numbers."

Finding contractors

For agencies interested in starting in-place recycling programs, Faster says a good place to look is the Asphalt Recycling and Reclaiming Association Web site. It lists dozens of contractors and what specialties they perform — hot-in-place, cold-in-place, full-depth reclamation, soil stabilization, and milling.

Many of these contractors are very mobile. Gallagher, for example, focuses on the upper midwest during the spring and summer, then moves its HIR trains south in the winter. Many other recycling contractors have a similar seasonal migration.

There is another benefit to locating a recycling contractor through ARRA, says Faster: not only does the organization focus exclusively on recycling, its member contractors are dedicated to the processes and have literally written the books on cutting edge techniques and technologies.