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For this project Coughlin added 2.5 percent PASS emulsion supplied by Western Emulsions; and 1.5 percent lime slurry (by weight) was injected as well. The slurry was approximately 35 percent solids to water by weight and prepared by a nearby slaking plant.

Calibration routines for the Roadtec RT-500 cold recycler were worked out by Roadtec to achieve correct proportions of liquids and solids per specification. A BearCat brand 1,000 gallon liquid calibration trailer was used to help with the calibration of the RT-500's emulsion pump.

After an approximate two-week curing period, Frehner Construction placed a 3-in. hot-mix overlay on top of the 3-in CIR base.

The cost-effective benefits of CIR are clear, according to Coughlin. First, the process saves time. With a single train of equipment, the reconstruction is done in several hours versus several days. Secondly, the process generates substantial savings in the cost of raw materials, manpower and energy. And finally, the recycling process extends the service life of roads, which is important to road agencies and taxpayers.

Environmentally friendly

The CIR process preserves natural resources by reusing 100 percent of the old HMA layer. This also alleviates trips to a landfill, thereby reducing transportation costs and fuel emissions. With a train of equipment moving in sync to reconstruct the roadway, the overall emissions are reduced due to decreased trips to and from the construction zone.