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The pavement was placed in four lifts, with the three 3-inch base/binder courses consisting of a PG 64-28 AC, ½-in. aggregate dense mix with lime additive to prevent stripping. The top 2-inch wearing course was produced with a PG 70-28 AC binder, ½-inch aggregate and lime additive.

"The contract called for a rich mix design (6.5 percent) and an anti-stripping agent (lime)," Seehawer says. "We were also allowed to use up to 30 percent RAP (reclaimed asphalt pavement) in the mixes we produced and placed; but since we were constructing a new road, we didn't have a RAP resource and had to go with all virgin materials."

Echelon paving
Since the U.S. 97 project was a new road, the contractor's crews had the luxury of working without the traffic challenges normally associated with a typical mill and fill project.

"We had as many as four different pavers (Blaw-Knox) on the project at any given time, allowing us to pave in echelon," Seehawer says. "Paving in echelon not only allowed us to increase production, but also allowed us to achieve better longitudinal joints, especially between the two mainline travel lanes and do so using only three or four (IR) double-drum vibratory rollers."

Without traffic concerns, paving crews were also able to extend screeds to hot-lap turning lanes and other expanded areas, which eliminated longitudinal joints in the process. Along with the two 12-foot-wide travel lanes in each direction, the paving crews also constructed a 10-foot-wide outside shoulder and a 7-foot-wide inside shoulder along the concrete barrier.