Better Roads

December 2014

Better Roads Digital Magazine

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Better Roads December 2014 31 crete underlayment. For their contractor to mill the on-aver- age 4.5-inch depth, Norris Asphalt had to close the stretch to traffi c for 17 days. "The rest of the highway project was milled cold-in-place with traffi c fl ow maintained throughout construction," says Bob Mobley, paving superintendent with Norris Asphalt Pav- ing Co. "The milled asphalt was recycled – we used 20-per- cent RAP in our HMA [hot-mix asphalt] mix." For the highway project, Norris Asphalt laid 12,230 tons of HMA for the base lift and 24,840 tons of asphalt was placed for the intermediate and surface layers. An additional 7,500 tons of HMA was used for the widened roadway shoulders. On the project, Norris Asphalt used paving asphalt PG 58- 28 – a Performance Graded (PG) asphalt derived from select- ed crude oils via a carefully controlled refi ning process. The 58-28 refers to a Celsius temperature range: 58C or 136.4F to -28C or -18F. "Our paving on this project went quite well," Mobley said. "We were using a new machine – a Roadtec RP-195e, which is a powerful, rubber-track paver made for highway work." Norris Asphalt received delivery of the new paver in time to use on the Iowa Highway 92 project. "Roadtec guys showed up to train us on our RP-195e and after a few minutes we basically said, 'Not to be rude, but get out of our way … we have work to be done,'" Mobley says. "The machine is easy to learn and operate." Mobley says he likes the way the paver steers with its joy- stick steering and prefers the heavy 40-foot drag screed to no- contact screeds he's seen on other machines. He mentioned that the dual operator stations can move out beyond the sides of the machine to give the operator a clear view down the sides of the paver. And he likes that the machine is a tread paver. "Unlike wheel pavers, we get stability even when laying down asphalt on three-inches of choke stone," Mobley notes. "We get more uniform results with a track paver and there's a smoother ride as a machine operator. The RP-195e has excep- tional rideability." Norris Asphalt Paving owns a 2004 Roadtec RP-195 asphalt paver, which probably helps explain the crew's immediate comfort with the new paver. "Although the new paver has some great features our older model doesn't, but I will never give up the 2004 RP-195," Mobley says. "We've paved some incredible roads with it – two of which ended up in the top fi ve for the Sheldon G. Hayes Award; it hits all the critical factors for quality paving results. I can see already that our new Roadtec paver will per- form as well." Project highlights As Norris Asphalt comes to the end of the Iowa Highway 92 project, Mobley identifi ed a few things about the project he'll remember most. "This was our fi rst time using the RP-195e asphalt paver and the machine helped us get done quickly and with the quality results we wanted," he says. The new paver was delivered from the factory all set up without a need for any adjustments. The machine, which came equipped with the Guardian Telematics System, proved to be useful with staying on track. Mobley says his team starts out with a very early workday. One morning, the machine started up and idled, but wouldn't rev up. "I called, not expecting anyone to be available that early, and got through to support immediately," Mobley says. "I explained what was happening. They said: 'Let us get into your machine on our end and see what the problem is.' They called back in 20 minutes and said, 'Fixed.'" The 16-plus-mile stretch of Iowa Highway 92 is but one chunk of the 275-mile state highway that runs from east to west across the state. The work that Norris Asphalt Paving Co. performed on the project was subject to the Iowa DOT's Quality Management – Asphalt (QM-A) program, which holds the contractor responsible for mix design, sampling, testing and making mix adjustments if necessary. In other words, contractors assumed start-to-fi nish responsibility for the product they produce and place. Norris Asphalt's fi nished road passed all of the I-DOT ran- dom density core tests, which check for voids. The fi nished asphalt paved surface achieved impressive profi lograph- measured 12.61 to 12.9 International Roughness Index (IRI) scores. When asked how they were able to achieve, what many would consider, exceptional IRI scores on the fi nished paved surface, Mobley said: "Superb paving machine and darn good crew!" For the I-DOT offi cials signing off on the work, there is a confi dence that the highway section is good to go for at least a 20-year life.

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