Checking the newly laid strip is (L-R): Bruce Batzer, president of Astech Corp.; Richard Kramer, Roadtec demo & training specialist (kneeling); Dave Miller, regional sales manager; Paul Nolan, research project manager MnDOT; and Ed Johnson, research engineer MnDOT.
putting down the thin lifts this way are many. No trucks, material transfer vehicles or paver tracks contaminate or take the emulsion away from the cleaned, sprayed road surface if done conventionally. No vehicular traffic picks up the tack coat in the wheel rut surface since the tack coat is sprayed just inches in front of the asphalt being placed by the augers. “When the asphalt hits the oil, it immediately steams the water out of the oil, which makes it bond extremely fast to the surface you are paving. It also pulls part of the oil up into the asphalt that you are laying and creates a super adhesive bond that establishes a good durable product on the road. The 1 shot rate can be varied based upon your needs and emulsion width is more precise to just where the asphalt is being placed,” explains Dave Bussard, service and field technician for Roadtec. Bussard was part of a group of five Roadtec technicians, spearheaded by Richard Kramer, to make sure their equipment would be running properly during all different test mixes and methods. Local contractor, Astech Corp. (Asphalt Surface Technologies Corp.) of St. Cloud donated its SB2500 Shuttle Buggy to feed the Spray Paver SP-200e during the hot mix test session. Even though it was done during the firm’s short paving season, President Bruce Batzer felt the need to contribute what he could, since he would benefit from what was being done in his area of work. As a pavement preservation company who works in Minnesota and the surrounding states with micro surfacing crews, crack repair crews, and the ultra-thin bonded wear course crews, Batzer realizes the need for improved roads. He also provided his crews to direct traffic, including a pilot car on the low volume road of CR-8.
2 Hardrives Inc. of St Cloud and Becker, MN used its 350-ton asphalt plant to make the 13 different mixes with different designs from UTBWC, ARB, OGFC, Virgin, to HiMA, 32 tons at a time. Hardrives’ drivers made sure that both NCAT and MnDOT received samples of each mix for further testing, as to determine that each mix was spoton according to specific formulation. Even after a 45-minute haul trip, asphalt mixes ranged in the 246º to 258º F temperature range. Sakai America contributed two doubledrum rollers for the duration, along with District Manager David Koerkenmeier guiding and instructing operators on the use of the SW 770HF (67-in. width) and SW 654 (58in. width) rollers that would final compact the newly laid asphalt. Caterpillar donated its rubber-tired CW 34 wheel roller as well. Collaborative Aggregates is sponsoring a Delta S applied research section at both climate locations to provide them real traffic, cold weather climate, asphalt pavement performance data points compared to the more
1: A 3/4-in. thin layer of asphalt is laid over the same width of tack coat with the Spray Paver. 2: Two different asphalt mixes are placed continuously on route CR-8. (L) RAS with nominal maximum aggregate and (R) virgin thin mat.
temperate climate conditions offered at the Alabama location. That information will be eventually disseminated and used worldwide.
Lower life cycle costs Currently, about 19 states are sponsoring these projects, more than half a dozen from northern states. Yet all states can benefit from these experiments and written results. “We’ve never been able to provide guidance to the state DOTs on thermal cracking and snow plow damage because that’s unique to the climates that are up in the extreme north," says Buzz Powell, assistant director at the NCAT. "So what we’re doing is
December 2016 • www.ForConstructionPros.com/Asphalt • Asphalt Contractor
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