Better Roads

June 2014

Better Roads Digital Magazine

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Better Roads June 2014 17 HighwayContractor A system that allows detection of thermal segrega- tion in the asphalt mat – in real time – and re- cords a thermal profi le is being used now by some state Departments of Transportation to eliminate inconsis- tent densities because freshly paved asphalt pavement did not compact properly after becoming too cool and the low temperatures contributed to these low densities. "We like that it's something we can give to them that they can use in real time while they're paving, to make adjust- ments in their operations," Johnson says. "We'll get a better asphalt pavement because our spec currently calls for using cores for density. And we do that a day later. So if there is something going wrong that you can do to improve the pavement in real time, rather than by checking it a day later – we think that's a good thing." The system's basic components are composed of a bar mounted across the rear of a paver with 12 or more infrared thermometers attached, an on-board computer, a distance encoder, and an optional GPS antenna. The infrared thermometers measure mat temperature at user-defi ned intervals as the paver moves along. The computer records those temperatures and matches them to distance measure- ments taken by the distance encoder or the GPS system. In addition to displaying real-time mat temperature data on the computer screen for the operator or quality control manager, the system can provide a detailed, color-coded thermal profi le, foot by foot, of your asphalt mat. The pro- fi le can be stored in a memory stick or sent to the cloud, where it can be accessed through the Internet. A contractor can email reports directly to a state DOT at the end of each by Daniel C. Brown, Contributing Editor A Pave IR bar provided a thermal profi le for this mill and overlay project done in October of 2013 by Hardrives Inc. of Rogers, Minnesota, on TH 494 in Bloomington, Minnesota. Photo courtesy of Minnesota Department of Transportation A temperature bar can provide a thermal profile in real time. Fighting Thermal Segregation HighwayContractor_BR0614.indd 17 6/2/14 10:21 AM

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