Better Roads Digital Magazine
Issue link: http://read.dmtmag.com/i/325401
HighwayContractor 18 June 2014 Better Roads day. Reports can show tabular details of temperatures and paver stops. End-of-load thermal segregation is defi nitely visible by colors shown in the profi le. Although the thermal imaging system has seen action in several states in recent years, there are still many states and their contractors, which are not familiar with it. The system was invented by the Texas Transportation Institute (TTI) at Texas A&M University, and was commercialized by MOBA Corp. The Texas DOT has written the Pave IR bar into its specifi cations, and Texas contractors now operate about 50 of the systems. Pilot projects with a temperature bar Minnesota has used the system by including it as a supple- mental agreement beginning in 2009. Last year, the state used a specifi cation and put the temperature bar into con- tracts as a line item. It was used on eight pilot projects last year, and it's slated for use on 20 projects in 2014. "We are looking for uniformity in our construction practices, to get rid of material segregation and thermal segregation," Johnson continues. "We're just trying to get better asphalt densities so that our pavements last the de- sign length of time, or that we get the maximum longevity out of them." This year, MOBA plans to market the next-generation of the system in Minnesota. Instead of a beam that reaches across the width of the back of the paver, the new system will have one central temperature sensor that sweeps back and forth across the mat. "The new system will do exactly the same thing as the beam, except that if a contractor requested to pave wider than one lane, say at 19 or 27 feet, this scanner can handle that without adding extra equip- ment," says Paul Angerhofer, product man- ager of the system for MOBA. "The scanner is only limited by its mechanical range. You would not have to add extra beam exten- sions across the back of the paver." Contractors in Texas do not have the scanner system, mainly because the state's specifi cation has been written for a beam behind the paver carrying a number of sensors. Angerhofer says he will be working with TTI and the Texas DOT to see how the scanner could fi t into their specifi cations. States adjust for cyclic density Meanwhile, other state transportation departments are looking at the Pave IR system with serious interest. The Washington State DOT (WSDOT) has a trial specifi cation for research purposes only, but the state has not attached incentives or penalties to thermal segregation as measured by the system. "WSDOT has used the specifi cation for seven projects," says Jeff Uhlmeyer, state pavement engineer for WSDOT. He says an eighth project is in progress. Five contractors in Washington State have used the Pave IR bar on WSDOT projects and have recognized that the technology can improve asphalt paving quality. "At least on a couple of the projects the contractors took an interest in adjusting their paving operations to reduce cyclic density," Uhlmeyer says. Jim Hedderich, technical marketing specialist with MOBA, says South Carolina implemented a specifi cation last year and Lane Construction completed its fi rst project there with the thermal system. "North Carolina visited their job in South Carolina and is looking at implementa- tion of a spec," Hedderich says. "We have projects coming out in Vermont and New Hampshire this year, requiring both intelligent compaction and the temperature bar. And last year we completed projects in Maine and Pennsylvania and Florida. Oklahoma will do a project this year under the Here, a Pave IR bar helps on a mill and overlay project done in June of 2013 by Ulland Brothers Inc. of Cloquet, Minnesota, on TH 33 near Cloquet, Minnesota. Photo courtesy of Minnesota Department of Transportation HighwayContractor_BR0614.indd 18 6/2/14 10:21 AM