Minnesota Department of Transportation

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Road Research


Orange barrels on a highway

NCAT/MnROAD Fall Sponsor Meeting

At the end of September, the National Center for Asphalt Technology and MnROAD celebrated their partnership with the annual Fall Sponsor Meeting. Here are some of the highlights.

Associate Profile: Concrete Paving Association of Minnesota

For the concrete industry, the magic is in the mix these days, according to Matt Zeller, executive director of CPAM. He and his organization are looking at technologies and experiments that will help them shape the direction of concrete pavements across Minnesota and the country. In particular, some of the NRRA test cells at MnROAD show promise to change how we think about concrete pavements.

The first mix is a fiber-reinforced pavement (and overlay) that is already testing how thin researchers can make a concrete pavement and have it hold up. MnDOT is also installing fiber-reinforced concrete projects at Hwy 63, north of Rochester and Winona County Rd. 25, from Lewiston to Rollingstone. Both projects have a 5-inch overlay.

Experimenting with different concrete thicknesses is central to CPAM. For example, says Zeller, if you increase your overlay from 4 inches to 5 inches, you will get twice the lifespan on that section of road for one extra inch of concrete. On the other hand, if you have a great base and sub base, sometimes you can get away with less, he says. They’ve had luck with concrete overlays 3 inches thick, for example, but the structure and asphalt have to be in very good shape.

It used to be conventional wisdom that “concrete has got to be 8 inches thick--it’s just what it needs to be. We’ve got 6 inches out at MnROAD that’s been there for over 20 years on the interstate—one of the highest trafficked interstates,” says Zeller.

He also wants to test conventional wisdom about when you can open a concrete road to traffic. At MnROAD last year they tested this by driving a snowplow and a pickup truck on new concrete at different times to see how much damage is done to the structure. Zeller hopes this research will “allow us to open the road to locals and business that much sooner.” Currently, paving contractors wait 2-3 days before opening a concrete road to traffic.

Finally, there is the experiment at MnROAD featuring various low cementitious mixes. This, says Zeller, promises to be very good for the environment if it works. “There’s so much out there on the sustainability and environmental efforts, if we can take 50 or 100 pounds of cement out of our mixes, that’s huge,” he says. They are also trying this on the shoulders on I-90 in Minnesota. Of course, he adds, if you build a concrete road well, it can last a long time and that’s more sustainable and better for the environment too.

Associate Profile: Minnesota Asphalt Paving Association

MAPA has gone through a lot of changes the past year, one of them being a new executive director, Abbey Bryduck. It’s also deep in the planning and finalizing stages for its annual member meeting in December 6.

Aside from its immediate concerns, MAPA’s long-term vision is concentrating on the workforce of the future, in particular the paving and construction workforce, says Brandon Brever, associate director of MAPA.

There’s little debate that the technological tools for constructing asphalt roads have been getting more sophisticated. With thermal imaging, ground penetrating radar, intelligent compaction and many more advances in paving technologies, we are going to need a workforce who can handle these tools. That means great training, in high school and beyond, a lots of it.

One of MAPA’s members, Duininck, is currently reaching out to high school students and working with schools to shape a curriculum that can build this workforce of the future.

On the other hand, Brever is encouraged by the technology he is seeing. Much of it “on the front end, for the guys actually using it, it’s very intuitive, easy to pick up,” he says. An example of that is intelligent compaction. With roller mapping, Brever says, it’s much easier to train roller operators because they can instantly see on the screen the passes they’ve made. That leaves less room for operator error.

So along with training, Brever hopes to see more technologies that not only improve the workmanship of the pavements but also are designed to be used by workers who won’t have to spend a lot of time calibrating or fixing bugs.

The workforce is the human side of the equation. But there is also the mix side of the asphalt equation, and Brever is very encouraged by what he sees. The use of polymers in asphalt mixes is particularly important, he says. “I don’t even know if we’ve seen the long term impacts of that and how well some of those are holding up,” says Brever.

Finally there is the data. All of these technologies, designed to improve the construction of pavements, generate a lot of data. Tangled up in all that data are answers about what actually contributes to the life cycle of pavement, says Brever. The industry’s challenge is to communicate all of that data into a cohesive system. The Veta system (a MnDOT-led pooled fund research effort), he says, is going in the right direction, as long as we can keep it easy to use for contractors.

Research Pays Off October

Please join us for these upcoming webinars.

Oct. 16: Development of Energy-, Cost-, and Environment-Based Life-Cycle Tool for In-Place Recycling Methods: Professors Hasan Ozer and Imad Al-Qadi, University of Illinois at Urbana-Champaign.

Summary: The webinar will introduce the life-cycle assessment (LCA) tool developed for Federal Highway Administration (FHWA) to evaluate energy consumption and environmental impacts of in-place recycling techniques. The tool was developed consistent with the FHWA’s pavement LCA framework for the use of local and state highway agencies to make comparative assessment of in-place recycling techniques with their conventional alternatives. A comprehensive inventory database was developed through inventory modeling and data collection from contractors and agencies. The tool provides a user-friendly platform for state and local agencies to make life-cycle based decisions for selecting in-place recycling alternatives. Case studies will be presented to illustrate the potential use cases of the tool.

Nov. 20: NRRA Teams Review 2017 projects one year out (the time of this webinar will extend beyond the traditional hour to accommodate all the teams and information)

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