For the concrete industry, the magic is in the mix these days, according to Matt Zeller, Executive Director-Concrete Pavement Association of Minnesota (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 National Road Research Alliance (NRRA) test cells at Minnesota ROAD (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 last 20+ years. Minnesota Department of Transportation (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. Zeller stated, for example, 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.
On the MnROAD side, it’s been a great playground for me and people who like to try new things on roads. It’s so awesome to have a spot where it’s Ok to fail. When we fail, we learn something, and we can apply it.
—Matt Zeller, Executive Director-CPAM
It used to be conventional wisdom that “concrete HAS to be 8 inches thick—it’s just what it needs to be. We have 6 inches out at MnROAD that has 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 said he 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 is 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 said. 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, it’s more sustainable, and better for the environment, too.
For the CPAM link titled “Associate Profile: Concrete Paving Association of Minnesota”, please go to: please go to: http://www.dot.state.mn.us/mnroad/nrra/newsletter/currentissue.html?utm_content=&utm_medium=email&utm_name=&utm_source=govdelivery&utm_term=
For the link to the ongoing project summary report titled “Performance Benefits of Fiber-Reinforced Thin Concrete Pavement and Overlays”, please go to: http://www.dot.state.mn.us/mnroad/nrra/structureandteams/rigid/longterm2.html
For the link to the ongoing project summary report titled “Evaluation of Long-Term Impacts of Early Opening of Concrete Pavements”, please go to: http://www.dot.state.mn.us/mnroad/nrra/structureandteams/rigid/longterm3.html