NCPA - Nebraska Concrete Paving NCPA Summer 2015 Hello again! Time for another newsletter from the...
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Nebraska Concrete Paving Association NCPA Summer 2015
Hello again! Time for another newsletter from the NCPA!
First, thank you to the people that helped us at the Concrete Paving Workshop. We served 350 for the Awards Lunch and had almost 400 people attend the workshop. Pictures of the Paving Award Winners appear later in the newsletter.
Brian Schmidt from Crete won the Raffle Prize, a 22 caliber Henry Golden Boy rifle. Congratulations to Brian!
We are adding new paving award categories for the 2016 Concrete Paving Workshop. They are:
• County Roads (making them separate from State Secondary Roads)
• General Aviation Airports • Concrete Overlays
We will have at least four concrete overlays placed this year. They are:
• US 30 from Gothenburg west • The Darr Bridge Road in Dawson County • Part of Cunningham Road in Douglas County • 535th Road just north of Fullerton
Surprisingly, asphalt prices have not followed the downward price trend that crude oil and gasoline exhibited. Prices are still running in the $550 to $700 price range, depending on oil grade.
Concrete prices are up about 5% nationwide.
Twelve from Nebraska visited the MnRoad test track in June. More later in the newsletter.
And just a reminder, we moved from our old office on Cornhusker Highway to a new office at 5700 Seward Avenue in Lincoln. Stop by and see our new digs!
Some save-the-date items:
• The next Concrete Paving Workshop is Tuesday and Wednesday, January 19-20, 2016.
• The NC&AA Golf outing at the York Country Club August 3rd.
• The NC&AA Scholarship Fund Shoot at the Oak Creek Sporting Club near Brainard October 6.
• Concrete Cares at the Archway in Kearney September 27th.
Bill Cook, P.E.. NCPA Executive Director
Education and Research at the MnRoad Test Track On June 10, 11, and 12, thirteen of us travelled to Minneapolis and Albertville, Minnesota to review the MnRoad Test Track and the research occurring at the Test Track.
The MnROAD test track was initially constructed between 1991-1993 and is one of the most sophisticated, independently operated pavement test facilities of its type in the world.
Story inside . . .
2 Concrete for Life News Summer 2015
The test track consists of three unique road segments made up of nearly sixty, 500 foot test sections:
Ø 3.5-mile Mainline Interstate roadway with “live” traffic (29,000 vehicles /day with 13% trucks with an Annual ESAL loading of about 1,000,000 ESALs in the driving lane and about 280,000 ESALs in the passing lane).
Ø 3.5-mile bypass interstate roadway carrying “live” traffic when not on the mainline.
Ø 2.5-mile closed-loop, Low-volume roadway loaded with an 80,000 pound 5-axle tractor trailer. The inside lane of the closed-loop roadway has carried 486,211 ESALs from 1994 through 2013.
The Test Track has done real world research applications for PCC overlays, basic PCC thickness design, recycled unbound pavement materials, composite pavement
Education and Research at the MnRoad Test Track
Pictured (L to R): Jereme Montgomery; Tim Hegeholz; Tom Burnham (MnRoad); Kevin Domogalla; Dr. Bernard Izevbekhai (MnRoad); Tim Weander; Ben Worel; Jeff Thompson; Dr. George Morcous; Tyler Jensen; Jason Volz; Keith Meyer; Andy Dearmont; Jason Lehn.
continued from page 1
studies, pervious concrete pavement studies, surface characteristics of PCC and HMA pavements, warm mix asphalt, low temperature cracking of HMA, and preventive maintenance of HMA pavements.
A newer test section includes using roller compacted concrete on shoulders, and for pavement patching.
We saw three pavement sections of I-94 that were placed in service in 1992. The sections consists of a 7.5” PCC dowelled pavement on top of a four-inch permeable asphalt base on top of a three-inch dense granular base on clay subgrade. The sections differ mainly by the joint spacings. Currently these three sections are being used on I-94 to test three types of pavement grinding for noise, friction, and splash. These three sections are providing service to about 29,000 vehicles daily, including about 13% trucks for an annual truck loading of about 1,000,000 ESALs each year in the driving lane.
For more information about MnRoad, see the website at: http://www.dot.state.mn.us/mnroad/
Thanks to Ben Worel and the MnRoad staff for the time they spent with us, and for closing the mainline of I-94 so we could review it.
Summer 2015 Concrete for Life News 3
New methods, con-cepts, materials and even new terminolo-gy are changing how concrete overlays are being promoted, designed and built.
The industry has developed an op- timal joint configuration for concrete overlays, 6x6x6 for short, describ- ing panels that are 6 feet long by 6 feet wide by 6 inches thick. This standard configuration minimizes moment axle loadings, which in turn, reduces slab curling. While not completely universal this configura- tion is applicable for a wide array of projects from the national highway system to county roads.
And so the term “ultra thin whitetopping” is out. BCOA, for
bonded concrete overlay of asphalt, is in. BCOAs are one of five freshly designated variations of concrete overlay designs.
New materials support an em- phasis on optimum durability rather than compressive strengths. A new emphasis on closely gauging matu- rity of fresh placements – opposed to accelerated curing – is changing how quickly concrete overlays are opened to traffic.
For example, in a 2014 Transpor- tation Research Board paper, au- thors Kivi, Tighe, Fung and Grajek cite the example of Toronto.1 The city attacked rutting and shoving problems that refused to respond to regular maintenance. Their research showed concrete overlays
and inlays are excellent rehabilita- tion options for urban pavements subjected to volumes of traffic. “The pavements are in very good condi- tion visually, ride quality remains excellent and the recurrence of the regular rutting and shoving prob- lems that were being observed prior to rehabilitation has been mitigat- ed,” the authors say.
6x6x6 = SUCCESS FOR CONCRETE OVERLAYS
Unbonded concrete overlay on concrete (UCOC) is placed on milled asphalt pavement.
road science | by Tom Kuennen
EquipmentWorld.com | March 2015 49
1 Rehabilitating Urban Pavements with Con- crete: A Municipal Case Study by Aleks Kivi and Susan L. Tighe, PhD, P.Eng, Department of Civil and Environmental Engineering, Univer- sity of Waterloo, Rico Fung, P.Eng, Cement As- sociation of Canada, and Jozef Grajek, M.Sc., P.Eng, City of Toronto, Ontario (TRB, 2014).
Reprinted courtesy of Equipment World
4 Concrete for Life News Summer 2015
‘Thin’ remains ‘in’ Thinner overlays of portland ce- ment concrete remain a high prior- ity for the concrete paving industry, but while hyperthin PCC overlays have been placed as pavement preservation measures, they are uncommon and most overlays don’t approach the thinness of as little as 1 or 2 inches the National Asphalt Pavement Association is promoting with Thinlay.
“There are no hard and fast rules as to what’s thin or not, but I would say 4 to 6 inches constitutes the thinner side of what we do,” said Jerry Voigt,
president and CEO, American Con- crete Pavement Association.
He added the volume of these thin- ner concrete overlays has increased in recent years. “Our volume of paving fluctuates every year, and we monitor that,” Voigt told Equipment World. “We also monitor overlays, and we now are between 10 to 15 percent of our total volume of paving now in concrete overlays. Eight to 10 years ago it was less than 5 percent, so we are excited about that growth. And half of today’s overlay volume is 6 inches or less.”
Also, ACPA has seen a dramatic change in application of overlays.
“We’ve seen a shift in concrete overlay placement,” Voigt said. “They used to take place mostly over concrete. Now they’re mostly over asphalt. Some two-thirds of the con- crete overlays being placed are going down on asphalt pavements.”
Why the growth in concrete over- lays? “Agencies can’t reconstruct ev- erything that they might want to, so they are looking at different options for pavements,” Voigt said. “And they have been turning to the option of concrete overlays more than they have before.”
This growth in thinner concrete overlays takes place as the industry refines designs and terminology. “In the day, we used the term ultrathin whitetopping, which generally was used for concrete on asphalt,” Voigt said. “People still use those terms, but we have de-emphasized them. We prefer to talk about concrete overlays being bonded or unbond- ed, or on concrete or on asphalt.”
This has led to new terms describ- ing concrete overlays: • BCOA, bonded concrete overlay
on asphalt, formerly called thin or ultrathin whitetopping
• BCOC, bonded concrete overlay on concrete
• UCOA, unbonded concrete over- lay on asphalt
• UCOC, unbonded concrete over- lay on concrete, and
• Bonded or unbonded concrete overlay on composite pavement (usually asphalt cap over concrete). In general, bonded concrete over-
lays over asphalt will be thinner, and unbonde