CANCELED: 2021 NRRA Pavement Workshop
– Minneapolis Area or Online –
September 13-15, 2021:
Mon. Sep. 13: NRRA Day
Tue. Sep. 14: NRRA Day & Vendor Booth
Wed. Sep. 15: Open House Day
Each spring, the NRRA has hosted a multi-day workshop for its members, students of pavement engineering, and other interested parties, but changing guidelines and mandates for Minnesota State Agencies with the increasing cases of COVID meant we needed to hold on sending out registration. After feedback from the Executive Committee, we have decided to pivot once more on this year’s workshop.
NRRA will NOT be having the planned meeting in-person OR online during those days. Instead, the chosen Team projects will present during the next several months of Research Pays Off. These project leads will be contacted shortly.
Save the Date: MN Transportation Conference & Expo, March 1-2, 2022
ALSO: The virtual NCAT Fall Sponsor Meeting will be held October 19 & 20, 2021. Please put it on your calendar. A preliminary agenda will be sent out in September.
For more information to come on the Pavement Workshop page, please go to: www.dot.state.mn.us/mnroad/nrra/index.html
Report:
Click to go to PDF of Report, and to enlarge NRRA and MnRoad
“Performance Benefits of Fiber-Reinforced Thin Concrete Pavement & Overlays”
Project Start Date: October 27, 2017 | Project End Date: June 30, 2021:
Due to increasing budget constraints, there is interest in economizing pavement structures by reducing the panel thickness or increasing the service life of the pavement. Past research has demonstrated definite limits to reducing the panel thickness of conventional undoweled jointed plain concrete pavement (JPCP), thus invoking interest in understanding the potential of using structural fiber-reinforced concrete (FRC) to either allow slab thickness reduction or an increase in service life. The research need arises in understanding the contribution of structural fibers in mitigating panel fatigue cracking and transverse joint faulting in thin concrete overlays and pavement on grade. There is interest in understanding the effects FRCs have on panel size as well, especially for much thinner slabs.
Structural fibers generally improve the performance of thin concrete pavement and overlays by (i) holding cracks tight and (ii) transferring the wheel load between adjacent slabs. Several laboratory studies are currently in progress to comprehensively quantify the above-mentioned two benefits. Performance comparison of companion pavement sections—with & without fibers—are now required to obtain a field-validated method to accurately account for the contribution of fibers for the future mechanistic-empirical (ME) design procedures of FRC based thin concrete overlays and pavements on grade.
This 3-year study (2017 to 2020; report 2021
investigates the performance benefits of
synthetic structural fibers in mitigating distresses in
thin concrete pavements & overlays constructed at the
Minnesota Road Research (MnROAD) facility.
In this study:
• 2 ultra-thin concrete pavements placed on a gravel base 3″ and 4″ inches thick
• 4 thin 5″ and 6″ thick placed on an existing concrete pavement
• 2 thin unbonded concrete overlay cells 5″ thick placed on an existing concrete pavement
Report discusses:
• objectives of the research
• methodology of the research
• construction of the test cells
• instrumentation
• traffic load application
• data collection
• analysis procedures
• structural responses and distresses observed over 3 years; sensor data; and collected performance data used were discussed and compared … to achieve the following objectives:
—fatigue cracking
—faulting
—joint performance measured in each cell
Primary variables in these cells include:
• panel thickness
• type of support (base)
• determining optimal panel size
• fiber dosage:
—determining contribution of fibers in reducing panel fatigue cracking
—determine contribution of fibers in mitigating joint faulting
• different types of response measuring sensors
• periodic evaluation of performance
The report discusses the objectives and methodology of the research—including the construction of the:
• test cells
• instrumentation
• traffic load application
• data collection
• analysis procedures
For the full report, please click on cover page above, or go to: www.dot.state.mn.us/mnroad/nrra/structure-teams/rigid/files/rigid-lt2-frc-task-6-7-final-report-2021-06-28.pdf
For the MnRoad project summary, and the “Fiber-Reinforced Concrete Pavements” (doc)(2014), please go to: www.dot.state.mn.us/mnroad/nrra/structure-teams/rigid/longterm2.html
Home photo: Photograph of the fibers used in MnROAD 2017 FRC test cells
NRRA UPDATE:
Click to enlarge each: 9-states MAP and
Sequencing of the Phase II deployment with test section construction occurring in May 2022
The NRRA is a State-Sponsored Pooled Fund with the goal to improve the future sustainability of our roads through research and a commitment to cooperative implementation. The alliance sponsors research at the MnROAD test track, one of the most sophisticated cold-weather pavement facilities in existence, as well as other locations. The 9 pooled fund states are indicated in the map above (click to enlarge). The pooled fund includes:
• Industry
• University
• Consulting partners
Phase I of the NRRA field activities concluded in January 2021
Phase II began seamlessly in February 2021
—NRRA focus narrowed to the 2 priorities of sustainability and application of intelligent construction technologies for all pavement projects
—4 concrete-related projects were selected for testing as indicated below:
• Reduced Cement in Concrete
• Alternative Cementitious Materials
• Use of Carbon Dioxide in Concrete Pavements
• Related Idea: Flooding Pavements Assessment App-Phase II
Research Pays Off Recordings
In June 2021, NRRA experienced some technical difficulties with Webex during RPO … no one was able to join! Thanks to attendees’ flexibility, they moved over to Teams to hear from Heather Dylla of FHWA. The recording and July session are available online now.
Check out NRRA YouTube channel, subscribe, and click the bell to be notified when new uploads are live: For the NRRA YouTube Channel with all “Research Pays Off Recordings”, please go to: www.youtube.com/channel/UCPqdt93L6aIOyPDCLiHvDug
For helpful links, please go to:
NRRA: www.dot.state.mn.us/mnroad/nrra/index.html
MnROAD: www.dot.state.mn.us/mnroad/index.html