Every 3rd Tuesday of the month, 10:00 a.m. (CST), Minnesota Department of Transportation (MnDOT)’s MnROAD provides a monthly seminar to highlight research topics that will make an impact on the work done here in the state of Minnesota and around the country.
2020 Upcoming Webinars:
February 18, 2020:
Evaluation of Long-Term Impacts of Early Opening of Concrete Pavements
by Lev Khazanovich, University of Pittsburgh
The presentation provides an update on the performance evaluation of four MnROAD concrete pavement cells loaded several hours after concrete placement. The cells did not exhibit any visible damage and the analysis of the data collected by the MnROAD personnel could not identify any damage associated with the early loading. The preliminary results of this study suggest that concrete pavements can be opened to a light traffic significantly earlier than required by the current strength opening criteria.
Project Summary—This project will help to establish a method for determining when a Portland Cement Concrete (PCC) pavement or patch can be opened earliest to traffic without compromising its long-term performance. To achieve it, the very early-age fatigue damage and associated long-term distress in PCC pavement subjected to early opening will be evaluated and monitored. This will verify early-opening methodologies recent research has proposed. The objectives of this study will be:
• Evaluate visible and non-visible immediate and long-term damage caused by early age loading. To achieve it, a comprehensive analysis of sensor reading and non-destructive test results should be conducted.
• Quantify the effect of early loading damage on long-term performance.
• Determine minimum strength at opening or other measurable variables associated with this parameter.
• Recommend strategies for minimizing or avoiding early loading damage detrimental to long-term performance.
To JOIN this WEBINAR via SKYPE, for project tasks/statuses, final project report, and more information, please go to: www.dot.state.mn.us/mnroad/nrra/structure-teams/rigid/longterm3.html
March 17, 2020:
Effective Concrete Partial Depth Joint Repairs review
by Heidi Olson, Braun Intertec
Project Summary—Although only small areas are often involved, the joint distress can substantially disrupt traffic flow and increase pavement roughness sacrificing consumer ride comfort. Furthermore, secondary distresses and degradation of otherwise sound concrete can occur due to poor joint conditions.
Joint distress can range from minor spalling that requires no immediate action to major distresses that can affect large areas of the pavement and significantly disrupt traffic. When immediate action is required, temporary repairs are often made using readily available materials, such as cold mix or other asphalt materials. These temporary materials are oftentimes replaced at a later date with more permanent materials to re-establish the integrity and functionality of the concrete pavement.
When longer-lasting materials are used in the initial joint repairs, the impact to travelers is reduced and additional costs for temporary materials and subsequent removals are eliminated. Different material types are available for longer-term repairs which vary widely in cost, required skill level for satisfactory placement, and time needed before opening to traffic. The performance of each of these materials can also vary widely making selection and installation of permanent repairs challenging.
Traditionally, joint repairs have been assumed to last 6 to 8 years, but some agencies have experienced patch service life in excess of 20 years. With the range of products available and performance periods experienced, there is a need to determine the current state-of-the-practice.
The goal of this project is for the Contractor to provide a guide for State and other agencies to establish an effective joint repair program. The final report will guide State through product selection, installation techniques, equipment needed for completing the repair, typical performance cost, along with the life expectancy of the repair products.
Longer lasting patches on Minnesota’s PCC pavements will reduce the need for lane closures, user delays and safety concerns, reduce PCC pavement maintenance costs, and increase availability of State District Maintenance staff to perform other duties.
To JOIN this WEBINAR via SKYPE, for project tasks/statuses, final project report, and more information, please go to: www.dot.state.mn.us/mnroad/nrra/structure-teams/preventive-maintenance/longterm2.html
April 21, 2020:
Performance Benefits of Fiber-Reinforced Thin Concrete Pavement and Overlays
by Manik Barman, University of Minnesota – Duluth
Project Summary—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 fiber reinforced concrete 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 and 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.
To achieve this, the NRRA has designed and constructed 7 fiber-reinforced concrete test cells and one control plain concrete cell at the MnROAD facility in summer 2017. The primary variables in these cells include panel thickness, type of support (base), panel size, and fiber dosage. All of these cells are equipped with different types of response measuring sensors. Performance of these cells will be periodically evaluated. Sensor data and periodically collected performance data will be used to achieve the following objectives:
- Determining contribution of fibers in reducing panel fatigue cracking;
- Determining contribution of fibers in mitigating joint faulting;
- Determining optimal panel size.
To JOIN this WEBINAR via SKYPE, for project tasks/statuses, final project report, and more information, please go to: www.dot.state.mn.us/mnroad/nrra/structure-teams/rigid/longterm2.html
May 19, 2020:
Month off for Pavement Workshop
For more information and past webinars available to view any time (YouTube), please go to: www.dot.state.mn.us/mnroad/researchpaysoff/index.html?utm_content=&utm_medium=email&utm_name=&utm_source=govdelivery&utm_term=