Minnesota Department of Transportation

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Road Research


Orange barrels on a highway

2019 NRRA Pavement Workshop

A message from the Director

  • Both FHWA Vans--asphalt and concrete--will be on hand.
  • We've added an extra day. May 21 will showcase "BIM for Pavements... Asset Management, Planning,┬áDesign and Construction."
  • The reception is being hosted at the showroom of Caterpillar Paving Products

Upcoming Research for NRRA

New research is coming. The five NRRA teams brainstormed ideas, and budgets, for the upcoming years and the projects were finalized by the Executive Committee early in 2019. Some are test sections that will be constructed at MnROAD and elsewhere, while others will be reports that synthesize current best practices. Here’s the research that our alliance will pursue for years four and five of this pooled fund agreement.

Pavement Maintenance

Spray on Rejuvenator Synthesis
This report will be a synthesis of field projects constructed to evaluate spray on rejuvenators, by NRRA members, NCAT, NCHRP, MN cities and counties, and others. It will also include all recent research projects by MoDOT with the ARA. The final report should read as a work plan for the rejuvenator test sections. It will include products to test, tests to run, frequencies, etc.

Spray on Rejuvenator Test Sections
This will be a very detailed study of spray applied rejuvenators on a newer HMA pavement. Testing will include friction, pavement marking reflectivity, and other tests to study the effect of these products. It is expected this will require a significant amount of hours. Traffic control and testing will be the responsibility of the research team. That team will plan and coordinate all aspects of the product installation. Due to the number of products that may be included and the desire to apply them to newer pavements, this study will likely not be at MnROAD--500’ sections are desired.

Service Life Enhancement of Substrates Overlaid with Thin Overlays (UTWBC, Chip Seals & Microsurfacing) for each state
Using the pavement management data from eight National Road Research Alliance member states, we will determine the service lives for the 3 nonstructural overlays. Then we will deduce service life enhancements that these nonstructural overlays contribute to the identified pavement types where the overlays were placed. This research identifies and focuses on the following conventional non-structural overlays.

  • Chip seal
  • Ultrathin bonded wearing course (UTWBC)
  • Microsurfacing, flexible substrates

Intelligent Construction Technologies Team

Evaluation of Levels 3-4 Intelligent Compaction Measurement Values (ICMV) for Soils Subgrade and Aggregate Subbase Compaction

The objective of this project is to:

  • Evaluate Level 3/4 ICMV systems against Level 1/2 ICMV systems for soils and base compaction
  • Develop a blue print for future certification procedures of IC. Field tests will be done though the FHWA.
Support Importing, Viewing and Analysis of Dielectric Constant Data in Veta

This project will add the following features to Veta:

  • Import GPR dielectric constants data files in the AASHTO Intelligent Construction Data Standard Format
  • Calculate the predicted air voids using this data
  • Add data maps, filters and analyses for dielectric constants data and predicted air voids
HD and VHD Seismic Approaches for Roadway Evaluation

The objective of this project is to further verify that this technology can accurately measure the pavement layer (later phases of the work could focus on the base and subbase layers). Then we will attempt to develop a means of taking these measurements while continuously driving.

Rigid Team

Construction Report for Jointless FRC Roundabout in Minnesota

The purpose of this research is to generate a construction report to document the mix design used--along with details about production and placement of the FRC mixture. This project will also monitor and document field performance for the next three years.

Incorporate Joint Faulting Model Into BCOA-ME

This research project will incorporate a faulting model into the existing BCOA-ME program used to design bonded concrete overlays on top of asphalt pavement.

Engineered Dowel and Tie Bars combined with LTPP SPS-2 Determination of Causes for Cracking Over Dowel Bars

The goal of this project is to identify the cause(s) and contributing factors of concrete pavement cracking and delaminating along the plane of dowel and tie bars. This will involve a comprehensive literature review, assessment and summary of instances of this delamination occurring nationally.

Flexible Team

Mix Rejuvenator Synthesis (Phase-1)

This synthesis will summarize the experiences that each NRRA member State has had regarding asphalt mixture rejuvenators. It is intended to share implementation projects to facilitate transfer of knowledge and provide guidance to NRRA Mix Rejuvenator Test Sections (Phase II)

Mix Rejuvenator Test Sections (Phase-II)

Test sections with different mix rejuvenator products will be constructed during summer 2019 in central Minnesota and long-term field performance will be monitored. Details of the project are still being worked out; please contact the NRRA Flexible Team for more information.

Geotech Team

Mechanistic Load Restriction Decision Platform for Pavement Systems Prone to Moisture Variations

A load restriction decision platform will be developed to reliably evaluate pavement bearing capacity and performance. The final product will be a user-friendly tool that will help pavement engineers assess traffic impacts during and after periods of excessive moisture caused by extreme weather or seasonal variations.

Environmental Impacts on the Performance of Pavement Foundation Layers

Seasonal freeze-thaw weakening and changes in saturation due to environmental fluctuations have a significant effect on pavement foundation strength and performance. This project will develop a model to predict frozen soil depth and duration using precipitation, solar radiation, and temperature from existing MnROAD measurements and then estimate the strength and performance of pavement foundation layers subjected to freeze-thaw cycles.

Permeability of Base Aggregate and Sand

This project will quantitatively assess the permeability of granular materials from aggregate base to sand using existing methods validated by a very limited number of laboratory tests. A simple predictive tool will be developed to estimate field permeability using the grain size distribution, crushing percentage, fines content, angularity, and material type.

Improve Material Inputs into Mechanistic Design Properties for Reclaimed HMA Roadways

The stiffness, strength, gradation, and hydraulic conductivity of reclaimed asphalt pavement and recycled concrete aggregate used as base and subbase will be collected from the National Road Research Alliance member states and additional literature. Field and laboratory tests, construction specifications, and pavement performance will be used to recommend input for mechanistic design after a sensitivity analysis has been completed.

Pavement Research Resources

Research Pays Off For May is cancelled due to Pavement Workshop

Research Pays off will resume in June. June's webinar will feature Gerard Moulzolf from AET speaking on 100-year old concrete. July will feature Steve Dickman speaking on Dustex, a new product for base stabilization.

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