Maintenance crews on Hwy 53 in St. Paul


Minnesota's Cold Weather Road Research Facility

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Phase II Research Projects (2007-2015)

The MnROAD Phase II research initiative combines multi-state funded pooled projects, research initiatives led by public and private partners, and international research.




HMA Surface Characteristics related to Ride, Texture, Friction and Durability

There is need to conduct controlled experiments in Northern climates to determine the durability and performance of pavements built for certain surface characteristics. Because of the attention that has been accorded to Hot Mix Asphalt new surface characteristic specifications have begun to be tested. The aim of this MnROAD research is to satisfy both the surface characteristics and the need for strong pavements in cold weather.

HMA Surface Characteristics Research Page


Investigation of Low Temperature Cracking in Asphalt Pavements - Phase II

Low temperature cracking is the most prevalent distress found in asphalt pavements built in cold weather climates. Low Temperatures cause the pavement to shrink, tensile stresses to build and cracks to form. To help prevent this damaging issue it is very important to understand the mechanism of crack initiation and propagation.

The goal of this project was to evaluate different laboratory procedures, material properties and pavement features in order to develop an optimal system for selecting low temperature crack resistant materials. Three sections constructed at MnROAD research facility provided experimental field data for this research.

Low Temperature Cracking Research Page


MnROAD Field Investigation of Polyphosphoric Acid Modified Asphalt

This MnROAD study built upon the findings of previous Federal Highway Administration research to conduct a field trial assessing the performance of Polyphosphoric Acid (PPA) over a 5-year period. PPA has been used for 30 years to stiffen asphalt pavement. Recent research by the FHWA and MnROAD hope to establish mutual cost- effectiveness and asphalt strength to provide a better utilization method for PPA.

PPA Modified Asphalt Research Page


Taconite Usage in Pavement Applications

Taconite aggregates are a potential new source for virgin paving aggregates that are currently in high demand. Limited information is available concerning the quality of taconite as a paving aggregate. This MnROAD research project has utilized the MnROAD research facility to explore taconite aggregate potential.

Taconite Aggregate Project Page


Warm Mix Asphalt

The environmental, health and construction related benefits realized by WMA are well documented but its value to stop Low Temperature Cracking is also of interest to MnROAD researchers. Thermal cracking is the predominant mode of distress of HMA pavements in Minnesota, and it is our hypothesis that the reduced level of oxidation at the mix plant will lead to better long-term pavement performance. We will also monitor other performance measures such as rutting, fatigue cracking, top down cracking, and ride. By placing WMA at MnROAD, the results of the study will be disseminated to a wider audience of city and county engineers, consultants, contractors, and researchers throughout Minnesota and the nation.

WMA Research Page




60- year Design Concrete Pavement - Performance Model Development

Due to increased traffic congestion and reduced highway construction budgets, more emphasis is being placed in designing and constructing longer life pavements. MnDOT has constructed what is believed to be a 60 -year pavement. MnROAD is helping to research this pavement to know if it is a reliable and cost- effective model for Minnesota roadways.


Composite Pavement Systems (SHRP2)

This national research project focused on two promising applications of composite pavement systems : 1). thin asphalt layer(s) over a PCC layer and 2). a PCC surface over a PCC layer to determine the behavior and identify critical material and performance parameters, develop and validate mechanistic- empirical performance models and design procedures consistent with the Mechanistic- Empirical Pavement Design Guide (MEPDG), and recommend specifications, construction techniques and quality management procedures.

Composite Pavements Project Page


Design and Construction Guidelines for Thermally Insulated Concrete Pavements

Thermally insulated concrete pavements consist of concrete pavement structure (jointed or continually reinforced) covered by an asphalt layer during construction or soon after construction to address ride quality or surface characteristic issues. TICPs combine the structural longevity of PCC pavements with the serviceability of HMA pavements. There is no definitive guidelines for effective design and construction based on the understanding of the effects of design, materials and construction parameters.

Thermally Insulated Concrete Project Page


Performance of Thin Unbonded Concrete on High Volume Roads

Due to increased traffic congestion and reduced highway construction budgets, emphasis is now being placed on seeking effective rehabilitation techniques for older pavements. Whitetopping and unbonded concrete overlays have great potential as pavement rehabilitation methods.  Some whitetopping cells have been built previously at MnROAD.  However, the underlying HMA pavements were in good condition and did not represent typical conditions. Researchers and pavement designers still question if the data from these test sections can adequately represent the performance of whitetopping on asphalt pavements that show distress (cracking, rutting).  A new thin whitetopping section built on a full depth bituminous cell in poor condition will be constructed to create a test section to help to answer these questions as well as add to the performance database from which a rational design method for whitetopping will be developed.  The research on this cell will be done as part of a Multi-state Pooled Fund project TPF-5(165) that will use the MnROAD and other test section data to develop a rational design method for thin concrete overlays.

Thin Unbonded Concrete Research Page


PCC Surface Characteristics - Construction

A study of the influence of texture types and texture configurations on various surface performance variables such as tire pavement noise, friction, smoothness, acoustic impedance. Study involves developing measurement techniques and collecting data through these periodic measurements.

PCC Surface Characteristics Construction Research Page


Development of Design Guide for Thin and Ultrathin Concrete Overlays of Existing Asphalt Pavements (Whitetopping)

The one area of deficiency in the application of thin (TCOAP) and Ultrathin (UTCOAP)concrete overlays of existing asphalt pavement (TWT and UTW whitetoppings) is the lack of a unified national design guide. While several local and industry design guides have been formulated, few are based on mechanistic-empirical research born out of actual field performance. To address this issue, many research studies on the accelerated and field performance of TCOAP and UTCOAP are either in progress, or have been recently completed. The Minnesota Road Research (MnROAD) Project has contributed significantly to the understanding of the field performance of TCOAP and UTCOAP. The results from MnROAD and other accelerated loading facilities (ex. FHWA) can now be utilized to develop a unified comprehensive mechanistic-empirical based design method for thin and ultra-thin concrete overlays of existing asphalt pavement.

Thin and Ultrathin Concrete Overlays Research Page


Porous & Pervious


Permeable (HMA) Pavement Performance in Cold Regions

Porous asphalt pavement is an exciting technology in pavement design because of the potential benefits of treating water runoff through the pavement rather than through a storm water system allowing for the reduction or elimination of the need for water detention basins. The objectives of this research are to evaluate the durability, hydrologic characteristics and environmental effects of porous asphalt pavement when used on a low volume roadway in a cold climate. The construction and maintenance procedures will be effectively documented allowing for the best possible data from both the construction and data monitoring.


Pervious Concrete Mix Design for Wearing Course Applications

To date, there have been two key issues that have impeded the use of pervious concrete in the United States, these being: 1) the compressive strengths of pervious concrete have been lower than necessary for required applications and 2) the freeze- thaw durability of pervious concrete has remained suspect. This project will attempt to create adequate strength and durability of pervious concrete and then further test this concrete for such issues as noise and skid resistance. Construction techniques will also be developed to help ease the labor intensive process of construction of pervious concrete.

Pervious Mix Design Research Page


Pervious Concrete Pavement Study

In order to adequately evaluate pervious concrete in this climate, MnROAD has constructed a test section on the Low Volume Road with a proper mix design and instrumentation. This will also provide an operations research advantage as the porosity and infiltration advantage can be monitored over time and standard measurable traffic loads and environmental effects can be measured. This study will to lead and validate pervious concrete pavement designs as a pollution reduction option by minimizing storm water intrusion from developments that are in proximity to wetlands or some trout streams.

Pervious Concrete Pavement Study Research Page




Field Investigation of Highway Base Material Stabilized with High Carbon Fly Ash

The purpose of these test sections is to evaluate the physical and environmental properties of base materials stabilized with high carbon fly ash in comparison to recycled pavement materials and crushed stone. Testing will include aggregate characterization, construction, field testing, and long term monitoring of the test cells.

High Carbon Fly Ash Stabilizer Research Page


Optimal Timing of Preventive Maintenance for Addressing Environmental Aging in HMA Pavements

Preventative maintenance is an important process in the high- level performance of any roadway. A surface treatment should be applied at the proper time to provide a balance between maximum life and minimum cost. This reduces surface aging and protects the integrity of the entire pavement. This MnROAD research project utilizes the MnROAD research facility to gain experimental field data to create a qualitative analysis of how to best maintain HMA pavement quality.

Preventative Maintenance Research Page


PCC Surface Characteristics - Rehabilitation

This research project hopes to better understand concrete pavement surface characteristics and provide tools for engineers to help meet pre-determined requirements for ride quality, quietness, safety against hydroplaning, splash/spray defense and durability. MnROAD is exploring these qualities through Diamond Grinding the surface of the pavement. Variables that play into diamond grinding include blade spacing, depth of cut, kerf configuration, etc. Few of these variables have been studied enough to produce guidelines to create a system of best possible performance.

PCC Surface Characteristics Rehabilitation Research Page


Recycled & FDR


Field Investigation of Highway Base Material Stabilized with High Carbon Fly Ash

The purpose of these test sections is to evaluate the physical and environmental properties of base materials stabilized with high carbon fly ash in comparison to recycled pavement materials and crushed stone. Testing includes aggregate characterization, construction, field testing, and long term monitoring of the test cells.

High Carbon Fly Ash Stabilizer Research Page


Full Depth Reclamation Study

This project compares the characteristics and performance of three reclaimed layers using asphalt emulsion stabilization: 100% RAP, 50% RAP-50% Aggregate base, and 75% RAP-25% Aggregate base. Three MnROAD test cells were constructed to evaluate the properties and performance of full depth reclamations using asphalt emulsion stabilization. The results will be used to develop the best-cost design procedures to achieve the strength and flexibility needed for a pavement.


Recycled Asphalt Pavements

Recycled Asphalt Pavements (RAP) are widely used in pavement construction but practices vary between agencies and there is no consistent, quality method established. Through this MnROAD project, MnDOT hopes to determine if present limits on RAP are justified and help establish a common, qualitative methodology for the various agencies that use this method of pavement construction and reconstruction.

Recycled Asphalt Pavements Research Page


Recycled Unbound Pavement Materials

The objective of this study is to monitor the performance of several test cells at the MnROAD facility constructed using recycled materials in the granular base layers, including blended with virgin materials and 100% recycled asphalt and concrete pavement materials. The material properties are being monitored during construction and throughout the pavement life in order to determine their effects on pavement performance. This will help produce new mechanistic- empirical design procedures with detailed material properties to accurately predict pavement performance.

Recycled Unbound Pavement Research Page


Implements of Husbandry


The Effects of Implements of Husbandry (Farm Equipment) on Pavement Performance

The objectives of this study are to determine the pavement response under various types of agricultural equipment (including the impacts of different tires and additional axles) and to compare this response to that under a typical 5-axle semi tractor-trailer. This was accomplished by constructing new instrumented test sections at MnROAD and by retrofitting instrumentation into the existing test sections. The results may influence policy and legislation in Minnesota and surrounding Midwest states.

Implements of Husbandry Research Page