The objective of this study is to demonstrate the use of fine and coarse taconite aggregate materials in hot mix asphalt, Portland cement concrete, and other pavement applications for both its constructability and field performance over time. This would help create a greater comfort level for the use of taconite aggregate and help promote its use in the state and around the nation. The specific goal of Task F is to perform laboratory tests on taconite aggregates and on pavements made out of taconite aggregates to establish how these materials will be used in the most appropriate manner for long-lasting roadways. Mn/DOT has the laboratory equipment and expertise to do this required material testing.
This report describes a major enhancement to the Integrated Climatic Model. The Integrated Climatic Model is a one-dimensional coupled heat and moisture flow program that is intended for use in analyzing pavement-soil systems. It has the capability of generating internally realistic patterns of rainfall solar radiation, cloud cover, wind speed, and air temperature to simulate the upper boundary conditions of a pavement-soil system. It has a variety of options for specifying the moisture and temperature, or the flu of these at the lower boundary and at the interface between the subgrade and the base course. It considers the lateral and vertical drainage of the base course m determining the amount of water that enters the subgrade by infiltration through the pavement surface and drainage through the base course. The program calculates the temperature, pore pressure, moisture content and resilient modulus for each node in the profile for the entire analysis period This program also predicts frost behavior, including heave and penetration depth; thermal gradient and curl strain in the pavement layers; and infiltration and drainage behavior of the base course.
The Integrated Climatic Model Version 2.0 has a graphical user interface to model soil-pavement profiles. Through a series of dialog boxes the user inputs all data required for pavement performance calculations. The user may also input climatic data directly from a computer file. After a model run, an interactive dialog box allows the user to generate a wide assortment of output files in both tabular and graphical formats. These output files can be output using the program or can directly be used as input m other graphing software. The Integrated Climatic Model Version 2.0 is intended for use on IBM compatible computers using the Windows 95 or Windows NT 32-bit operating systems. A 486 DX2-66 processor or better is recommended for efficient operation of this program.
With the construction of four new test cells in 2008, the Minnesota Department of Transportation (Mn/DOT) now has six unique pervious pavement test sections at the MnROAD test facility. Recorded temperatures in the pervious pavements and subgrades were compared to impervious Portland Cement Concrete (PCC) test sections over the same time interval. It was found that the subgrade in pervious PCC and Hot Mix Asphalt (HMA) was up to 4 °C warmer in the winter than impervious PCC pavements. The frost depth in an impervious PCC pavement was found to be 45.7 cm deeper than in a pervious PCC pavement of similar thickness. One pervious pavement test cell experienced 60% less freezing cycles over a three year interval than impervious PCC pavements of similar thickness. The air trapped in the pavement voids was suspected to be the main reason for the reduced number of freeze-thaw cycles by creating an insulating effect. In another pervious pavement, entrapped air within the base material may also insulate the pavement from the subgrade.
It is well understood that for heavily loaded concrete pavements, the use of dowel bars across transverse joints can significantly improve their performance. To function effectively, dowel bars must be properly aligned and have sufficient embedment length to transfer stresses to the surrounding concrete. The use of new high accuracy dowel bar location equipment has brought renewed interest to understanding reasonable construction tolerances for dowel bar alignment. The thirteen-year history of pavement performance data from the Minnesota Road Research (MnROAD) facility provides a unique opportunity to examine the effects of dowel bar alignment on joint performance. Specifically, this study investigated the effects of dowel bar embedment length on joint load transfer efficiency. Results of the analysis show that most test cells demonstrate little effect on the overall level and variability of LTE from dowel embedment lengths as low as 10 cm (4 in). Findings of this study could lead to important changes in construction specifications for dowel bar embedment length.
The goal of this research project is to study a road base at the Minnesota Road Research Facility (MnROAD) constructed with high carbon fly ash for long term monitoring of engineering and environmental characteristics. This study will provide a controlled long term evaluation of pavement base materials stabilized with High Carbon Fly Ash
(HCFA). Engineering laboratory testing has shown HCFA to be a viable stabilizing material. Field construction of road test segments is necessary to validate the structural and environmental performance of high carbon fly ash stabilized bases.
This report concerns the results of ongoing environmental chemical analysis of leachate collected from test cells using off-classification HCFA as a stabilizer of road base materials under an asphalt wearing course. This research opportunity is a portion of Phase II of a fly ash stabilization project performed by Bloom Consultants, LLC and is sponsored by the Department of Energy (DOE). The University of Wisconsin-Madison (UW) is a subcontractor of Bloom Consultants and is conducting ongoing evaluations as the project proceeds. Phase II is titled Use of High Carbon Fly Ash to Stabilize Recycled Pavement as Base Course, has a two-year time requirement, and will involve the proposed MnROAD test sections to be constructed in 2007.
The purpose of this report is to provide details on the 2007 reconstruction of several cells on MnROAD's Low Volume Road. As MnROAD enters Phase II of its existence several research projects were initiated that necessitated the reconstruction of pavement test sections. The first research study plans to test various configurations of heavy farm equipment (manure tankers in particular) and assess the resulting damage in comparison to a typical 80,000 lb truck. A new "Farm Road" was built in the MnROAD stockpile area and is comprised of Cells 83 and 84. The second consists of stabilizing a full-depth reclamation base material with off-spec fly ash and comparing its performance to both a non-stabilized FDR and a conventional aggregate base. This study removed Cells 29 and 30 on the LVR and replaced them with Cells 77, 78, and 79. The third study is a field validation of previous laboratory work on polyphosphoric acid modified asphalt binders. It is located on Cells 33, 34, and 35. A fourth study involved innovative diamond grinding of concrete pavements to optimize their surface characteristics (noise, ride, texture, friction, splash and spray). Cells 37, 7, and 8 were ground during the summer of 2007.
Thin and ultra-thin concrete overlays (also known as whitetoppings) are a pavement rehabilitation option that has been increasing in popularity in the U.S. over the past 15 years. One area of deficiency in the use of ultra-thin and thin concrete overlays is the lack of a rational design method. While several local (1,2) and industry (3,4) design methods have been formulated, few are based on mechanistic-empirical research born out of actual field performance. Fortunately, the Minnesota Road Research Project (MnROAD) has contributed significantly to the understanding of the field performance of thin and ultra-thin concrete overlays.
In 1997, three thin (TWT) and three ultra-thin (UTW) concrete overlay test sections were constructed on the interstate portion of the MnROAD facility. The objective in locating these thin concrete surface layers on the interstate was to accelerate traffic related distresses. In 2004, after enduring over 6 million concrete equivalent single axles loads (CESALs), the UTW test sections needed to be replaced due to severe surface distresses. Later that year, four new thin concrete overlay test sections were constructed in their place. Table 1 summarizes the experimental designs studied at the MnROAD facility.
Site evaluation report outlining results of On-Board Sound Intensity, RoboTex Texture, CTM Texture, DFT Friction testing equipment on various cells at MnROAD.
The testing was conducted in cooperation with Mn/DOT, including Bernard Izevbekhai with the Office of Materials and Maureen Jensen with the Materials and Road Research Program, among others. Mn/ROAD is a unique test facility which consists of dozens of test cells designed and constructed to evaluate pavement performance under environmental and traffic loading. Among these test cells are numerous concrete surfaces, including new surfaces recently constructed using different variants of diamond grinding. Other surfaces tested include turf drag and transverse tined textures.
This brief details that analysis for the mainline IRI data and discusses the development of MnDOT's IRI specifications and the use of MnROAD test sections to calibrate IRI test equipment.
One of the more difficult aspects of a pavement system for the engineer to study is the system’s response to moisture. Along with the dynamic (load response) sensors installed
during the construction of MnROAD, engineers at MnROAD also installed a variety of sensors to monitor the environmental effects that the pavement systems experience.
Furthermore, MnROAD engineers conduct a variety of environmental measurements to monitor the test pavements. After ten years of operation, MnROAD engineers have collected a long history of data for analysis. Furthermore, thanks to the reconstruction of some test cells, MnROAD engineers have been able to develop full-scale experiments to test various hypotheses about pavement drainage. This brief will detail some analysis and experiments using MnROAD data and/or the MnROAD facility.
