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This report highlights an investigation into concrete pavement performance problems caused by transverse joint misalignment on a segment of westbound Interstate 94 near Fergus Falls, Minnesota. In 1986, heavy rain during construction resulted in transverse joint locations based on estimated sawing guide marks. The results of dowel bar alignment, faulting, and load transfer efficiency measurements all demonstrate that misaligned transverse joints in relationship to the dowel bar assemblies contributed to early faulting that a minimum dowel bar embedment length of 64 mm (2.5 in.) is needed to prevent significant faulting and maintain reasonable load transfer efficiency across a joint. However, construction alignment tolerances and long-term concrete stress reduction near the dowels warrant the use of embedment lengths longer than 64 mm (2.5 in.). Since several of the joints investigated can be considered undoweled, accelerated faulting of these joints can be expected.

This report focuses on the first extensive forensic excavation of a paved test cell at the Minnesota Road Research Project (Mn/ROAD). A trench was dug in Cell 28 of the Low Volume Loop at Mn/ROAD to investigate a localized failure of the roadway. This report documents the trenching process and serves as a historical record of the in situ conditions of Cell 28 in the early summer of 1997. Data collected during this forensic excavation has contributed to the conclusion that mechanistic pavement design methods should include a maximum allowable stress criteria for aggregate base and subgrade. In addition, minimum hot-mix asphalt pavement thicknesses are required to prevent failures of aggregate base and subgrade. The tests performed during the investigation, as well as the analysis of available data, are discussed. The conclusions of the forensic research team as to the historical performance and subsequent deterioration of Cell 28 also are included.

The Dynamic Cone Penetrometer (DCP) is a test device used for measuring the strength and variability oh unbound layers of soil and granular material. The DCP is not a new test device, but transportation organizations in Canada and the United Stales, including the Strategic Highway Research Program (SHRP), have shown a renewed interest in its unique capability of measuring a profile of in situ foundation characteristics. A desire to more fully characterize subsurface conditions on the Minnesota Road Research Project (Mn/ROAD) led to the initial use of DCP by Mn/DOT. From an operational perspective it is very attractive because the DCP is both portable and simple to use. The objective of this research was to explore ways that IXP's could effectively be used by Minnesota pavement and materials engineers and to perform the testing, analysis, and learning necessary for establishing relationships between DCF' test results and other commonly used foundation parameters. This paper describes the design and operation of the DCP as well as an overview of the theoretical basis for use of the device. In addition, correlation results, data profiles, case histories and related information are presented.

The introduction of fiber reinforced plastic (FRP) dowels as possible alternatives to the epoxy-coated and stainless-steel dowels, was contemporaneous with a paucity of knowledge of their long-term performance. Although various isolated efforts had examined them on a short-term basis and produced some qualitative results or long-term predictive models, actual long-term performance in service was still unknown and unanalyzed. An experiment at the MnROAD Research facility placed FRP dowels in 2000 in some of the jointed plain concrete pavement (JPCP) panels of test Cell 52 and used epoxy-coated dowels in the remaining panels of this cell. The contiguity of this test cell with Cell 53, a JPCP high-performance concrete cell built in 2008 with stainless steel dowels, and Cell 54, a taconite JPCP cell with epoxy-coated dowels in built in 2004, facilitated a comparative analysis of performance of the 3 dowel types particularly in load transfer efficiency (LTE) and ride quality. The difference in the inception of the cells constrained a performance over time and encouraged a time-series autoregressive integrated moving average (ARIMA) analysis. Projections to 30 years showed that LTE and ride quality of FRP dowels were no different from those of the epoxy-coated dowels and the stainless-steel dowels although Cell 53 was designed and built with thicker concrete (12-in. thick) compared to 7.5-in in cells 52 and 54.

The success of in-car devices that aid drivers depends in part on driver reaction and acceptance. This project looks at the human factors considerations for the GENESIS Program, which studies the use of personal communication devices to deliver real-time traffic and transit information services. Researchers used vehicle simulation to learn more about the impact of the use of GENESIS devices. The report includes a discussion of human factors issues for consideration during the operational test evaluation phase and recommends suggestions to improve in-car computer screens and for future simulation studies.

An extensive pavement material sampling and testing program was devised and carried out during construction of the Minnesota Road Research Project (Mn/ROAD). This guide provides comprehensive information regarding the type and location of soil and base material samples collected from the Mn/ROAD project. Information regarding nondestructive soil testing is provided which includes Dynamic Cone Penetrometer (DCP) and Falling Weight Deflectometer (FWD) testing. Material sample information provided is divided into sample types, then into proposed research applications. Sample locations and proposed laboratory tests are shown. Testing locations for the nondestructive tests conducted on the project are provided. Information listed in a "Mn/ROAD ID#" column provides a unique identification to each sample. This sample identification can be used to request samples or obtain test result data contained in the Mn/ROAD database. During construction of the Mn/ROAD project, approximately one third of the samples collected were immediately tested to characterize the subgrade layers of the project. The remaining samples were put into storage for future research needs. Appendices A, B and C contain descriptions of Mn/ROAD database tables related to soil samples and nondestructive tests. Test cell profile diagrams are provided in Appendix D.

The research shows that highway speed horn antenna ground penetrating radar equipment and automated analysis software can accurately measure asphalt thickness. To accurately measure concrete and base thickness, lower speed ground coupled equipment also must be used. In the project, researchers collected radar data for pavement layer thickness at the 40 Mn/ROAD research pavement sections to obtain accurate as-built pavement layer thickness data on the sections. A blind comparison between radar asphalt thickness data and available cores shows an R-square of 0.98. For concrete thickness, the R-square was 0.76. The report details results for base and subbase thickness and for the layer thicknesses of the four aggregate sections.

A committee consisting of Minnesota Department of Transportation (Mn/DOT) Bridge, Pavement, and Geotechnical personnel was formed to examine the present and propose a future comprehensive Non-Destructive Testing (NDT) Program. The overall intent of their study was to define the scope of Mn/DOT's NDT program focusing on the Offices of Construction and Materials Engineering, Minnesota Road Research, and Bridge, with the intent of providing basis for future investment and use of NDT methods. Several NDT devices are currently being used by the Department. They have a great potential for saving the Department time and money, and will enable the employees to perform their jobs better and more efficiently. Other NDT devices are still being investigated for their potential benefits to the Department, and have not been fully evaluated. Though these devices may ultimately save time and money and improve performance, many are labor intensive. Staff approval must be obtained before making large financial or personnel commitments. It is recommended that each of the three areas have someone in charge of the evaluation of all new equipment and methods.

This report presents the development of simulation software for modelling dynamically loaded pavement response. The analysis is carried out by employing the finite element method and by integrating the resulting discrete equations of motion through the central difference method. The lower pavement layers (base, subbase and subgrade) are assumed to be elasto-plastic and are described by using the flow theory of plasticity. The mapped infinite elements are used instead of viscous boundaries to mitigate the wave reflection from the boundaries of the model. The predicted pavement responses are compared with the experimental results obtained by a Falling-Weight Deflectometer (FWD). Dowel bar load transfer mechanism is also analyzed.

Asphalt mixture variations that result from moisture fluctuations in aggregate stockpiles pose a serious problem at dryer-drum plants. The moisture content of a stockpile is infrequently measured, if at all. If the proportion of aggregate is not adjusted to account for its moisture content, an improper mix will result. This project looked at identifying a practical and accurate field method or probe for measuring the moisture content of aggregates, testing the probe in a hot-mix plant, and developing a control strategy for asphalt oil addition to the mix. Researchers identified a suitable commercial probe by reviewing past research and conducting laboratory studies. Testing in the plant showed that this probe could rapidly measure aggregate moisture in plant conditions at the same level of accuracy as gravimetric measurements. Researchers also developed a control strategy for the asphalt oil addition. Testing showed the effectiveness of this control, in conjunction with commercial probe moisture measurements in the feed bin. A problem with probe operations robustness was identified.