Browsing by Author "Skok, Eugene L"
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Item Asphalt Pavement Analyzer (APA) Evaluation(2002-09-01) Skok, Eugene L; Johnson, Eddie N; Turk, AmirThis report considers the Asphalt Pavement Analyzer (APA) as a tool for evaluating the rutting susceptibility of Minnesota Hot Mix Asphalt (HMA). Its authors analyze the 25 responses to a questionnaire sent to members of the APA Users' Group and conduct a literature review. Based on this evidence, they recommend that Mn/DOT purchase an APA. The tool provides a measure of rutting susceptibility; is reasonably reliable and repeatable; and has been used by over 60 agencies and contractors. In addition, procedures for conducting tests are available in ASTM and AASHTO formats and the Users' Group provides a forum for discussion and support. Keywords-asphalt pavement analyzer, hot mix asphalt, rutting, ESALsItem Best Practices for the Design and Construction of Low Volume Roads - REVISED(2003-11-01) Skok, Eugene L; Timm, David H; Brown, Marcus; Clyne, Timothy R; Johnson, Eddie NThis report presents information about the use of the mechanistic-empirical procedure (MnPAVE) in designing hot-mix asphalt pavements in Minnesota. Researchers developed the MnPAVE software program using information from the Minnesota Road Research Project (Mn/ROAD) test facility and from 40-year-old test sections around Minnesota. MnPAVE procedures use Equivalent Standard Axle Loads (ESALs) to evaluate traffic loading, and the report includes methods to estimate these values for design purposes over a 20-year design life, as well as a procedure to measure vehicle type distributions. In addition, the report presents an evaluation of subgrade soils for each thickness design procedure, summarizes Minnesota Department of Transportation specifications that relate to embankment soil construction and to construction of the pavement section materials, and recommends specific density or quality compaction using a control strip. It also includes best practices on setting up projects most effectively to follow specifications.Item Dynamic and Resilient Modulus of Mn/DOT Asphalt Mixtures(2003-01-01) Marasteanu, Mihai O; Clyne, Timothy R; Li, Xinjun; Skok, Eugene LThis report presents the results of laboratory testing to determine the complex modulus and phase angle of asphalt mixtures. Laboratory tests were performed on four different asphalt mixtures from the Mn/ROAD site. Testing was performed at six temperatures and five frequencies. Data from the tests were processed through a nonlinear regression curve fit to genereate master curves of dynamic modulus and hpase angle vs. frequency. These master curves were compared to results obtained from Witczak's predictive equations. It was found, as expected, that the dynamic modulus increased with an increase in frequency and a decrease in temperature. The model used to fit dynamic modulus master curves provided a good fit for the experimental data. The modulus values calculated using the 2000 predictive equation fit the test data reasonably well for Cell 21 and 35 mixtures, but the differences for Cells 33 and 34 were more significant. Smooth master curves for phase angle could not be obtained. An exploratory study to use a vibration exciter to measure dynamic modulus proved unsuccessful. This study was done under the framework of NCHRP Projects 1-37A, 9-19, and 9-29 that recommends dynamic modulus both as a design parameter and a simple performance test. Keywords-complex dynamic modulus, asphalt mixtures, phase angle, master curve.Item Special Practices for Design and Construction of Subgrades in Poor, Wet, and/or Saturated Soil Conditions(2003-05-01) Skok, Eugene L; Johnson, Eddie N; Brown, MarcusHighway embankment construction progresses vertically in stages, beginning with the subgrade. For a variety of reasons, it is desirable to use naturally occurring soils for subgrade material. In some cases this is not possible due to poor soil conditions; in order to avoid realignment it is necessary to improve the subgrade material. A literature review provides background for special construction methods to be used for subgrade soil enhancement. Additonal information about modification, stabilization, reinforcement, and substitution methods and material was gathered from a questionnaire directed to Minnesota state, county, and city highway engineers. Based on questionnaire responses, a series of highway agency interviews were conducted to provide more detailed information about the enhancement methods. Enhancement selection recommendations and special practice methods for construction were developed from the agency interviews, questionnaire responses, and literature review.