1,720,966 research outputs found
Recycled Asphalt Pavement (RAP) Effects on Binder and Mixture Quality
No full textThis report looks at how Recycled Asphalt Pavement (RAP) has been used in Minnesota for over 25 years. The most commonly used method is to mill material from an existing pavement and incorporate it into a new asphalt mix. Previous experience and specifications allow various RAP percentages depending on the traffic level. Past research has also shown the effects of RAP on both the high- and low-temperature properties of asphalt cement and the asphalt mixtures. Therefore, it becomes an important priority to study and determine the effects various types and percentages of RAP have on the asphalt cement and mixture quality. This will result in a rational design for asphalt mixture that contain RAP and could change Mn/DOT's asphalt specification.Local Road Research BoardLi, Xinjun; Clyne, Timothy R.; Marasteanu, Mihai O.. (2004). Recycled Asphalt Pavement (RAP) Effects on Binder and Mixture Quality. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/1140
Evaluation of Asphalt Binders Used for Emulsions
No full textThis project was an effort to better characterize asphalt emulsions that are typically used in cold in-place recycling (CIR) applications. A simple approach was presented that treated the cured residue as asphalt binder and applied the standard Superpave specifications to the material. A literature review examined methods that have historically been used to produce, characterize, and apply asphalt emulsions. Four emulsions were tested in this project: CRS-2P, CSS-1, EE, and HFMS-2P. The emulsions were cured two ways, the first being allowed to sit overnight in a pan at room temperature, and the second being a modified RTFOT approach. Air cured samples were also aged in the PAV. These residues were then tested with the BBR and DT at low temperatures and with the DSR at high and intermediate temperatures. AASHTO MP1 specifications were applied in order to characterize the emulsions by PG grade. Following this, AASHTO MP1a specifications were followed in order to find the critical cracking temperature of the emulsions. Master curves were constructed from the DSR tests of complex shear modulus vs. frequency. Finally, a sample mix design was presented using these emulsions and an empirical equation to predict the dynamic modulus of the mixture.Local Road Research BoardMarasteanu, Mihai O.; Clyne, Timothy R.; Basu, Arindam. (2003). Evaluation of Asphalt Binders Used for Emulsions. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/913
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Preliminary Laboratory Investigation of Enzyme Solutions as a Soil Stabilizer
No full textThis research studied the effect of two enzymes as soil stabilizers on two soil types to determine how and under what conditions they function. Researchers evaluated the chemical composition, mode of action, resilient modulus, and shear strength to determine the effects of the enzymes A and B on the soils I and II. The enzymes produced a high concentration of protein and observations suggest the enzymes behave like a surfactant, which effects its stabilization performance. The specimens were subjected to testing of varying lengths of time to determine their performance. Researchers observed an increase in the resilient modulus as the curing time increased but that an increase in application rate, as suggested by manufacturers, did not improve the performance of the enzymes. The study also suggests noticeable differences between the two enzymes and their effects on the soils in terms of resilient modulus and the stiffness of the soil.Local Road Research BoardMarasteanu, Mihai O.; Hozalski, Raymond M.; Clyne, Timothy R.; Velasquez, Raul. (2005). Preliminary Laboratory Investigation of Enzyme Solutions as a Soil Stabilizer. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/991
Best Practices for the Design and Construction of Low Volume Roads - REVISED
No full textThis 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.Local Road Research BoardSkok, Eugene L.; Timm, David H.; Brown, Marcus; Clyne, Timothy R.; Johnson, Eddie N.. (2003). Best Practices for the Design and Construction of Low Volume Roads - REVISED. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/798
Dynamic and Resilient Modulus of Mn/DOT Asphalt Mixtures
No full textThis 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.Minnesota Department of TransportationMarasteanu, Mihai O.; Clyne, Timothy R.; Li, Xinjun; Skok, Eugene L.. (2003). Dynamic and Resilient Modulus of Mn/DOT Asphalt Mixtures. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/897
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Low Temperature Cracking of Asphalt Concrete Pavement
No full textThis report investigates the low temperature behavior of asphalt pavements based on experimental results obtained for three mixtures used in the construction of cells 33, 34, and 35 at Mn/ROAD facility as well as field information acquired over the years at Mn/ROAD. As a result of this research, a new test method was developed to determine the low temperature fracture properties of asphalt mixtures based on tests performed on semi-circular specimens tested in bending. This method can be used to select materials with better fracture resistance and therefore better performance in the field. Two models were developed to predict the low temperature cracking performance of asphalt pavements. The first model predicts the crack spacing in asphalt pavements exposed to low temperatures based on continuum mechanics and the frictional restraint provided by the aggregate base. The second model predicts the accumulation of damage and the propagation of the crack through the asphalt layer as temperature drops based on cohesive zone model.Local Road Research BoardMarasteanu, Mihai O.; Li, Xue; Clyne, Timothy R.; Voller, Vaughan; Timm, David H.; Newcomb, Dave. (2004). Low Temperature Cracking of Asphalt Concrete Pavement. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/792
Investigation of the Low-Temperature Fracture Properties of Three MnROAD Asphalt Mixtures
No full textIn this research effort, field cores were taken from cells 33, 34 and 35 at the MnROAD facility to determine the fracture properties of the field mixtures, to compare them with the laboratory-prepared mixtures analyzed in a previous study, and to evaluate the effect of aging at different depths in the asphalt layer. In addition, the properties of the recovered binders from the field cores as well as the properties of the original binders aged in laboratory conditions were investigated. The test results and the analyses performed indicate that the fracture tests performed on asphalt binders and asphalt mixtures have the potential to predict the field performance of asphalt pavements with respect to thermal cracking. The binder results confirm the predictions of the current performance grading system; however, it appears that the fracture resistance of the PG-34 asphalt mixture is better than the fracture resistance of the PG-40 mixtures, which is the opposite of what the PG system predicts.Local Road Research BoardLi, Xinjun; Zofka, Adam; Li, Xue; Marasteanu, Mihai; Clyne, Timothy R.. (2006). Investigation of the Low-Temperature Fracture Properties of Three MnROAD Asphalt Mixtures. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/608
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