Browsing by Subject "Electrical conductivity"

Now showing 1 - 3 of 3
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    Evaluating Roadway Subsurface Drainage Practices
    (Minnesota Department of Transportation, 2009-01) Canelon, Dario J.; Nieber, John L.
    This project involved the evaluation of some configurations of pavement subsurface drainage systems, including the conventional edgedrain system, and two centerline configurations, at 2-foot and 4-foot depths. Testing of these configurations took place on a newly constructed eight-mile section of Nobles County CSAH 35 near Worthington. Drained roadway sections were 500 feet long for each drainage treatment. Each of the treatments was replicated six times, with the outflow for each replication outlet through a tipping-bucket flow monitoring system. The experimental design tested both the drain configuration and the effect of relative elevation of the roadway. Measurement of relative wetness of the pavement base and subgrade materials for each of the drainage treatments was conducted with a Geonics electromagnetic induction instrument (EM38). Data were collected from March 2006 until November 2008, with breaks during the winter periods. Statistical analyses were conducted to look for treatment effects, using both drained volumes as well as the EM38 measurements as measures of drain efficacy. Additional project work included a finite element analysis of the drainage configurations, EM38 evaluation of drainage effectiveness of an open-graded base construction for streets in the city of Worthington, and evaluation of the potential drain plugging effect of crushed concrete fill.
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    Hydrogeologic Monitoring at University of Minnesota Outreach, Research and Educational Park (UMore Park), 2011
    (2012-01) Groten, Joel T.; Alexander, E. Calvin
    The mining of the gravel resource and subsequent development at the University of Minnesota Outreach, Research and Educational Park (UMore Park) may potentially impact the groundwater quality at, and around UMore Park. In order to provide a pre-mining baseline against which to monitor potential water quality changes, monitoring of water quality in selected monitoring wells began in 2009 (Anger and Alexander, 2010.) Anger and Alexander (2010) reviews the previous work defining the hydrogeology of the UMore Park site and installing the existing monitoring wells. This report updates and Anger and Alexander (2010) with monitoring data obtained through June 2011.
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    Innovative Materials and Advanced Technologies for a Sustainable Pavement Infrastructure
    (Minnesota Department of Transportation, 2021-06) Le, Jia-Liang; Marasteanu, Mihai; Zanko, Lawrence M.; Matias de Oliveira, Jhenyffer; Calhoon, Thomas; Turos, Mugurel; Stricherz, Tyler; Hopstock, David M.; Hegg, Vern
    It is widely acknowledged that early detection of material damage and timely rehabilitation can lead to a significant reduction in the life-cycle cost of asphalt pavements. This research investigates the capabilities of damage detection and healing of graphite nanoplatelet (GNP)-taconite modified asphalt materials. The first part of the research is concerned with the application of GNP-taconite modified asphalt materials for damage detection using electrical conductivity. It is shown that, as compared to conventional asphalt materials, the GNP-taconite modified asphalt materials exhibit an improved electrical conductivity due to the electron hopping mechanism. Based on the mathematical analogy between the elastostatic field and the electrostatic field, a theoretical model is derived to relate the change of electrical conductivity to the damage extent of the material. Although, in principle, the material damage can be accessed using the electrical conductivity, the practical application of this method is complicated by the fact that the conductivity is influenced by the moisture content. The second part of the research investigates the damage healing capability of GNP-taconite modified asphalt materials heated by microwave. GNP-taconite modified asphalt materials can effectively absorb the heat generated by the microwave, and the rising temperature can effectively heal the microcracks in the binder. This damage-healing mechanism is verified by a set of semi-circular beam tests. Finally, microwave heating technology is applied to the tack coat system. It is shown that, with microwave heating, the GNP-taconite modified asphalt material can effectively improve the bond strength of the interface of the tack coat system.