Browsing by Subject "Moisture content"

Now showing 1 - 3 of 3
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    Crack and Concrete Deck Sealant Performance
    (Minnesota Department of Transportation, 2009-03) Johnson, Karl; Schultz, Arturo E.; French, Catherine; Reneson, Jacob
    The objective of this project is to define the current state-of-the-art regarding the use of bridge deck sealants and crack sealers to extend the life of reinforced concrete bridge decks. The report includes the information generated from a literature review and survey which focused on current and significant studies in the field of deck and crack sealing. The intent of the survey was to determine common practices for the use and application of these sealers in different States throughout the United States. Based on the information collected from the literature review and the survey, the best sealant materials and application practices are recommended for use in Minnesota and throughout the Midwest. The report consists of four sections including: (1) a synthesis of the literature review on the background, application, and performance of concrete deck sealants and crack sealers; (2) a summary of the survey conducted by Mn/DOT to determine the current selection criteria, materials, application practices, and findings from different states in United States; (3) an assessment of selection criteria, materials, application practices, and performance; and (4) conclusions, recommendations and areas in need of further research.
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    On-Line Measurement of Moisture Content of Iron Ore Slurries
    (2013) Gao, Feng; Davis, Richard A
    This report presents a method of measuring moisture content in iron ore slurries using the application of microwave. The composition of iron ore slurries consists of magnetite, hematite, calcium carbonate, magnesium carbonate, siderite, alumina, silica, and water. When being placed in an electromagnetic field, interactions will happen between the slurry components and the field. Permittivity is the main parameter to describe these interactions. Since water has the largest dielectric constant compared with other materials, the water content of the material can be estimated from measured permittivity values. For each species, attenuation and microwave phase shift are two intermediate functions related to permittivity, temperature and bed depth when a microwave is passing through particles on conveyor belt. According to theory, a linear model is expected between the materials’ moisture content and the ratio of attenuation and phase shift.
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    Performance-Based Measurement of Optimum Moisture for Soil Compaction
    (Minnesota Department of Transportation, 2013-11) Hansen, Bradley J.; Nieber, John L.
    Part of the challenge achieving maximum field density in subgrade materials is transferring the optimal compaction and moisture content data from laboratory testing to the field. This research investigated the proficiency of four different instruments at accurately predicting moisture contents of three subgrade soils (loam, silt, silty/clay) commonly used in Minnesota roadway construction projects. The four instruments were; DOT600 (moisture content), WP4C dewpoint potentiometer (matric suction), the Button Heat Pulse Sensor (BHPS) (temperature rise vs. moisture content), and an exudation pressure test device. The DOT600 showed a strong correlation between the output period (measured in micro-seconds) and volumetric water content. The WP4C did not accurately measure matric suction for any of the loam, silt or silt/clay soils at suctions below 250 kPa. Published data shows that the matric suction of soils compacted at optimum moisture content is usually in the range of 200 – 300 kPa. The BHPS showed a strong correlation between measured temperature rise and water content but in its current configuration is not rigorous enough to withstand field conditions. The exudation pressure device was applied to soils compacted in a AASHTO T99 mold at various moisture contents. Water was exuded from the packed samples at pressures between 100 and 500 psi corresponding to AASHTO-T99 moisture contents of 10 to 25 %. Accurate moisture content readings from any of these instruments may not be as important as a more precise and simple calibration between the measurement units of the instrument and the optimum moisture content determined from the AASHTO T99 test.