The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
E R Brown - One of the best experts on this subject based on the ideXlab platform.
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Limited Round Robin Asphalt Content Test Using Troxler Furnace
1999Co-Authors: R Mallick, E R BrownAbstract:The Asphalt Content by Ignition test can be used to determine the Asphalt Content of a hot mix Asphalt (HMA). This the, developed by the National Center for Asphalt Technology (NCAT), burns the Asphalt binder from a mix and thus allows the determination of the amount of Asphalt binder in the mix. Troxler, Incorporated is one company that has developed an ignition oven for this test. There was a need to determine the accuracy and precision of the test method using the Troxler furnace. A round robin study using the Thermolyne furnace had been previously conducted (NCAT Report No. 95-3). This work with the Troxler was performed in 1997. The objective of this study was to determine the accuracy and precision values for Asphalt Content determined by the ignition test with the Troxler furnace.
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DEVELOPMENT OF A METHOD FOR EARLY PREDICTION OF THE Asphalt Content OF HOT-MIX Asphalt BY IGNITION TEST
Transportation Research Record, 1999Co-Authors: Rajib B. Mallick, E R BrownAbstract:The ignition test, developed by the National Center for Asphalt Technology, has proved to be a fast, pollution-free, automated, and inexpensive method for determining the Asphalt Content of a hot-mix Asphalt (HMA) sample. The time required to perform this test is about 30 to 40 min, which is significantly less than the time required to perform a solvent extraction test procedure. However, having the ability to determine Asphalt Content in 10 to 15 min would allow the technician to identify any problem in mix production much earlier and thus save a significant amount of time and money. Presented are the results of a study carried out to develop a method for estimating the Asphalt Content of an HMA sample within 10 to 15 min after testing begins. The method consists of determining the prediction factor on the basis of test results from two samples and then predicting the Asphalt Content of additional samples on the basis of the prediction factor and the Asphalt Content loss at 10 to 15 min of test. Use of this method is expected to provide a good estimate of the measured Asphalt Content in less than half the test time. This shortcut method should be used for quality control only and should not be used for acceptance or rejection of the mixtures.
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Asphalt Content by ignition round robin study
1996Co-Authors: E R Brown, Stuart MagerAbstract:The National Center for Asphalt Technology (NCAT) has developed a test method to determine the Asphalt Content of hot mix Asphalt (HMA) mixtures by ignition. In the ignition method, a HMA sample is subjected to 538 degrees C (1000 degrees F) in a furnace to ignite and burn the Asphalt cement from the aggregate. The difference in weight of the sample before and after ignition is used to determine the Asphalt Content of the mixture. The aggregate recovered after ignition testing may then be used for gradation analysis. A round robin study was completed by NCAT to determine the accuracy and precision of the ignition method. This paper discusses the round robin test program and the accuracy and precision values determined for the measured Asphalt Content and gradation by the ignition method. Equipment for the procedure was provided along with laboratory prepared HMA samples to 12 participating laboratories throughout the U.S. Four replicates of four HMA mixtures containing different aggregate types, gradations and Asphalt Contents were provided for testing. The results of the round robin study show that the ignition method can accurately measure the Asphalt cement Content of HMA mixtures with greater precision than solvent extraction methods without significantly affecting the gradation of the aggregate.
Brian D. Prowell - One of the best experts on this subject based on the ideXlab platform.
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Refinement of the Hot-Mix Asphalt Ignition Method for High-Loss Aggregates
Transportation Research Record, 2005Co-Authors: Graham C Hurley, Brian D. ProwellAbstract:Four methodologies for determining the Asphalt Content of mixtures containing high-loss aggregates in the ignition furnace were evaluated: the standard method using the Thermolyne furnace (control), the Troxler NTO infrared furnace, the Ontario method, and a Tempyrox glasscleaning oven. Six aggregate sources with high ignition furnace aggregate corrections were obtained from around the country: four dolomites, a basalt, and a serpentine/chlorite. Calibration factors were determined for each method at optimum Asphalt Content. Additional samples were then tested at optimum plus 0.5% Asphalt Content, and the measured Asphalt Content was calculated by using the correction factor determined for that method and aggregate source. The Tempyrox Pyro-Clean furnace, commonly used for cleaning laboratory glassware, produced the lowest aggregate correction factors. The standard method and the Ontario method, both using the Thermolyne ignition furnace, produced the smallest bias or error in measured Asphalt Content. Th...
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evaluation of infrared ignition furnace for determination of Asphalt Content
Transportation Research Record, 2003Co-Authors: Graham C Hurley, Brian D. ProwellAbstract:The Troxler Model 4730 infrared ignition furnace was compared with a standard Thermolyne ignition furnace. Comparisons conducted with a single unit of each furnace type were based on the correction factor for aggregate loss during ignition, accuracy, and the variability of the measured Asphalt Content and aggregate degradation during ignition. Forty-eight samples representing two nominal maximum aggregate sizes (9.5 and 19.0 mm), four aggregate types (granite, crushed gravel, limestone, and dolomite), and two Asphalt Contents (optimum and optimum plus 0.5% Asphalt Content) were tested in each furnace. The results indicated that the correction factors for aggregate loss during ignition were significantly different for each type of furnace, thus requiring a separate calibration for each type of furnace. In practical terms, the differences for all but the 9.5-mm nominal maximum aggregate size (NMAS) limestone and both dolomite mixtures were less than 0.1%. The samples with the optimum plus 0.5% Asphalt Content were tested by using the calibration factors developed for a particular mix-furnace combination. The results were analyzed in terms of accuracy (bias) and variability (standard deviation). Neither the measured biases nor the standard deviations for the two types of furnaces were significantly different. The results obtained with four sieve sizes (NMAS and 4.75, 2.36, and 0.075 mm) were evaluated for aggregate breakdown. A comparison of the aggregate gradations recovered from both furnaces indicated no significant difference in the degree of aggregate degradation. A round-robin investigation should be conducted to confirm that the precision of the infrared furnace is similar to the precision of the standard furnace.
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Alternate Methods To Determine Asphalt Content
Transportation Research Record, 1998Co-Authors: Brian D. ProwellAbstract:A method was identified to determine Asphalt Content to replace chlorinated solvent extraction. Production of trichloroethane was banned on December 31, 1995, as part of the 1990 Clean Air Act Amendments. Initially, the study focused on evaluating the nuclear Asphalt Content gauge with Marshall plugs. During the course of the research, early data from the National Center for Asphalt Technology (NCAT) indicated that the ignition method was a promising alternative. Testing was conducted with three generations of ignition furnaces. Four aggregate types were evaluated with typical surface mix and base mix gradations found in Virginia. Samples for evaluation were produced at four Asphalt Contents for each mix design representing typical field variation around the optimum. Operator variance samples were tested nondestructively in the nuclear gauge and then destructively by solvent extraction and the ignition method. As a result of the research, a test method was developed using the ignition furnace with an inte...
Jo Sias Daniel - One of the best experts on this subject based on the ideXlab platform.
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long term performance of pavement with high recycled Asphalt Content case studies
Transportation Research Record, 2013Co-Authors: Evan D Anderson, Jo Sias DanielAbstract:This paper summarizes the findings of several case studies on the long-term performance of recycled Asphalt pavement (RAP). The goal of these studies was to provide the paving community with documentation on the long-term performance of roadway sections with a high amount of RAP compared with virgin sections on the basis of available information. Roadway sections that contained more than 20% RAP and that had been in place for at least 10 years were identified across the United States with the help of local agencies. The long-term performances of these various recycled sections were compared directly with mixtures made with similar virgin materials via measurements of distress criteria. These distress criteria included rutting, cracking, ride quality, and any overall performance rating that the local agencies used to evaluate their pavement sections. The virgin sections were placed in the same general location and time frame as the recycled sections. The sections with high RAP Content, on average, tended t...
Donald E Watson - One of the best experts on this subject based on the ideXlab platform.
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determining air voids Content of compacted stone matrix Asphalt mixtures
Transportation Research Record, 2004Co-Authors: Donald E WatsonAbstract:This study compared the difference in air voids, optimum Asphalt Content, and voids in mineral aggregate (VMA) by using the saturated surface dry (SSD) and CoreLok methods for determining bulk specific gravity of the compacted specimen. The critical air voids level at which stone matrix Asphalt (SMA) mixtures are considered to become permeable was also determined for the gradations used in this study. Some of the pertinent conclusions are as follows. (a) There is a significant difference between air voids Content measured by the SSD method and the CoreLok method, (b) The CoreLok method resulted in a higher optimum Asphalt Content and VMA than designs based on the SSD method. (c) The CoreLok method may have a system error that overestimated the air voids Content at zero to low air voids levels; therefore, a correction factor was suggested to apply to the CoreLok results if needed. (d) At a permeability threshold of 125 X 10-5 cm/s, the critical air voids Contents are 4.5%, 5.7%, and 7.8% by the SSD method ...
Borwen Tsai - One of the best experts on this subject based on the ideXlab platform.
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effects of Asphalt Content and air void Content on mix fatigue and stiffness
Transportation Research Record, 1996Co-Authors: John T Harvey, Borwen TsaiAbstract:The primary objective of most procedures for Asphalt concrete mix design is to find an Asphalt Content that minimizes the possibility of stability failure while providing adequate fatigue and other durability characteristics. To date, the consequences of Asphalt Content selection and construction compaction on fatigue performance and flexural stiffness have not been thoroughly investigated and documented with experimental data. The results of laboratory-controlled strain flexural beam testing, (i.e., fatigue life and flexural stiffness) for one aggregate and Asphalt cement combination, five Asphalt Contents, and three air void Contents are presented. The results clearly indicate the benefits of a lower air void Content on both fatigue life and initial stiffness. Increased Asphalt Content was found to increase fatigue life and reduce stiffness. Alternative models for predicting fatigue life and initial stiffness using Asphalt Content, air void Content, voids filled with bitumen, and the volume concentrations of Asphalt and aggregate were evaluated. Elastic-layer theory was used to simulate the effects of air void Content and Asphalt Content on the fatigue life of several example overlays using the models for stiffness and fatigue life from the laboratory testing. The simulations indicated an increase in predicted pavement fatigue life for lower air void Contents and higher Asphalt Contents. Example simulations of the effects of increased Asphalt Content and decreased air void Content at the bottom of thick overlays indicated a marked increase in predicted fatigue life. It was also concluded that stiffness should not be included in regression for fatigue life models for mix design unless there is a clear understanding of the effects of other variables in the model that correlate with both fatigue life and stiffness.
