<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
    </image>
    <item>
      <title>Variability of Ignition Furnace Correction Factors</title>
      <link>https://trid.trb.org/View/1467080</link>
      <description><![CDATA[AASHTO T 308, “Determining the Asphalt Binder Content of Hot Mix Asphalt (HMA) by the Ignition Method,” requires determination of asphalt and aggregate correction factors for asphalt mix designs for each ignition furnace used to test a design. In some cases, where there are numerous asphalt mix designs or numerous ignition furnaces testing a particular mix design, correction factors may be shared between ignition furnaces, though this practice is not strictly permitted by AASHTO T 308 without supporting evidence. The objectives of this research were to (1) determine the significant influences that affect the variability of asphalt and aggregate correction factors for ignition furnaces; (2) develop guidelines for the installation, operation, and maintenance of ignition furnaces to minimize the variability in correction factors between furnaces; and (3) develop and document a statistically valid correction factor verification procedure to identify and troubleshoot causes for non-comparing, statistically different, or biased results of AASHTO T 308. The research was conducted in three parts: (1) a study of the sensitivity of asphalt and aggregate correction factors to variation in experimental factors such as furnace type, test temperature, asphalt content, and sample mass; (2) a round-robin study to identify correction factor outliers and determine the contributory cause(s); and (3) troubleshooting of outliers from the round-robin study. The research found that the primary factors affecting asphalt and aggregate correction factors determined by AASHTO T 308 are furnace type and test temperature. Conducting the test at 800°F appears to substantially reduce the magnitude and standard deviation of the correction factors for asphalt mixtures that do not contain lime. Sharing correction factors among different ignition furnaces appears acceptable for low correction factor aggregates (0.1% or less) but is problematic for aggregates with correction factors of 1.0% or greater. The current precision estimates in AASHTO T 308 appear applicable only to mixtures with low correction factor aggregates. The key product of this research is a Proposed Standard Practice for Installation, Operation, and Maintenance of Ignition Furnaces (Appendix I). Development of a verification procedure to identify causes for non-comparing, statistically different, or biased test results from ignition furnaces was found to be premature and further research is planned.]]></description>
      <pubDate>Mon, 15 May 2017 15:25:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/1467080</guid>
    </item>
    <item>
      <title>Refinement of the Hot-Mix Asphalt Ignition Method for High-Loss Aggregates</title>
      <link>https://trid.trb.org/View/762234</link>
      <description><![CDATA[This study evaluated four methodologies for determining the asphalt content of mixtures containing high loss aggregates in the ignition furnace. The methodologies tested were the standard method using the Thermolyne furnace (control), the Troxler NTO Infrared furnace, the Ontario Method using the Thermolyne furnace and a Tempyrox glass cleaning oven. Six aggregate sources with high ignition furnace aggregate correction factors were obtained from around the country: four dolomites, a basalt, and a serpentinite/chlorite. Calibration factors were determined for each method at optimum asphalt content. Additional samples were then tested at optimum plus 0.5 percent asphalt content and the measured asphalt content calculated using the correction factor determined for that method/aggregate source. The Tempyrox Pyro-Clean oven, commonly used for cleaning laboratory glassware, produced the lowest aggregate correction factors. The correction factors are consistent with results from thermogravimetric analysis. The standard method and the Ontario method, both using the Thermolyne ignition furnace produced the smallest bias or error in measured asphalt content. The standard deviation of the corrected asphalt contents for these high loss sources was higher than the within-lab standard deviation reported for AASHTO T308. The only exception was the Alabama source using the standard method. The Ontario Method and Tempyrox Oven generally reduced the variability of asphalt content measurements for high loss aggregates. None of the methods evaluated statistically reduced aggregate breakdown on the NMAS and 4.75 mm sieves. The Ontario method significantly reduced, but did not eliminate aggregate breakdown on the 0.075 mm sieve. A gradation correction factor, developed from the same samples used to determine the correction factor for asphalt content, greatly reduced the measured biases, in most cases to less than 1 percent. The Ontario method is recommended for immediate implementation for determining the asphalt content by the ignition method for high loss aggregates. The method consists of using an altered end point of less than 1 gram change over three consecutive minutes and using the highest test temperature of 538, 480 or 450°C (1,100, 896, or 842°F) that produces a correction factor less than 1 percent. The current AASHTO procedure specifies a 0.01 percent change over three consecutive minutes at either 538 or 482° (1100 or 900 °F).]]></description>
      <pubDate>Wed, 19 Oct 2005 15:48:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/762234</guid>
    </item>
    <item>
      <title>Refinement of the Hot-Mix Asphalt Ignition Method for High-Loss Aggregates</title>
      <link>https://trid.trb.org/View/761574</link>
      <description><![CDATA[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 glass-cleaning 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. The standard deviation of the corrected asphalt contents for these high-loss sources was higher than the within-laboratory standard deviation reported for AASHTO T308. The only exception was the Alabama source using the standard method. The Ontario method and Tempyrox oven generally reduced the variability of asphalt content measurements for high-loss aggregates. None of the methods evaluated statistically reduced aggregate breakdown on the nominal maximum aggregate size and 4.75-mm sieves. The Ontario method significantly reduced, but did not eliminate, aggregate breakdown on the 0.075-mm sieve. The Ontario method is the best method for immediate implementation for determining the asphalt content by the ignition method for high-loss aggregates.]]></description>
      <pubDate>Mon, 10 Oct 2005 13:05:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/761574</guid>
    </item>
    <item>
      <title>EVALUATION OF INFRARED IGNITION FURNACE FOR DETERMINATION OF ASPHALT CONTENT</title>
      <link>https://trid.trb.org/View/687204</link>
      <description><![CDATA[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.]]></description>
      <pubDate>Fri, 09 Jan 2004 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/687204</guid>
    </item>
    <item>
      <title>EVALUATION OF THE EFFECT ON AGGREGATE PROPERTIES OF SAMPLES EXTRACTED USING THE IGNITION FURNACE</title>
      <link>https://trid.trb.org/View/672684</link>
      <description><![CDATA[The Superpave mix design system includes four consensus aggregate properties to ensure aggregate quality:  coarse aggregate angularity, flat and elongated particles, fine aggregate angularity, and sand equivalent.  In addition to determining these consensus aggregate properties, ascertaining aggregate gradations and specific gravities are also required to complete an optimal mix design.  A method of extracting the asphalt from recycled asphalt pavement (or from quality control/quality assurance samples) that would produce a clean aggregate sample for analysis was needed.  The Virginia Department of Transportation (VDOT) has used the ignition method for determining asphalt content and for the recovery of aggregates for gradation analysis since 1995.  This study evaluated the effect on aggregate properties of samples extracted using the ignition furnace.  For the purposes of the study, recycled asphalt pavement was artificially produced by mixing virgin aggregates with asphalt and aging the mixture prior to extraction in the ignition furnace.  Consensus aggregate properties, specific gravity tests, and gradation analysis were performed on three replicates each of the virgin and recovered aggregates.  Only the sand equivalent test and aggregate-specific gravities showed regular significant differences.  It was found that the specific gravity values measured for aggregates recovered using the ignition furnace were closer to the measured values for the virgin aggregates than the effect specific gravity method which has been traditionally used for estimating a bulk gravity for recycled asphalt pavement.  As a result of this study, recommendations were made to the VDOT to change testing requirements on recycled asphalt pavement.]]></description>
      <pubDate>Thu, 22 Feb 2001 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/672684</guid>
    </item>
    <item>
      <title>EFFECT OF LIME ON IGNITION FURNACE CALIBRATION</title>
      <link>https://trid.trb.org/View/668733</link>
      <description><![CDATA[This study investigated mix components, other than aggregate source, that were perceived to affect the ignition furnace mixture calibration.  Four sets of experiments with one aggregate were designed and run to evaluate the effects of the amounts of lime, sulfur, calcium carboxylates, and fines.  Five asphalt binders with different chemistries were evaluated.  Two binders had high and low sulfur contents, respectively; two other binders contained relatively high concentrations of carboxylates.  Various concentrations of hydrated lime (0 to 3% by weight) were added to mixtures and were found to have a significant effect on the ignition furnace correction factor for all five binders.  The magnitude of the effect was large enough to cause the quality control tests to fail the tolerances established by the Virginia Department of Transportation.  The lime appears to react with the sulfur dioxide formed from the combustion of organic sulfur to generate calcium sulfate.  The amount of sulfur present in the asphalt can significantly affect the ignition furnace correction factor.  Initial thoughts that calcium carboxylates are reacting with carbon dioxide to produce some form of calcium carbonate were not substantiated.  The influence of carboxylic acid groups, however, does come into effect in the presence of lime.  This suggests that lime reacts with the combustion gases to produce some form of carbonate. Basalt fines and portland cement did not have a significant effect on the ignition furnace correction factor.  Additional testing should be conducted to assess the effects of fines representing other aggregates, particularly carbonates.]]></description>
      <pubDate>Tue, 03 Oct 2000 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/668733</guid>
    </item>
  </channel>
</rss>