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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <title>Components of Variability in Bituminous Concrete Pavement Construction. Volume 2: Field and Laboratory Evaluation</title>
      <link>https://trid.trb.org/View/2680595</link>
      <description><![CDATA[The objectives of phase-II of the project were: 1) to determine the components of the total variability in the measured quality attributes of acceptable bituminous concrete pavement construction in Oklahoma, 2) to assess the Oklahoma Department of Transportation's (ODOT's) specification tolerances for bituminous concrete pavement construction, 3) to evaluate the accuracy of the nuclear density gauge, and 4) to correlate the results of the nuclear test method for asphalt content determination with those obtained using the solvent extraction method. To meet these objectives, a research plan consisting of literature review, statistical experimental design, field sampling, and laboratory testing was adopted. Random sampling was conducted both at the production plant and the roadway independent of acceptance and job control sampling. Testing was performed in the materials laboratories of the different ODOT Divisions. ANOVA results indicated that sampling and testing variances represent a significant portion of the total observed variance in the measured quality attributes of bituminous concrete pavement construction. The computed percentages within QA/QC specification tolerances indicated that the present tolerances are practical and defensible. Correlations between density measurements obtained from the nuclear gauge and core samples ranged from 0.49 to 0.84. The use of calibrated relationships through regression analysis improved the estimation of core densities from nuclear measurements. Variability due to sampling and testing was larger in the core method than the nuclear gauge method. The correlation coefficient between individual asphalt content measurements using the extraction method and the nuclear gauge method was 0.63. No significant difference was found between the average asphalt content obtained from the extraction method and the average asphalt content obtained using the nuclear gauge method. Testing variability was less with the nuclear gauge method than the solvent extraction method.]]></description>
      <pubDate>Sat, 04 Apr 2026 17:15:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2680595</guid>
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    <item>
      <title>Evaluation of Correlations between Intelligent Compaction Measurement Values and In Situ Spot Measurements</title>
      <link>https://trid.trb.org/View/1688494</link>
      <description><![CDATA[Compaction is one of the most important operations in pavement construction. Poor compaction of base and sub-base can lead to various types of deterioration/failure, and consequently increase the cost of maintenance and rehabilitation. Non-uniformity and inconsistency of the compaction are the most prevalent problems associated with conventional compaction techniques. The density-based quality control (QC) and quality assurance (QA) practices for compaction evaluation (spot test measurements) only cover less than 1% of the compacted area. Therefore, there is a need for transitioning from a point-wise to system-wide inspection practices. Intelligent compaction (IC) is an innovative technology that can improve the uniformity and consistency of compaction and provide a system-wide stiffness-based inspection practice. The main objective of this study was to evaluate correlations between intelligent compaction measurement values and in situ spot test measurements. To this end, spot measurements were taken during IC operation in a reclaimed base project in Route 117, Vermont, and simple linear regression models were built to investigate the correlation between intelligent compaction measurement values (CMVs) and dynamic cone penetration index (DCPI)/nuclear gauge density (NGD)/pavement quality indicator (PQI)/core densities. The results indicated that the correlation between the CMVs and spot measurements was meaningful only in case of DCP tests performed during the initial reclaim phase. Different mechanisms for compaction quality measurement and variation of material properties throughout the project were the main reasons for the observed weak correlation.]]></description>
      <pubDate>Mon, 30 Mar 2020 17:48:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1688494</guid>
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    <item>
      <title>Evaluation of Non-Destructive Density Determination for QA/QC Acceptance Testing</title>
      <link>https://trid.trb.org/View/1567458</link>
      <description><![CDATA[Density is often considered one of the most important parameters for long-term pavement performance. Proper density specifications require the contractor and the Louisiana Department of Transportation and Development (DOTD) to follow quality control (QC) and quality assurance (QA) procedures. Contractors often utilize the nuclear density gauge (NDG) as part of their QC processes to monitor density (and soil moisture) for earthwork and unbound layers; and to establish rolling patterns for asphalt pavement layers. DOTD QA procedures require determination of density utilizing NDG for earthwork and unbound layers; and roadway core densities for asphalt pavement layers. However, nuclear technology in the NDGs requires extensive certifications and handling procedures; and the coring process is a destructive testing process to a freshly paved asphalt mat. This research investigated the potential of low to non-nuclear devices with little to no radioactive footprint, to replace the NDG and roadway coring for asphalt and soils QA operations in Louisiana. The newly developed gauges are simple and easy to use and do not require extensive training, certifications, or lengthy paperwork; and are less destructive to the road. For this research, two separate field and lab evaluations took place: (1) Louisiana Transportation Research Center's (LTRC’s) Geotechnical group evaluated the final density procedures for soils and (2) LTRC’s Asphalt group evaluated the final density procedures for asphalt pavements. The study determined the NDG to be a better option for DOTD in soils QA processes; and the non-destructive testing (NDT) for asphalt, a.k.a. thin-lift nuclear density gauge (TLNDG) and non-nuclear density gauge (NNDG), to be viable options for asphalt QA processes. The low-nuclear density gauge (LNDG) exhibited limitations of depth requirements and service life. The TLNDG and NNDGs were shown to have good correlation to core density results. NDT was determined to be safer, faster, better for the longevity of the pavement, and more economical for both contractors and DOTD.]]></description>
      <pubDate>Tue, 20 Nov 2018 17:00:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/1567458</guid>
    </item>
    <item>
      <title>WisDOT Asphaltic Mixture New Specifications Implementation – Field Compaction and Density</title>
      <link>https://trid.trb.org/View/1459021</link>
      <description><![CDATA[The main research objectives of this study were to evaluate hot mix asphalt (HMA) Longitudinal Joint type, method and compaction data to produce specification recommendations that will ensure the highest density longitudinal joint, as well as evaluate and produce a specification for Thin Layer Overlay HMA that will ensure proper and consistent compaction throughout the pavement. In 2014, longitudinal nuclear density data were collected throughout Wisconsin on 28 projects. In 2015 three projects were visited (for more extensive data collection) with varying longitudinal joint type: vertical, notched wedge, milled and safety edge. Additionally one thin lift overlay project was visited. Each 2015 project consisted of nuclear density readings, core density, NCAT Asphalt Permeameter and Hamburg Wheel testing. Results showed that a nuclear density gauge, specifically when used in the parallel position (relative to traffic and paving direction), is an acceptable tool to use to determine in place densities. However, a nuclear / core correlation on a test strip is recommended for all projects. The standard nuclear gauge overestimates density, while the thin lift nuclear gauge underestimates density. The milled longitudinal joint achieved the highest density, followed by notched wedge and safety edge. Vertical longitudinal joints had the lowest average joint densities. Heating joints resulted in higher densities for all joint types where data were available. Rolling pattern included both contractor standard practice and Federal Highway Administration (FHWA) recommended methods but was not found to have significant influence on longitudinal joint density.]]></description>
      <pubDate>Sat, 15 Apr 2017 18:46:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1459021</guid>
    </item>
    <item>
      <title>Evaluation of the Troxler model 4640 thin lift nuclear density gauge</title>
      <link>https://trid.trb.org/View/1172986</link>
      <description><![CDATA[This report describes the results of a research study to determine the effectiveness of the Troxler Model 4640 Thin Lift Nuclear Density Gauge. The densities obtained from cores and the nuclear density gauge from seven construction projects were compared.  The projects were either newly constructed or under construction when the tests were performed.  A linear regression technique was used to investigate how well the core densities could be predicted from nuclear densities.  Correlation coefficients were determined to indicate the degree of correlation between the core and nuclear densities. Using a statistical analysis technique, the range of the mean difference between core and nuclear measurements was established for specified confidence levels for each project.  Analysis of the data indicated that the accuracy of this gauge is material dependent.  While relatively acceptable results were obtained with limestone mixtures, the gauge did not perform satisfactorily with mixtures containing siliceous aggregate.]]></description>
      <pubDate>Thu, 23 Aug 2012 22:58:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1172986</guid>
    </item>
    <item>
      <title>Comparison of HMA Pavement Core Density Test Methods for Use in Establishing Density Gauge Correlation Factors</title>
      <link>https://trid.trb.org/View/1093273</link>
      <description><![CDATA[The Oregon Department of Transportation allows use of nuclear density gauges for determining in-place density of hot mix asphalt, but correlation of measurements to pavement core densities is not necessarily required.  Correlations are typically used to resolve discrepancies between quality control and quality assurance test results and are used only for the lift in question.  New correlations are performed on new lifts only when the gauges continue to show a difference. The agency is considering a requirement to correlate nuclear gauges to pavement cores for all paving projects incorporating dense-graded HMA, but first would like to know if correlation factors established for one lift of pavement on a particular project can be used for the other lifts on the same project. 	The paper summarizes analyses comparing correlation factors derived from combinations of density measurements obtained from nuclear and electromagnetic gauges and three core test methods.  Principal findings indicate all nuclear gauges need to be correlated to core densities to ensure accurate results, electromagnetic gauges are less likely to require correlations, and correlation factors established for the first pavement lift can be used on other lifts under certain constraints.]]></description>
      <pubDate>Mon, 28 Mar 2011 07:45:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/1093273</guid>
    </item>
    <item>
      <title>Density Measurement Verification for Hot Mix Asphalt Concrete Pavement Construction</title>
      <link>https://trid.trb.org/View/924646</link>
      <description><![CDATA[Oregon Department of Transportation (ODOT) requires a minimum density for the construction of dense-graded hot mix asphalt concrete (HMAC) pavements to ensure the likelihood that the pavement will not experience distresses that reduce the expected service life of the pavement. Currently, the ODOT Standard Specifications call for density measurements for both quality control and quality assurance testing to be made using nuclear density gauges that are calibrated using reference blocks. Hence, acceptance (i.e., purchase) of the HMAC pavement (or portions thereof) relies on the accuracy of the measurements. However, it has been observed that density measurement results using nuclear gauges have been questionable on a number of projects and that repeatability and reproducibility with the same gauge and between gauges have also been unattainable. Further, these observations have called into question the confidence placed in the use of nuclear gauges for determining HMAC pavement density. The overall objective of the project was to recommend a system that accurately quantifies density of dense-graded HMAC pavements. This involved critically evaluating how ODOT currently measures HMAC density, investigating and evaluating what other agencies do to measure HMAC density, and conducting testing and analysis of alternate ways of measuring HMAC density (e.g., by measuring the density of cores). Statistical analyses comparing nuclear gauge measurements to core densities provided convincing evidence that correlation of nuclear gauge measurements to core densities is necessary to ensure accurate results from nuclear gauges. Analyses comparing correlation factors across lifts of pavements constructed under three differing construction scenarios provided strong evidence to suggest correlation factors established for one lift can be used on other lifts under certain constraints. Correlations are recommended for all gauges on each lift and whenever a new mix design is introduced. ODOT should implement use of the CoreLok device for measuring densities of pavement cores and laboratory-prepared specimens as well as further investigate the use of electromagnetic gauges for in-place HMAC density measurement.]]></description>
      <pubDate>Tue, 27 Jul 2010 19:15:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/924646</guid>
    </item>
    <item>
      <title>Correlation of Nuclear Density Readings with Cores Cut from Compacted Roadways</title>
      <link>https://trid.trb.org/View/788441</link>
      <description><![CDATA[A field procedure for use of the nuclear density gauge was developed that resulted in nuclear gauge density data closely resembling in-place density obtained from cores. Procedural recommendations intended to improve its accuracy were made. The nuclear gauge data were collected on seven sites during Connecticut Department of Transportation pavement construction projects in 2003 and 2004. The findings indicate that the six individual nuclear gauge density units used for this study do not produce similar results and do not consistently correlate with core densities. The differences between the core density values obtained by the three laboratories and the nuclear gauge readings were significantly higher than the 0.1% maximum theoretical density (MTD) reported accuracy currently used by Connecticut Department of Transportation (ConnDOT) for acceptance on projects. Significant variation was also found between the results of core density samples obtained by three different laboratories on the same samples. In addition, the variability of the nuclear density gauge error differed not only from gauge to gauge, but also from location to location and is present for both nuclear gauge density testing modes (backscatter versus thin lift). The effect of the nuclear gauge orientation during testing with respect to the new mat was statistically different but very small; the mean difference was 0.05% of MTD. When the nuclear gauge was in the longitudinal direction, the density reading was slightly higher than those taken in the transverse direction. The time recording interval for the nuclear gauge was found to be relatively significant with respect to minimizing the difference between the nuclear gauge densities and core densities. The longer the recording time interval for the nuclear density gauge, the smaller the difference between the core density values and nuclear gauge densities. If the nuclear gauge continues to be used for project Quality Assurance, it is recommended that the recording time interval be 1-minute and that the acceptance reported accuracy be set to 1% of MTD. A new project-by-project nuclear gauge density correction procedure that requires 10 cut cores to improve accuracy is presented in this report.]]></description>
      <pubDate>Mon, 11 Sep 2006 16:21:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/788441</guid>
    </item>
    <item>
      <title>EVALUATION OF NEW NONNUCLEAR PAVEMENT DENSITY GAUGES WITH DATA FROM FIELD PROJECTS</title>
      <link>https://trid.trb.org/View/731933</link>
      <description><![CDATA[The introduction of new devices to measure pavement density requires an evaluation method that is both accurate and fair. Evaluations are commonly done by taking a density measurement with the gauge and comparing this density to the density obtained from a core taken at the same location.  This approach must meet two requirements; first, enough cores must be taken at each location to make the comparisons meaningful, and second, evaluation of these devices must be done with as many projects in as many locations as possible to account for all materials used in pavement construction.  Unfortunately, given the difficulties in obtaining field cores, large numbers of cores that can be used for evaluations are not available from all projects.  Therefore, any evaluation of density gauges must balance rigor with practicality.  The correlation coefficient was selected to evaluate the new nonnuclear pavement density gauge. However, because only a limited number of cores are available at each site for development of the correlation coefficient, this parameter by itself cannot be used to evaluate the new gauge. Instead, results from side-by-side comparisons with the accepted nuclear density gauge were used to aid in the evaluation of the new density-measuring device.  It was concluded, on the basis of data from 76 projects in six different states, that the proposed nonnuclear density gauge must be further developed before it can be used to determine pavement density.  In its current form, the densities obtained with the device do not correlate with the measured densities to the same degree that the densities measured with existing devices do.  Use of this nonnuclear device will introduce more uncertainty in pavement density measurements than that which already exists.]]></description>
      <pubDate>Thu, 16 Jan 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/731933</guid>
    </item>
    <item>
      <title>NUCLEAR DENSITY READINGS AND CORE DENSITIES: A COMPARATIVE STUDY</title>
      <link>https://trid.trb.org/View/505895</link>
      <description><![CDATA[Presented are the findings of an investigation performed to identify possible correlations between nuclear density gauge readings and core density results.  The nuclear density data were collected on a Superpave section of I-95 in Brevard County, Florida.  Core samples also were obtained from this section for laboratory density determination.  Five gauge units [Troxler models 3401, 3440 (two units), 3450, and 4640] and three core density methods (Florida test method FM 1-T 166, ASTM D1188, and dimensional analysis) were considered.  The relationships among the core density results were analyzed, then an investigation of the correlation among the different gauges used in this study was evaluated.  Finally, the performance of each of the units with respect to the core density results was assessed.  The findings indicated that the five nuclear gauge density units did not always produce similar results and did not consistently correlate with the core densities.  In addition, the nuclear density testing variability differed not only from gauge to gauge but also from location to location within each gauge.]]></description>
      <pubDate>Thu, 26 Aug 1999 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/505895</guid>
    </item>
    <item>
      <title>PAVEMENT DENSITY MEASUREMENT COMPARATIVE ANALYSIS USING CORE AND NUCLEAR METHODS (WITH DISCUSSION)</title>
      <link>https://trid.trb.org/View/488039</link>
      <description><![CDATA[Core samples have been historically used by agencies and contractors as the reference standard for asphalt pavement density measurement.  However, the process of using cores for density evaluation has several disadvantages, such as a destructive and lengthy test procedure that requires several hours to complete.  Highway agencies and contractors are using nuclear density gauges to offset this shortcoming, but they have experienced differing results between core samples and nuclear readings, raising concern for using a nuclear density gauge to measure pavement density.  This paper presents a statistically-based approach that will help agencies and contractors better understand the relationship between core samples and nuclear gauges.  Several comparison test sites are randomly collected from fourteen asphalt paving construction projects to compare core sample densities and nuclear gauge readings.  A correlation equation is developed with core sample densities, nuclear readings, pavement thickness, and maximum specific gravity of the asphalt mixture.  The variation of a correction factor established between core samples and nuclear readings is analyzed.  A method is provided for determining the number of density readings required to achieve a precise estimate of the average pavement density.]]></description>
      <pubDate>Fri, 07 Aug 1998 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/488039</guid>
    </item>
    <item>
      <title>THIN LAYER NUCLEAR ASPHALT DENSITY METER INVESTIGATION</title>
      <link>https://trid.trb.org/View/413987</link>
      <description><![CDATA[Main Roads Western Australia traditionally used coring techniques to detere use of a Troxler 4640B thin layer nuclear density meter was investigated to deliver density results immediately after the laying process.  The project involved the investigation of calibration procedures and the correlation of densities derives from the various calibration equations to the densities of cores.  The factory calibration equation and a special calibration equation, developed on a standard density block, gave variable and at times poor agreement with densities obtained from core samples.  Special calibration equations developed on an 100 mm thick asphalt block and on a block closely resembling the pavement structure provided only minor improvement.  The use of linear regression equations to calculate densities from counts of the detector responding to radiation passing mainly through the upper horizon of the pavement was then investigated.  The densities calculated by these equations were in close agreement with the densities of cores cut from the upper 25.4 mm horizon.  (a) For the covering abstract of this conference see IRRD abstract no. 861222.]]></description>
      <pubDate>Fri, 23 Dec 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/413987</guid>
    </item>
    <item>
      <title>A REPORT ON DENSITY TESTING ON ASPHALTIC SURFACE COURSE IN ALBERTA</title>
      <link>https://trid.trb.org/View/104816</link>
      <description><![CDATA[DURING THE PAST FEW YEARS THE ALBERTA HIGHWAYS DEPARTMENT HAS SHIFTED FROM THE TIME HONORED HAMMER & CHISEL METHOD TO CORING IN ORDER TO OBTAIN SPECIMENS FOR DENSITY TESTING ON SURFACE COURSE PROJECTS. COMPARISONS HAVE BEEN MADE BETWEEN THE TWO METHODS, AND RESULTS CONFIRM THE SUPERIORITY OF THE CORING METHOD. THIS SUPERIORITY IS EVIDENT IN A NUMBER OF AREAS. SOME LABORATORY WORK HAS BEEN DONE ON INVESTIGATING THE USEFULNESS OF AN APPARATUS WHICH MEASURES AIR PERMEABILITY OF PAVEMENT MIXES. LITERATURE CONCERNING THE INSTRUMENT CLAIMS THAT THE CORRELATION BETWEEN DENSITY AND AIR PERMEABILITY ALLOWS THE MACHINE TO BE USED FOR DENSITY DETERMINATION. TO DATE THE INSTRUMENT'S USEFULNESS APPEARS LIMITED. THE MOST ECONOMICAL AND RELIABLE METHOD OF OBTAINING PAVEMENT DENSITIES IS WITH THE USE OF CORING MACHINES. OTHER METHODS USED OR INVESTIGATED HAVE DEFINITE DISADVANTAGES WHEN COMPARED TO THE CORING PROCEDURE. THE PRESENT AND FUTURE DEVELOPMENT OF NUCLEAR, NONDESTRUCTIVE METHODS MAY REPLACE THE CORING UNIT. ECONOMICS AND THE FACT THAT A VISUAL INSPECTION OF A CROSS-SECTION OF THE FINISHED PRODUCT CAN BE MADE MAKE CORING AT PRESENT THE MORE PREFERABLE. /CGRA/]]></description>
      <pubDate>Fri, 30 Sep 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/104816</guid>
    </item>
    <item>
      <title>EVALUATION OF NEW NUCLEAR DENSITY GAUGES ON ASPHALT CONCRETE. FINAL REPORT</title>
      <link>https://trid.trb.org/View/361509</link>
      <description><![CDATA[This report documents an evaluation of the state-of-the-art capabilities of nuclear density gauges to monitor the density of asphalt concrete.  In particular, providing immediate information on compaction by the use of roller-mounted gauges and measuring the densities of thin layers were addressed.  The study included three phases: literature search, laboratory tests, and field trials.  The first phase included a review of current literature on the theory and operating characteristics of commercially available equipment and a review of State highway agency procedures and specifications for monitoring asphalt concrete density.  The second phase included a series of laboratory tests to verify factory calibrations and to determine the depth sensitivity, chemical composition errors, and thin-lift capabilities of the various gauges under laboratory conditions.  The third phase consisted of five sets of field trials.  The laboratory and field trials were carried out using five commercially available static gauges, two commercially available roller-mounted gauges, and one prototype roller-mounted gauge previously developed for the FHWA.  Full-depth measurements were taken at one field site and thin-lift measurements were taken at two sites.  At a fourth site, the three roller gauges were mounted on a compacting roller and used during paving operation.  At a fifth site, an attempt was made to correlate surface roughness and the speed of the roller-mounted gauges with density measurement accuracy. The density measurement data and the correlation of these data with core data are presented.  Laboratory results were accurate and precise.  In the field, results ranged from excellent to fair.  The inability to precisely field calibrate the gauges prior to each use hampered their performance.  The data show that, within limitations, static nuclear gauges can be used for acceptance testing of thin-lifts, but only when all parameters affecting the measurements are precisely known.  The dynamic gauges can be effectively used to monitor relative density growth.]]></description>
      <pubDate>Fri, 31 Jan 1992 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/361509</guid>
    </item>
    <item>
      <title>EVALUATION OF THE TROXLER MODEL 4640 THIN LIFT NUCLEAR DENSITY GAUGE. INTERIM REPORT</title>
      <link>https://trid.trb.org/View/357077</link>
      <description><![CDATA[This report describes the results of a research study to determine the effectiveness of the Troxler Model 4640 Thin Lift Nuclear Density Gauge.  The densities obtained from cores and the nuclear density gauge from seven construction projects were compared.  The projects were either newly constructed or under construction when the tests were performed.  A linear regression technique was used to investigate how well the core densities could be predicted from nuclear densities.  Correlation coefficients were determined to indicate the degree of correlation between the core and nuclear densities.  Using a statistical analysis technique, the range of the mean difference between core and nuclear measurements was established for specified confidence levels for each project.  Analysis of the data indicated that the accuracy of this gauge is material dependent.  While relatively acceptable results were obtained with limestone mixtures, the gauge did not perform satisfactorily with mixtures containing siliceous aggregate.]]></description>
      <pubDate>Thu, 31 Oct 1991 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/357077</guid>
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