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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=PHNlYXJjaD48cGFyYW1zPjxwYXJhbSBuYW1lPSJzdWJqZWN0bG9naWMiIHZhbHVlPSJvciIgLz48cGFyYW0gbmFtZT0idGVybXNsb2dpYyIgdmFsdWU9Im9yIiAvPjxwYXJhbSBuYW1lPSJsb2NhdGlvbiIgdmFsdWU9IjAiIC8+PC9wYXJhbXM+PGZpbHRlcnM+PGZpbHRlciBmaWVsZD0ia2V5d29yZHMiIHZhbHVlPSImcXVvdDtGYXRpZ3VlJnF1b3Q7IGFuZCAmcXVvdDtsaWZlJnF1b3Q7IGFuZCAmcXVvdDtwcmVkaWN0aW9uJnF1b3Q7IGFuZCAmcXVvdDthc3BoYWx0JnF1b3Q7IGFuZCAmcXVvdDtwYXZlbWVudHMuJnF1b3Q7IGFuZCAmcXVvdDtQYXJ0JnF1b3Q7IiBvcmlnaW5hbF92YWx1ZT0iRmF0aWd1ZSBsaWZlIHByZWRpY3Rpb24gaW4gYXNwaGFsdCBwYXZlbWVudHMuIFBhcnQgMSIgLz48L2ZpbHRlcnM+PHJhbmdlcyAvPjxzb3J0cz48c29ydCBmaWVsZD0icHVibGlzaGVkIiBvcmRlcj0iZGVzYyIgLz48L3NvcnRzPjxwZXJzaXN0cz48cGVyc2lzdCBuYW1lPSJyYW5nZXR5cGUiIHZhbHVlPSJwdWJsaXNoZWRkYXRlIiAvPjwvcGVyc2lzdHM+PC9zZWFyY2g+" 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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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Development of Pavement Structural Analysis Tool (PSAT) for Iowa Local Roads</title>
      <link>https://trid.trb.org/View/2196869</link>
      <description><![CDATA[Iowa has three classes of public roads: state primary highways, county (secondary) roads, and city streets. Among these, Iowa county roads serve rural Iowa transport needs by assuring a public road connection (i.e., to local access roads) for serving as conduits that channel the flow of people and commodities to and from towns and terminals (i.e., farm-to-market roads). Many Iowa county pavement systems are multilayered structures that have experienced multiple cycles of construction and renewal that make it more complex to estimate pavement structures’ current structural capacities. This study developed a Microsoft Excel macro and Visual Basic for Applications (VBA)-based automated Pavement Structural Analysis Tool (PSAT) with three analyzing options—asphalt concrete (AC) pavement systems with 1 to 10 layers on a (1) stabilized base, (2) granular base, and (3) stabilized base and granular base—to estimate the current structural capacities of in-service pavement systems by following consecutive sections within the user-friendly platform. To address this aim, a systematic approach to develop a highly realistic annotated synthetic database was created for use in artificial neural network (ANN)-based pavement response prediction models that required inputs of pavement materials and structural features and outputs of pavement responses, deflections, and strains at critical locations within the pavement structure. In addition, the equivalent layer theory (ELT) concept was integrated into the PSAT to simplify multilayered pavement systems into three-layered systems—an asphalt layer, a base layer, and a subgrade layer. Thus, it could make it easier for an Iowa county engineer to understand the current structural capacities of in-service county pavements. Mechanistic- and empirical-based approaches were also integrated into the tool to estimate the remaining service life (RSL) associated with two types of major failures for flexible pavements, namely fatigue and rutting failures, by relating pavement responses predicted by the ANN models through transfer functions. The PSAT is expected to be used as part of routine pavement analysis, design, and asset management practices for better prioritization and allocation of resources, as well as to support effective communication related to pavement needs both with the public and with elected officials.]]></description>
      <pubDate>Fri, 23 Jun 2023 13:45:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2196869</guid>
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    <item>
      <title>Presentation of Predictive Models for Two-objective Optimization of Moisture and Fatigue Damages Caused by Deicers in Asphalt Mixtures</title>
      <link>https://trid.trb.org/View/2130922</link>
      <description><![CDATA[The best way to deal with the freezing of the road surfaces is to use deicers, especially in cold areas. The presence of moisture causes various stresses in the pavement and reduces the strength of mixtures. Using anti-stripping agents can decrease the moisture sensitivity of asphalt mixtures. Researchers have evaluated the impact of different deicers on the moisture sensitivity of asphalt mixtures. However, fewer studies have been conducted on the effect of these materials on fatigue failure and thermodynamic parameters of asphalt mixtures. Moreover, fewer studies have been performed to find the exact optimum amount of additives for maximizing the two objectives of tensile strength ratio (TSR) and fatigue life ratio (NFR) concurrently in moisture and fatigue damages. So in this research, the moisture sensitivity and fatigue failure of asphalt mixtures under the influence of different deicers, including calcium magnesium acetate (CMA), potassium acetate (PA), and sodium chloride (NaCl), were investigated using nanohydrated lime (NHL) as an anti-stripping agent. The surface free energy (SFE) of materials and the permeability of asphalt mixtures were examined, and a boiling water test was applied. Finally, the prediction models of multivariate regression (MVR), group method of data handling (GMDH), and genetic programming (GP) were provided to obtain optimum additive percentage with two objectives of TSR and NFR. The results showed that GP had a higher R-value than the 2 other methods such that the R-value of GP for TSR and NFR was 98.8 % and 99.8 %, respectively. The optimization results showed that 1.17 %, 1.34 %, 0.87 %, 1.21 %, and 1.06 % NHL, respectively, were the best optimum values to maximize the TSR and NFR simultaneously in all samples and samples saturated in water, CMA, NaCl, and PA solutions.]]></description>
      <pubDate>Tue, 23 May 2023 10:12:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2130922</guid>
    </item>
    <item>
      <title>Characteristics and Prediction of Fatigue Resistance between Asphalt Pavement Layers Based on Shear Stiffness Decay Rate</title>
      <link>https://trid.trb.org/View/1946555</link>
      <description><![CDATA[The evaluation of fatigue performance between asphalt pavement layers highly depends on fatigue life and shear stiffness. However, fatigue life and shear stiffness are comprehensive evaluation indexes. In the study of the formation mechanism and decay process of fatigue resistance, both of them cannot provide effective theoretical support. In this study, the shear stiffness decay curve was obtained through a four-point shear fatigue test under different loading conditions. The initial shear stiffness and the shear stiffness decay rate of interlayers were chosen to evaluate the initial resistance and process resistance. The effects of temperature, loading frequency, compressive stress, and shear stress on the evolution of interlayer fatigue performance were investigated. The findings of this study revealed that first, with the increase of the compressive stress perpendicular to the interlayer interface, the interlayer shear stiffness decay curve transitions from a cubic curve type to a quadratic curve type and gradually changes to a linear equation. Second, the ranking of influence degree of four factors on initial resistance and process resistance was obtained, and the influence mechanism analysis was carried out based on the variance analysis result. Finally, a multiple nonlinear regression model was established successfully to predict the fatigue life and to explain the internal connection between the initial shear stiffness, shear stiffness decay rate, and fatigue life.]]></description>
      <pubDate>Fri, 24 Jun 2022 17:07:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1946555</guid>
    </item>
    <item>
      <title>Uppföljning av provväg E6 med polymermodifierade bundna lager : Uddevalla</title>
      <link>https://trid.trb.org/View/1948889</link>
      <description><![CDATA[The test road Geddeknippel–Kalsås was built in 2003–2006 as a part of the E6 motorway north of Uddevalla in both south and north directions. Test sections were constructed with polymer-modified bitumen (PMB) consisting of several variants of SBS (styrene-butadiene-styrene) and EVA (Ethylene-vinyl acetate). The test sections have been planned by the Swedish Transport Administration in collaboration with industry. The purpose is to clarify the benefit of using the PMB in asphalt mixtures in asphalt concrete layers of flexible pavements.  Long-term-pavement-performance was carried out through laboratory tests of samples and follow-up measurements. Evaluation of the pavement’s sections and prognoses of deterioration development at the test sections has been carried out with various models and test methods. The results showed that the asphalt concretes with and without PMB aged over time, however, to varying degrees. Hardening of asphalt concrete due to aging affects the development of pavement conditions and this must be considered for correct assessment of degradation of the sections. It was found that the PMBs used in this work can significantly affect the function of asphalt concretes. The choice of a PMB must be planned considering the desired functional characteristics and the asphalt concrete layer position in a road structure. Different PMB variants may be needed for different purposes. For example, different PMBs may be needed against rutting alternative fatigue cracking and sometimes the conventional asphalt concrete may be most optimal considering pavement life and from a socioeconomic aspect.  Rutting model PEDRO has been found to be a practical tool for clarifying the impact of the most important parameters on rut growth in bitumen-bound layers. It describes the proportion of rut depth from each asphalt layer and in respect of the layer’s functional properties and position in the road structure for an optimal choice of asphalt materials. The Swedish Transport Administration's investment in counting traffic volume through WIM (Weight-in-motion) measurements is superior to the current method based on estimation of the traffic volume from AADT (Average Annual daily traffic) in prediction of in-situ life. However, so far there are very limited WIM measurements.]]></description>
      <pubDate>Fri, 06 May 2022 17:07:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/1948889</guid>
    </item>
    <item>
      <title>Analysis of the Effects of Voids in Mineral Aggregate on Pavement Fatigue Performance Using AASHTOWare Pavement ME Design and FlexPAVE</title>
      <link>https://trid.trb.org/View/1882974</link>
      <description><![CDATA[Deviation of volumetric properties of asphalt mixtures, such as voids in mineral aggregates (VMA), from the agency–specified thresholds can cause minor to significant changes in pavement performance. This paper presents the results of the study on the effects of the deficiency of VMA parameters (?VMADesign) on the fatigue performance of asphalt pavements. Dynamic modulus and fatigue tests were performed on two types of mixtures (one with 9.5-mm nominal maximum aggregate size (NMAS) and the second one with 19-mm NMAS) at three levels of ?VMADesign. The results were analyzed using two simulation models (i.e., FlexPAVE 1.1Alpha and AASHTOWare Pavement ME Design version 2.3.0 (Pavement ME)). The results showed that fatigue service life reduction was linearly correlated to an increase in ?VMADesign and could reach almost 50 % for a pavement with ?VMADesign of 3 %. Additionally, while both Pavement ME and FlexPAVE showed comparable results in terms of top-down cracking/damage predictions, the results of the analysis performed by FlexPAVE in terms of bottom-up damage prediction were more consistent with respect to the expected behavior of pavement structure in terms of damage.]]></description>
      <pubDate>Fri, 12 Nov 2021 17:23:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1882974</guid>
    </item>
    <item>
      <title>Ermüdung, plastische Verformung und Temperatur im Spaltzug-Schwellversuch und dessen Auswirkung auf Dimensionierung und Prognose der Nutzungsdauer von Asphalttragschichten</title>
      <link>https://trid.trb.org/View/1669491</link>
      <description><![CDATA[Mit dem Spaltzug-Schwellversuch kann gemäß den "Technischen Prüfvorschriften für Asphalt" (TP Asphalt-StB), Teil 24, die Ermüdungsfunktion von Asphaltgemischen im Labor ermittelt werden, um diese im Rahmen der rechnerischen Dimensionierung gemäß den "Richtlinien für die rechnerische Dimensionierung von Verkehrsflächen mit Asphaltdeckschicht" (RDO Asphalt 09) zur Schichtdickenfestlegung beziehungsweise Nutzungsdauerberechnung verwenden zu können. Die TP Asphalt-StB geben für die versuchstechnische Bestimmung der Ermüdungsfunktion mithilfe der Spaltzug-Schwellversuche einen Prüftemperaturbereich von -15 bis +20 Grad Celsius vor. Es wird jedoch empfohlen, die Spaltzug-Schwellversuche bei einer Prüftemperatur von +20 Grad Celsius durchzuführen. Grund für die Temperaturbegrenzung auf max. +20 Grad Celsius ist, dass bei allen Versuchen mit schwellender Belastung zusätzlich zur Materialermüdung auch plastische Verformungen auftreten. Diese plastischen Verformungen, die in zunehmendem Maße in Abhängigkeit vom Belastungsniveau bei höheren Temperaturen auftreten, sollen auf ein solches Maß begrenzt werden, dass während der Ermüdungsversuche vorwiegend elastische Verformungen in Probekörpern entstehen. Anhand von Versuchsergebnissen wird in der Veröffentlichung gezeigt, inwieweit das Erreichen des Makrorisskriteriums bei Prüftemperaturen von +20 Grad Celsius vorwiegend durch Ermüdung beziehungsweise vorwiegend durch plastische Verformungen hervorgerufen wird und welche Konsequenzen sich daraus für die rechnerische Dimensionierung von Asphaltbefestigungen ableiten lassen. (A) ABSTRACT IN ENGLISH: The fatigue curves for asphalt mixes can be determined using the results of Cyclic Indirect Tensile Tests (CITT) according to TP Asphalt-StB Part 24 [1]. These fatigue curves are required for the mechanistic empirical design procedure of pavements according to RDO Asphalt 09 [4]. The test procedure for the determination of the fatigue curves specifies a temperature range between -15 and +20 degree centigrade. However, it is recommended that the indirect tensile tests for the asphalt mixes be carried out at a  temperature of +20 degree centigrade. The reason for the maximum temperature limitation of +20 degree centigrade is that in all tests when a swelling load is applied on the sample, plastic  deformation occurs in addition to fatigue. These plastic deformations, which increasingly occur as a function of the stress level at higher temperatures, should be limited  to such an extent that during the fatigue tests predominantly elastic deformations occur in the specimen. On the basis of the laboratory test results, the paper  demonstrates the extent to which the macro-crack criterion at test temperatures of +20 degree centigrade is achieved mainly due to fatigue instead of plastic deformation, along with  presenting outcomes which can be derived for implementation into mechanistic-empirical design procedure of asphalt pavements.]]></description>
      <pubDate>Tue, 16 Mar 2021 11:04:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/1669491</guid>
    </item>
    <item>
      <title>Exploring indicators for fatigue cracking in hot mix asphalt pavements using simplified-viscoelastic continuum damage theory</title>
      <link>https://trid.trb.org/View/1502763</link>
      <description><![CDATA[Fatigue cracking in asphalt pavements results in decreased ride quality, decreased fuel economy, and provides an avenue for intrusion of water. Since the current asphalt mixture design relies primarily on proportioning of component materials, performance is not considered directly. An advancement in technology is to design through direct material property assessment and correlations to field performance, a performance-based mixture design. The objectives of this paper are to: (1) relate mixture stiffness, fatigue, and pavement system characteristics together for use in the performance-based mixture design; (2) identify a Simplified-Viscoelastic Continuum Damage (S-VECD) model output parameter which produces the most separation between poorly and satisfactorily performing structures when combined with dynamic modulus and phase angle information; and (3) evaluate the impact of reclaimed asphalt pavement on the performance of the indicator. A pavement response model was coupled with the S-VECD analysis to determine the fatigue life using a representative pavement structure. Results show a relationship exists between the fatigue life of the pavement system, the dynamic modulus and phase angle, as well as an energy-based index. This approach holds promise because of its reliance on material attributes that can be derived on one testing machine. The model parameters from dynamic modulus and direct tension cyclic fatigue testing can also be incorporated into performance prediction software, further enhancing the appeal of a performance specification using the approach described in this study.]]></description>
      <pubDate>Fri, 16 Mar 2018 09:51:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1502763</guid>
    </item>
    <item>
      <title>Field Measurement and Modeling of Vertical and Longitudinal Strains from Falling Weight Deflectometer Testing</title>
      <link>https://trid.trb.org/View/1492872</link>
      <description><![CDATA[This study investigates longitudinal tensile and vertical compressive strains at the bottom of the hot mix asphalt (HMA) layer subjected to a falling weight deflectometer during different seasons at the fully instrumented Integrated Road Research Facility located in Edmonton, Alberta, Canada. First, dynamic strain pulses were measured and characterized with respect to their shapes and durations. Also, the impact of the HMA layer temperature in different seasons on the in situ measured strains was evaluated, and strong relationships between peak strain values and temperature were found. Second, some well-established analysis packages were used to predict the measured responses based on the backcalculated and laboratory-determined moduli. Finally, by using the bottom-up fatigue cracking and rut depth prediction models, the impact of strain prediction error on the estimated performance was also evaluated. Through comparison of predicted and measured strains, it was found that on average the potential fatigue life can be overestimated by 1.7 times, whereas the potential rut depth of HMA is less affected, overestimated by 1.2 times based on the three software programs used.]]></description>
      <pubDate>Wed, 24 Jan 2018 09:20:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1492872</guid>
    </item>
    <item>
      <title>Asphalt Stiffness and Fatigue Parameters from Fast Falling Weight Deflectometer Tests</title>
      <link>https://trid.trb.org/View/1438530</link>
      <description><![CDATA[With the occurrence of the Falling Weight Deflectometer (FWD) in the 1980’s it became possible to quickly determine the most important input parameters for the ‘mechanistic’ part of the mechanistic-empirical (M-E) pavement design method—the in-situ modulus and critical stress/strains in pavement. However, the ‘empirical’ part which predicts the future pavement deterioration is still primarily based on costly and extensive full scale Accelerated Pavement Testing (APT). Therefore, engineers have had to mainly rely on small-scale laboratory test methods for evaluation of existing pavement structures or a particular pavement design. Given the limitations of the laboratory test methods, there is a wide gap between the critical response and prediction of the future pavement deterioration or “residual life”. To bridge this gap, the Fast Falling Weight Deflectometer (FastFWD)—an electrically powered FWD with faster loading rates—was evaluated to assess its suitability to rapidly predict the fatigue performance of asphalt pavements. In this experiment, the FastFWD was used to apply 700,000 load applications on a pavement test section over 8 days, later supplemented by additional loads up to over 1.6 million load cycles. The dynamic modulus master curve was first backcalculated from in-situ FastFWD testing and was used to filter out the viscoelastic response of the asphalt layer due to temperature changes from the damage of the material due to repeated loading. An Incremental-Recursive fatigue model accurately predicted the damage in asphalt modulus. With the FastFWD it is now possible to perform in-situ performance testing of pavements to provide input parameter for the ‘empirical’ part of the M-E methods.]]></description>
      <pubDate>Wed, 01 Feb 2017 13:16:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/1438530</guid>
    </item>
    <item>
      <title>Pavement Management, Volume 2</title>
      <link>https://trid.trb.org/View/1401548</link>
      <description><![CDATA[This issue contains fifteen papers on pavement management.  The papers have been categorized into four parts.  The first part concerns full-scale accelerated pavement testing and includes two papers on asphalt rubber binders and moduli of full-depth reclamation materials. The second part concerns rigid pavement design and contains four papers.  Specific topics addressed in this section include a state design procedure, a life-cycle cost-based decision framework for failed pavement materials, transverse crack development, and calibration of performance models.  The third part concerns flexible pavement design and contains six papers.  Specific topics addressed in this section include system dynamics and porous friction courses, climate data for mechanistic-empirical pavement performance prediction, field transverse cracking, asphalt mixture creep compliance, fatigue analysis, and aggregate base layer properties.   The fifth part concerns pavement rehabilitation and includes three papers.  These papers address full-depth reclamation, load transfer behavior for bonded concrete overlays, and an in-place pavement recycling project.]]></description>
      <pubDate>Mon, 21 Mar 2016 10:18:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/1401548</guid>
    </item>
    <item>
      <title>Fatigue life prediction in asphalt pavements, part 1</title>
      <link>https://trid.trb.org/View/1177623</link>
      <description><![CDATA[]]></description>
      <pubDate>Fri, 24 Aug 2012 01:34:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1177623</guid>
    </item>
    <item>
      <title>Development of a Flexible Pavement Database for Local Calibration of the MEPDG, Part 2 Evaluation of ODOT SMA Mixtures</title>
      <link>https://trid.trb.org/View/1117042</link>
      <description><![CDATA[There has been some reluctance on the part of some in Oklahoma to use SMA mixtures. There are several factors that could be involved in the slow acceptance of SMA mixtures in Oklahoma. These factors are 1) the extra expense associated with the higher binder contents and better quality aggregates required, 2) a lack of data indicating that SMA mixtures perform substantially better than conventional Superpave mixtures and 3) a lack guidance on thickness design benefits, including appropriate input parameters for the MEPDG. The objectives this study are to evaluate the performance of SMA mixes compared to S-4 mixes and to determine the performance benefits. Testing included Hamburg Rut Tests and dynamic modulus testing. Hamburg rut testing indicated that SMA resists permanent deformation better than ODOT S-4 mixes made with the same source and grade of asphalt cement. Both measured and predicted dynamic modulus of SMA was less than ODOT S-4 mixes. The Asphalt Institutes fatigue equation indicated longer fatigue life for SMA compared to S-4 mixes. MEPDG prediction models contradict these findings.]]></description>
      <pubDate>Wed, 19 Oct 2011 12:53:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1117042</guid>
    </item>
    <item>
      <title>The prediction of fatigue life of asphalt mixtures using four-point bending tests</title>
      <link>https://trid.trb.org/View/1096856</link>
      <description><![CDATA[Fatigue resistance is used in the analysis and design of pavements to predict their life cycle.  The results of fatigue tests are expressed in terms of the number of cycles for the tensile strain level applied.  Two constants take part in this relationship.  To know these two constants, at least two fatigue tests are needed, performed at different strain levels to obtain those constants.  However, based on laboratory results analysis, the constants can be correlated and, in this case, the relationship between the fatigue life and the strain level has only one constant, which can be evaluated using the results obtained by a fatigue test.  This paper presents the evaluation of the relationship for Portuguese mixtures based on the results obtained from more than 50 different asphalt mixtures and the prediction of only one of those constants with fatigue test results.  The paper also presents an analysis of the fatigue life using fatigue laws with only one constant. (a) For the covering entry of this conference, please see ITRD abstract no. E220164.]]></description>
      <pubDate>Tue, 15 Mar 2011 10:56:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1096856</guid>
    </item>
    <item>
      <title>Heat Reflectivity Properties of Asphalt Mixtures Modified with Nano A/SBS-II: Prediction of Temperature in Asphalt Pavement</title>
      <link>https://trid.trb.org/View/1090456</link>
      <description><![CDATA[Test results of heat reflectivity for asphalt that is modified with nano A/SBS are given by the authors in part I, and are used directly to predict the temperature in asphalt pavement. Firstly, the heat reflectivity is defined by using the temperature increment between the stable value between the modified asphalt and the base asphalt. Then, a two-dimensional finite element model is developed to model a common multilayered pavement and a reflective multilayered pavement under various environmental conditions. Meteorological data, such as air temperature, solar radiation and wind speed etc., are obtained from Ningbo weather stations. Finally, the distribution of temperature in both the reflective pavement and the common asphalt pavement is calculated and compared. It is indicated that the temperature in the reflective asphalt pavement is lower than that of the common asphalt pavement. As a result, the temperature fatigue of the asphalt pavement can be lowered and thus the pavement’s life prolonged.]]></description>
      <pubDate>Wed, 16 Feb 2011 13:42:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1090456</guid>
    </item>
    <item>
      <title>Fatigue Performance Prediction of North Carolina Mixtures Using the Simplified Viscoelastic Continuum Damage Model</title>
      <link>https://trid.trb.org/View/1086607</link>
      <description><![CDATA[Fatigue performance modeling is a major topic in the field of asphalt concrete modeling work. Currently, the only standard fatigue test available for asphalt concrete mixtures is the flexural bending fatigue test, AASHTO T-321. Several issues are associated with flexural fatigue testing, the most important being that the stress state is not uniform but varies with the depth of the specimen, and that the beam specimen fabrication equipment is not widely available. Viscoelastic continuum damage (VECD) fatigue testing is a promising alternative to flexural fatigue testing. Different researchers have successfully applied the VECD model to asphalt concrete mixtures using constant crosshead rate direct tension tests. However, due to the load level limitation of the newly released Asphalt Mixture Performance Tester (AMPT) testing equipment, there is an immediate need to develop a model that can characterize fatigue performance quickly using cyclic test data. In this study, a simplified VECD model, developed at North Carolina State University, is applied to various North Carolina mixtures that are part of the NCDOT project, Local Calibration of the MEPDG for Flexible Pavement Design. A failure criterion that is based on pseudo stiffness is developed from the test data. The application of the VECD model using this failure criterion results in very good agreement between the measured and predicted fatigue life for the eleven mixtures. In addition, a completely independent verification study is conducted for the FHWA ALF mixtures, including both unmodified and modified mixtures. Again, it is found that the simplified VECD model predicts the fatigue life of the ALF mixtures well. It is shown that the simplified VECD model based on the data from a single temperature and a single strain level can predict fatigue test results fairly accurately under various temperature conditions and at various strain levels. It is also shown that the model can be utilized further to simulate both controlled strain and controlled stress direct tension fatigue testing and gain insight into the impact of various mixture design variables, such as asphalt content, binder grade, NMAS, and the inclusion of RAP materials, on the fatigue performance.]]></description>
      <pubDate>Thu, 20 Jan 2011 11:22:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1086607</guid>
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