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    <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" />
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    <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>
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    <item>
      <title>Virgin Asphalt–Aged Asphalt Interface Diffusion Behavior: Molecular Dynamics Simulation and GPC Test Validation</title>
      <link>https://trid.trb.org/View/2625819</link>
      <description><![CDATA[Reclaimed asphalt pavements (RAP) with reutilizing aged binders is very topical given their economic benefits. In particular, hot central-plant recycled technology is commonly used nowadays. In the hot recycled mixtures, virgin asphalt gradually diffuses into the aged one during the mixing process. The interaction on the virgin asphalt–RAP interface is critical for the reclamation of aged binders. However, the aforementioned diffusion behavior in reclaimed mixtures is not well comprehended. This study performed molecular dynamics (MD) simulation of the virgin asphalt–RAP interface diffusion behavior. Based on a four-component separation test, the molecular models of asphalt with different aging degrees were constructed, and their feasibility was verified by assessing the thermodynamic properties. Multiple MD simulations were performed to evaluate the effects of reclaimed mixture’s manufacturing factors, including time, temperature, aging degree of aged binders, and mineral fillers content on the interfacial diffusion efficiency. The diffusion process of virgin asphalt was subdivided into three stages according to the molecular motion paths and system energy change. The impact of manufacturing factors on the diffusion rate of virgin binders was found to be significant, but their effect on the diffusion rate of asphalt mastic was found to be relatively weak. Gel permeation chromatography (GPC) was performed to evaluate the diffusion behavior of the virgin asphalt, which results were in good agreement with the simulated ones. The diffusion process of virgin asphalt was promoted by extending diffusion times and temperatures, and the optimal values varied with the aging degree of aged binders. As the mineral fillers content of asphalt increases, the effect of altering diffusion temperature on the blending efficiency is reduced.]]></description>
      <pubDate>Tue, 17 Mar 2026 09:48:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2625819</guid>
    </item>
    <item>
      <title>A novel gel permeation chromatography-based assessment methodology for aging condition of SBS modified asphalt in recycled asphalt pavement</title>
      <link>https://trid.trb.org/View/2208783</link>
      <description><![CDATA[As fossil energy sources gradually become depleted, the reclamation of recycled asphalt pavement (RAP) has received increasing attention. During the production process of recycled mixtures, the aging conditions of binders in RAP need to be measured prior to the mixing design process. The conventional method adopts chemical solvents, including trichloroethylene and toluene to extract and recovery binders in the RAP. And then measure the corresponding properties of RAP binders. However, the whole process is complicated and time-consuming, and the used chemical solvents are highly toxic and harmful to researcher’s health. Some scholars have proposed some methods to test the aging condition of asphalt binders in the RAP directly without extraction and recovery using the novel observation instruments. However, these methods are not suitable for modified asphalt. At present, modified asphalt has been often used in the road construction, especially for SBS modified asphalt. As such, the present study aims to introduce a novel approach to test the aging conditions of SBS modified binders in the mixtures avoiding the extraction and recovery process based on gel permeation chromatography (GPC). For this purpose, the molecular weight distribution as well as the physical properties of modified asphalt and binders in the mixtures at various aging degrees were first analyzed using GPC test. The polymer and asphaltene content of asphalt binders derived from GPC test were found correlation well with the aging degrees and properties of asphalt binders. Following this, several estimation models correlating the polymer and asphaltene content with penetration, viscosity and rutting factor were established. The robustness of established models were verified using laboratory-aged asphalt mixtures with three different SBS modifier contents and two kinds of on-site RAPs. The verification results showed that the properties in the mixture were reasonably estimated.]]></description>
      <pubDate>Mon, 28 Aug 2023 09:34:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2208783</guid>
    </item>
    <item>
      <title>Investigation of the Changes in Asphalt Rubber Binder Fractions and Their Relation to Performance Enhancement</title>
      <link>https://trid.trb.org/View/2132036</link>
      <description><![CDATA[The relation between the molecular attributes of crumb rubber–modified asphalt (CRMA) fractions and the enhancement in the CRMA in-service properties was investigated. This was achieved by investigating the relation between the enhancement of the CRMA physical properties expressed in terms of its stiffness (complex modulus [G*]) and elasticity (phase angle [δ]) and the change in its molecular structure. Gel permeation chromatography analysis on the liquid phase of CRMA fractions was employed to characterize the change in the CRMA fractions (saturates, asphaltenes, naphthene aromatics, and polar aromatics). Research results showed that, for most of the samples, there is a marked difference in the weight average molecular weight and polydispersity index in relation to enhancement of the physical properties. This indicates that the crumb rubber–modified components played a role in the change of the internal structure of the CRMA, leading to enhancement in its physical properties and thus its expected in-service performance.]]></description>
      <pubDate>Tue, 28 Mar 2023 09:56:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2132036</guid>
    </item>
    <item>
      <title>Evaluating the storage stability of SBR-modified asphalt binder containing polyphosphoric acid (PPA)</title>
      <link>https://trid.trb.org/View/1976990</link>
      <description><![CDATA[The poor storage stability of polymer-modified asphalt (PMA) binder hinders its applications. Traditionally, the softening point test is utilized to evaluate the storage stability, which shows less sensitivity compared with the rheological test. This study attempts to evaluate the effects of polyphosphoric acid (PPA) contents on the storage stability of SBR-modified asphalt binder from empirical, rheological, and molecular aspects. Specifically, the softening point and multiple stress creep recovery (MSCR) test were adopted to assess the phase separation of SBR&PPA-modified asphalt binder. On this basis, the Gel permeation chromatography (GPC) test was used to understand the molecular weight transformation and therefore evaluate the sensitivities of the two tests in revealing the storage stability of PMA. According to the results, 2% PPA is capable to enhance the asphalt binder softening point from 60 ℃ to about 85 ℃. Similarly, the increased PPA contents could also decrease the non-recoverable compliance. When the PPA contents increase from 0% to 2%, the large molecular size proportions climb from 13.5% to about 16%. In addition, PPA with suitable content could enhance the storage stability of the SBR-modified asphalt binder. Yet the softening point difference of asphalt binder containing 1% PPA is merely 0.5 ℃ and reveals the least phase separation according to softening point results, which is contradictory to the best PPA dosage of 0.5% shown in the MSCR and GPC tests. Furthermore, the MSCR test shows better correlations with the GPC test with a correlation coefficient of 0.82. Combining the storage stability and ductility results, the 0.5% PPA content is potential to decrease the phase separation of SBR-modified asphalt binder without substantially weakening the low-temperature performance.]]></description>
      <pubDate>Thu, 21 Jul 2022 11:30:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/1976990</guid>
    </item>
    <item>
      <title>Improvements on the use of GPC to measure large-size microstructures in aged asphalt binders</title>
      <link>https://trid.trb.org/View/1970176</link>
      <description><![CDATA[Gel permeation chromatography (GPC) is commonly used to study the aging and rejuvenation behaviours of asphalt binders, as the sizes of molecules and microstructures in asphalt binders change in such processes. The filtration procedure in preparing GPC specimens, however, may filter out some large-size microstructures in asphalt, making the measured molecular size distribution biased. To investigate this issue, two laboratory-aged asphalt binders and seven recovered ones were studied. Substances filtered from asphalt binders were analysed gravimetrically, followed by examinations using scanning electron microscope (SEM) and scanning transmission electron microscope (STEM). Relationships between binders’ rheological properties and the proportion of large molecular size (LMS) content based on the GPC chromatogram were investigated before and after counting the filtered substances. Results show that microstructures in the recovered asphalt binders differ from those in laboratory-aged ones in both size and morphology. While about 1% of laboratory-aged asphalt binders is obstructed by the GPC filter, 6–10% of recovered ones are blocked. Adding the filtered substances results in better correlations between the rheological properties and the proportion of LMS content. Therefore, in using GPC to analyze aged asphalt binders, it is recommended to count the filtered substances as part of LMS content.]]></description>
      <pubDate>Mon, 20 Jun 2022 15:31:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/1970176</guid>
    </item>
    <item>
      <title>Microscopic experimental and numerical research on rejuvenators: A review</title>
      <link>https://trid.trb.org/View/1920749</link>
      <description><![CDATA[Prompting high content of reclaimed asphalt pavement (RAP) to be used in road building and maintenance has drawn great attention. The application of rejuvenators is an efficient way to ensure the performance of recycled asphalt mixtures. However, as various types of rejuvenators emerging, limited understanding about rejuvenation poses challenges to put effective ones into use. For precisely evaluating the performance of rejuvenators, plenty of studies were conducted to ascertain the fundamental mechanism of rejuvenating from the microscopic view. This paper provides an overview of studies focusing on the change inside asphalt after adding rejuvenators. Chemical compositions of rejuvenators were collected as basic information. Both laboratorial experiments and molecular dynamic simulations were investigated to not only compare the effectiveness of several rejuvenators but also explain the rejuvenating mechanism. Finally, functional groups of rejuvenator structures were comprehensively examined to provide global understanding about how chemical compositions influence the efficacy of rejuvenators. This review highlights that the essential capacity of a true rejuvenator is to disturb asphaltene agglomerations. Besides, the molecular structures of rejuvenators will not only affect their deagglomerating abilities but also the performances of diffusion and durability. It has been found that gel-permeation chromatography (GPC) analysis is effective in evaluating the performance of rejuvenators, while Fourier transform infrared spectroscopy (FT-IR) and SARA (saturates, aromatics, resins and asphaltenes) analysis are only suitable for assessing asphalt oxidization. In addition, comparing some tests can only detect changes, molecular dynamic simulation can reveal the mechanism both of data and vision. The results of this work can provide comprehensive knowledge for the evaluation and development of rejuvenators.]]></description>
      <pubDate>Fri, 25 Mar 2022 12:36:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1920749</guid>
    </item>
    <item>
      <title>A revised relationship between molecular weight and reduced angular frequency in δ-method applied to unmodified petroleum bitumens</title>
      <link>https://trid.trb.org/View/1919012</link>
      <description><![CDATA[The δ-method has been developed to estimate molecular weight distributions of bitumens from phase-angle master curves. The method uses a correlation between the cross-over frequency(ωC) and the molecular weight (MW) that was developed from average MW measured by vapour pressure osmometry. This study proposes a revised correlation whose parameters have been calculated from Gel Permeation Chromatography (GPC), which can be conducted at a low level of dilution preserving the interactions in the bitumen bulk. Furthermore, data from the GPC allow the optimisation of the parameters considering the entire MW distribution (MWD), thus improving the predictive capability of the method. Three unmodified petroleum bitumens at different levels of ageing and three rheological models were used in the optimisation. Two groups of parameters were identified; one for hard (e.g. Pen 35-50) and another one for soft-medium bitumens (e.g. Pen 50–70 or Pen 70-100). The apparent-MWDs (A-MWDs) calculated with the new parameters show improved correlation with the respective distributions and average molecular weight from GPC.]]></description>
      <pubDate>Thu, 24 Mar 2022 17:26:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1919012</guid>
    </item>
    <item>
      <title>Gel permeation chromatography-based method for assessing the properties of binders in reclaimed asphalt pavement mixtures</title>
      <link>https://trid.trb.org/View/1899023</link>
      <description><![CDATA[Evaluating the properties of asphalt in reclaimed asphalt mixture (RAP) is a crucial step in the design of hot recycled mixtures. The conventional assessment approach involves the extraction and recovery of the aged asphalt with further assessing the aging condition of recovered binders via their penetration, viscosity, and performance-related properties. Since this approach is time-consuming, environmentally unfriendly and involve residue mineral powders that may alter the recovered binder properties, an alternative gel permeation chromatography-based method, requiring no extraction or recovery, was proposed in this study. The gel permeation chromatography (GPC) test were carried out to directly analyze the Large molecular size (LMS) content of unrecovered binders in asphalt mixture samples under different aging conditions, which were prepared via laboratory simulated aging procedure. LMS content was found sensitive in reflecting the aging condition for the binders in the mixture. In addition, the correlation between the aging levels of asphalt mixtures aged under laboratory conditions with those of single asphalt samples was established. Following this, the best-fit regression model linking the LMS content in a mixture sample with the rutting factor, penetration and viscosity were developed. According to the above regression model, the conventional properties of RAP binders were predicted by their LMS content, which can be further applied to assess the aging condition of RAP binders, eliminating the complicated extraction and recovery process. Three sources of on-site RAPs verified the proposed method feasibility: it reasonably estimates the properties of binders in RAP, especially for base asphalt.]]></description>
      <pubDate>Thu, 20 Jan 2022 12:14:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1899023</guid>
    </item>
    <item>
      <title>Investigation of anti-aging mechanism of multi-dimensional nanomaterials modified asphalt by FTIR, NMR and GPC</title>
      <link>https://trid.trb.org/View/1879139</link>
      <description><![CDATA[Asphalt is susceptible to being aged when exposed to thermal, oxygen and photo environment during construction or service period. To solve this issue, researchers used different sorts of nanomaterials to bring improvements to anti-aging properties of asphalt. Multi-dimensional nanomaterials (MDN) are the substances composed of two or more kinds of nanomaterials with different dimensions. Previous studies have proved the anti-aging efficiency of MDN but its mechanism is still unclear. In this paper, base asphalt was firstly modified by 1% organic expanded vermiculite (OEVMT) and 3% inorganic particles (nano-zino oxide (ZnO), nano-silica (SiO₂), nano-titania (TiO₂)). Then thin film oven test (TFOT), pressure aging vessel (PAV) test and ultraviolet (UV) aging test were employed on all samples. Macroscopic properties changes were characterized by physical and rheological tests while microscopic chemical structure changes were observed by Fourier transform infrared spectrometer (FTIR), Nuclear transform infrared (NMR) and Gel permeation chromatography (GPC). Results showed that MDN decreases the increment in softening point, viscosity aging index and complex modulus aging index while increases the retained penetration and phase angle aging index. Meanwhile, the addition of MDN reduces length of straight chains of unaged materials shown by NMR results, which demonstrates that the internal friction decreases when asphalt molecules move. According to GPC results, the decreased amount of large molecules is attributed to the intercalated /exfoliated structure formed by OEVMT. FTIR test results illustrated that MDN is helpful to reduce the number of sulfoxide function groups because of the absorbing/ reflecting effects of inorganic nanoparticles on ultraviolet radiation.]]></description>
      <pubDate>Fri, 29 Oct 2021 15:40:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1879139</guid>
    </item>
    <item>
      <title>Investigating the field short-term aging of high content polymer-modified asphalt</title>
      <link>https://trid.trb.org/View/1870864</link>
      <description><![CDATA[High Content Polymer-Modified Asphalt (HCPMA) is gaining popularities due to its superior performance. However, high production temperatures are required during the HCPMA pavement construction, which could easily lead to serious short-term aging. This study aims to study the impact of field short-term aging on HCPMA’s chemical and rheological properties. HCPMA binders used in three field projects were recovered and examined using Gel Permeation Chromatography (GPC), Fourier Transform Infrared (FTIR) and Dynamic shear rheology (DSR). Additionally, to compare between the laboratory aging and field aging, binders recovered from the laboratory Short-term Oven Aging (STOA) as well as binders aged by Rolling Thin Film Oven Aging Test (RTFOT) were examined. The result suggests the aging effects of the standard RTFOT are too weak to simulate the field aging of HCPMA and the actual field aging level lies between RTFOT and STOA. It is also found the aging of HCPMA contains the hardening of asphalt and the degradation of SBS polymer, and the process of polymer degradation exerts more influence on the HCPMA binder’s viscoelastic response (i.e. phase angle) rather than its stiffness (i.e. modulus). After field short-term aging, HCPMA binder becomes stiffer and less elastic.]]></description>
      <pubDate>Mon, 23 Aug 2021 17:08:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/1870864</guid>
    </item>
    <item>
      <title>Blending Efficiency of Asphalt Mixtures Containing Recycled Asphalt Pavement and Shingle</title>
      <link>https://trid.trb.org/View/1858118</link>
      <description><![CDATA[This study aims to address blending issues in warm mix asphalt (WMA) and hot mix asphalt (HMA) containing recycled asphalt pavement (RAP) and recycled asphalt shingle (RAS). Two fingerprinting methods of asphalt covered in this study are gel permeation chromatography (GPC) and atomic force microscopy (AFM). Laboratory testing methods for determining blending efficiency employed in this study include determining aged binder mobilization rate and staged extraction method. The factors affecting the blending efficiency include mixing time, mixing temperature, aged binder content and effect of WMA technology. Major conclusions from the study are summarized as follows: 1) There existed a strong correlation between the percentage of large molecular size (LMS) and the complex modulus (G*) of asphalt binder based on the comparison of GPC and dynamic shear rheometer (DSR) test results. As mixing time and temperature increased, more blending occurred in the RAP/RAS mixture. The size of virgin aggregate did not affect the blending efficiency of RAS in pavement mixtures. 2) “Blending Charts” could be generated between the RAP/RAS binder content in the blend with the large molecular size (LMS%) defined by molecular weight and the relations were found to be linear. The mobilization rate of RAP binder decreased with the increase of the RAP percentage in the mixture. RAS binder mobilization rate increased with RAS percentage growing from 2.5% to 5%, but decreased with RAS percentage passing 5%. The highest mobilization rate was around 61% and found on 5% RAS mixture while the mobilization rate of mixture containing 10% RAS could be as low as 36%. 3) Trichloroethylene (TCE) was found to be the most effective solvent used in the study for staged extraction. The binder coating on the raw RAP and RAS aggregates was proved to be homogeneous and the layer stripping did occur in a well-controlled composite binder system. Based on well-designed staged extraction and GPC analysis, binder film coating virgin aggregates was approximately homogeneous in RAP mix, while a non-homogeneous binder was generated on RAP aggregates. A potential composite binder system was found coating the virgin aggregates in RAS mix. The diffusion study shows that within the mixture storage time, binder diffusion can be accomplished in both warm and hot mixes containing RAP, indicating old binder mobilization, rather than binder homogeneity, could be more critical in RAP mix. The binder diffusion in RAS mix was captured in a very slow rate. 4) WMA additives yielded higher blending ratio than control mix produced at 135°C, but the temperature of 165°C still produced the mix with the highest blending ratio value. This indicates that a concern still exists over asphalt blending even if WMA additives are used. Foaming technology yielded a higher blending ratio, indicating foamed WMA may yield a higher blending than regular HMA. It was also found that temperature rather than coating is more critical in RAS blending. 5) According to the observations, AFM proved to be capable of differentiating virgin binder from RAS binder in terms of microstructures. The microstructures of tear-off RAS binder was found to be temperature-dependent, but changed very little within the range from 60°C to 180°C. Virgin binders selected in this study could not blend through a RAS binder layer of 300 μm within 30 minutes at 180°C. On the basis of observations on the interfacial zone, RAS binder was found to be “mixing” but not “blending” in a mixing zone of 25 to 30 μm.]]></description>
      <pubDate>Mon, 12 Jul 2021 18:57:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1858118</guid>
    </item>
    <item>
      <title>Evaluating Recycling Efficiency of Asphalt Plants</title>
      <link>https://trid.trb.org/View/1845673</link>
      <description><![CDATA[This study aims to determine recycling efficiency of mixtures containing recycled asphalt pavement (RAP) and recycled asphalt shingle (RAS) from different asphalt plants and to investigate the influence of mixture design and production conditions on recycling efficiency. A new procedure was developed by using fluorescence microscopy to differentiate between RAP/RAS and virgin binders as well as their blends, in which a new parameter, mean grey value (MGV) based on fluorescence image, was utilized to quantitatively determine the mobilization rates of aged asphalt binder in RAP/RAS. By generating the “Blending Chart” to show the change of MGV with RAP/RAS binder content, the mobilization rate of aged binder in RAP/RAS can be directly measured. A total of 14 plant-produced asphalt mixtures were tested  for their RAP/RAS binder mobilization rate using fluorescence microscopy and gel permeation chromatography (GPC).  Linear regression  analyses were conducted to evaluate the influence of mixture design and production condition parameters on the mobilization rate. In addition, a preliminary study was performed to investigate the influence of different rejuvenator incorporation methods on the rheological and aging properties of asphalt binders containing RAP/RAS. The major conclusions from the study are summarized as follows: (1) The mobilization rates were different for large and small aggregates because of different RAP/RAS contents. The overall mobilization rate of a mixture could be determined by considering the surface area of large and small aggregates. (2) The overall mobilization rates of 14 plant mixtures were in the range of 0.4 to 1.0 for the fluorescence microscopy method and 0.37 to 0.83 for the GPC method. The mobilization rates from fluorescence microscopy and GPC method were different but showed similar trend among 14 plant mixtures. The R² of the linear regression between GPC and fluorescence results is 0.557. (3) Among the production condition parameters of asphalt mixture plants, the mixing temperature and the percentage of RAP/RAS showed significant influences on the mobilization rate. In addition, the ageing level of the RAP/RAS binder also had a significant influence on the mobilization rate. (4) The sensitivity of MGV to the aged binder content was affected by the test conditions. An index, Differentiation Factor, was used to measure the sensitivity of MGV to aged binder content. Results indicate that the MGV measured at the wavelength of 450-490 nm and the exposure time of 0.5-1.5 s was most sensitive to the aged binder content. For the construction of a blending chart, it was found that there existed a linear relationship between the MGV of a binder blend and its RAP binder content, and a quadratic relationship between the MGV of a binder blend and its RAS binder content.]]></description>
      <pubDate>Mon, 07 Jun 2021 09:44:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1845673</guid>
    </item>
    <item>
      <title>Microscopic performance of modified asphalt based on aging</title>
      <link>https://trid.trb.org/View/1842387</link>
      <description><![CDATA[In order to clarify the effect of modified asphalt after thermal aging (aging for short) on asphalt pavement performance, five groups of asphalt samples were selected as research materials: matrix asphalt group, styrene-butadiene-styrene (SBS) group, styrene-butadiene rubber (SBR) group, stabilizer group and furfural extract oil group. The changes of macro-performance and micro-structure for asphalt were compared and analyzed before and after aging. The micro-morphology of asphalt surface was analyzed by scanning electron microscope (SEM). The cross linking and degradation of asphalt molecules was observed by gel permeation chromatography (GPC). The high temperature performance and exothermic properties were analyzed by differential scanning calorimetric (DSC). The results showed that agglomeration increased with aging and occurred in all asphalt samples, but most particles of composite modifier were evenly distributed and with a few folds being on the surface of the modified asphalt after aging. Double peaks appeared in the chromatogram of the SBS modifier before aging, but only single peak appeared after aging. The chromatogram peak of composite modifier shifted to the right after aging, and the peak of composite modifier was not obvious and dispersed widely. There was a weak exothermic peak from 350 °C to 410 °C in the DSC curve of the asphalt sample and a strong endothermic peak from 420 °C to 510 °C before and after aging. The maximum endothermic peak was at 460 °C. Except for the SBR group, the bond-breaking endothermic rate of macromolecules was higher than that of polymerization exotherm of small molecules during long-term aging, so the heat absorption of long-term aging asphalt was greater than that of short-term aging. The analysis of macro results showed that the comprehensive performance of composite modified asphalt was the best, which had a positive significance for improving the pavement performance and application of modified asphalt.]]></description>
      <pubDate>Wed, 21 Apr 2021 16:17:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1842387</guid>
    </item>
    <item>
      <title>Microstructure and rheological response of laboratory-aged SBS-modified bitumens</title>
      <link>https://trid.trb.org/View/1765061</link>
      <description><![CDATA[Polymer additives are widely used to improve the performance of road bitumens including their resistance to hardening during oxidation, although their oxidative inhibitor effect has not been well documented. This study aims to investigate the effect of laboratory-simulated ageing on the microstructure, and rheological properties of Polymer Modified Bitumens (PMBs) prepared with a Styrene-Butadiene-Styrene (SBS) copolymer and sulphur as a cross-linker. The laboratory ageing was conducted through the Rolling Thin Film Oven (RTFO) and the Pressure Aging Vessel (PAV) procedures. The unaged and aged binders were characterised using the Multiple Stress Creep and Recovery (MSCR) test, Gel Permeation Chromatography (GPC) and fluorescence microscopy. The MSCR test showed that the cross-linked polymer had a higher capability of mitigating the effect of bitumen hardening on the rheological response, while for the PMBs without cross-linking, the polymer effects decreased significantly after RTFOT ageing. The GPC results showed that the aromatics, resins and asphaltenes fractions of the unmodified bitumens shifted towards heavier molecules after one cycle of PAV ageing but showed limited variation with further ageing. Similar behaviour was observed for the uncross-linked polymer binders, while for the cross-linked polymer binder, the behaviour depended on the polymer concentration.]]></description>
      <pubDate>Tue, 23 Mar 2021 11:13:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1765061</guid>
    </item>
    <item>
      <title>Application of gel permeation chromatography technology in asphalt materials: A review</title>
      <link>https://trid.trb.org/View/1767768</link>
      <description><![CDATA[Understanding the link between molecular composition and macro-mechanical performance of asphalt binder is crucial for the selection, modification and performance prediction of asphalt binder. As one of the chemical analysis technologies, gel permeation chromatography (GPC) provides an efficient and accurate approach to separate asphalt molecules based on the size difference. This review summarized the application of GPC in characterizing asphalt materials. The basic principle, test methods and data analysis were introduced firstly. Then the applications of GPC in asphalt materials in terms of fraction detection, modification process characterization, aging characterization, recycled asphalt evaluation, and performance prediction were systematically reviewed. Finally, several suggestions were made for the future application of GPC technology in asphalt material analysis. This review potentially provides a guide for researchers to understand the performance of asphalt binders from the perspective of molecular weight distribution, and further promotes the development of renewable, sustainable and durable asphalt materials for pavement construction and rehabilitation.]]></description>
      <pubDate>Mon, 22 Mar 2021 10:34:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1767768</guid>
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