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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=PHNlYXJjaD48cGFyYW1zPjxwYXJhbSBuYW1lPSJkYXRlaW4iIHZhbHVlPSJhbGwiIC8+PHBhcmFtIG5hbWU9InN1YmplY3Rsb2dpYyIgdmFsdWU9Im9yIiAvPjxwYXJhbSBuYW1lPSJ0ZXJtc2xvZ2ljIiB2YWx1ZT0ib3IiIC8+PHBhcmFtIG5hbWU9ImxvY2F0aW9uIiB2YWx1ZT0iMCIgLz48L3BhcmFtcz48ZmlsdGVycz48ZmlsdGVyIGZpZWxkPSJpbmRleHRlcm1zIiB2YWx1ZT0iJnF1b3Q7Q2hlbWljYWwgYm9uZCZxdW90OyIgb3JpZ2luYWxfdmFsdWU9IiZxdW90O0NoZW1pY2FsIGJvbmQmcXVvdDsiIC8+PC9maWx0ZXJzPjxyYW5nZXMgLz48c29ydHM+PHNvcnQgZmllbGQ9InB1Ymxpc2hlZCIgb3JkZXI9ImRlc2MiIC8+PC9zb3J0cz48cGVyc2lzdHM+PHBlcnNpc3QgbmFtZT0icmFuZ2V0eXBlIiB2YWx1ZT0icHVibGlzaGVkZGF0ZSIgLz48L3BlcnNpc3RzPjwvc2VhcmNoPg==" 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>
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    <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>Development and self-healing properties of a novel bio-based polyurethane (PU) modified asphalt containing dynamic covalent bonds</title>
      <link>https://trid.trb.org/View/2612517</link>
      <description><![CDATA[A bio-based variant of polyurethane (PU)-modified asphalt that incorporates dynamic covalent bonds has been developed to broaden its application range. Based on bio-based polyurethane and modified asphalt primarily derived from castor oil (CO), this study systematically examined the modification mechanism, essential physical properties, viscosity, compatibility, rheological behavior, and self-healing abilities. The results show that the viscosity of the asphalt modified with polyurethane, at different blending ratios, satisfies the necessary standards while preserving outstanding phase compatibility and improved flexibility at low temperatures. At 25 °C, the modified asphalt demonstrates exceptional self-healing properties. The S-S bonds promote polyurethane chain entanglement, forming a reversible network structure within the base asphalt. With gentle temperature stimulation, the disulfide bonds hasten the dynamic exchange process through heat absorption, which aids in restoring the network structure created by polyurethane molecules on the asphalt surface, thus improving its durability. Additionally, the characteristics of modified asphalt at both elevated and reduced temperatures first enhances with a rise in modifiers before eventually decreasing. Following the aging process, the characteristics of the asphalt samples related to both high and low temperatures, as well as their self-healing capabilities, decline. In conclusion, these results provide significant empirical knowledge for creating bio-based PU-modified asphalt that utilizes dynamic covalent bonds, alongside polymer-modified asphalt featuring self-healing capabilities.]]></description>
      <pubDate>Fri, 19 Dec 2025 10:19:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2612517</guid>
    </item>
    <item>
      <title>Introducing dynamic disulfide bonds: A new strategy for enhancing the comprehensive performance of high content polyurethane modified asphalt</title>
      <link>https://trid.trb.org/View/2607242</link>
      <description><![CDATA[High-content polyurethane-modified asphalt exhibits superior high-temperature performance and low-carbon construction advantages but suffers from compromised low-temperature flexibility. This work introduces dynamic disulfide bonds into high-content polyurethane-modified asphalt by replacing conventional chain extenders (4,4′-methylene-bis(2-chloroaniline)) with aromatic 2,2′-diaminodiphenyl disulfide and linear 3,3′-dithiodipropionic acid to develop a more durable and balanced-performance modified asphalt material. Mechanical tensile and dynamic shear rheology tests identified an optimal molar substitution ratio of 16 % for dynamic disulfide bonds. Subsequently, the effects of the dynamic disulfide bonds on the high-/low-temperature rheological properties and fatigue resistance of modified asphalt were investigated, while the chemical structure and thermodynamic impacts were also investigated by Fourier transform infrared spectroscopy and differential scanning calorimetry tests. The results showed that the introduction of dynamic disulfide bonds increased the elongation at break of modified asphalt by more than 55 %, despite the reduction in its tensile strength and complex modulus, while effectively maintaining its high-temperature rutting resistance. And multiple stress creep recovery tests revealed that the chain extenders containing dynamic disulfide bond can well maintain the high-temperature permanent deformation resistance and deformation recovery ability of modified asphalt. Concurrently, the introduction of dynamic disulfide bonds can improve its low-temperature entropy elasticity and creep performance (32.3 % increase in m-value), significantly enhance its low-temperature cracking resistance, with the linear 3,3′-dithiodipropionic acid showing superior effectiveness as evidenced by the lower glass transition temperature. Furthermore, the introduction of dynamic disulfide bonds can substantially improve the maximum strain capacity and strain energy by more than 35 %, while the fatigue life at 2.5 % and 5.0 % strain levels rose by more than 39 % and 31 %, respectively, with the linear 3,3′-dithiodipropionic acid exhibiting superior performance. This work provides novel design principles and theoretical support for designing durable thermosetting polyurethane-modified asphalt with balanced performance.]]></description>
      <pubDate>Mon, 24 Nov 2025 10:23:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2607242</guid>
    </item>
    <item>
      <title>A comparative study on the characteristics and alteration mechanism of terminal blend crumb rubber-modified bitumen with crosslinking additives</title>
      <link>https://trid.trb.org/View/2584559</link>
      <description><![CDATA[This study presents a comparative analysis of the characteristics and alteration mechanisms of terminal blend (TB) crumb rubber-modified bitumen (CRPMB) incorporating crosslinking additives (CLAs). The vulcanized structure of crumb rubber particles (CRPs) limits their dissolution in bitumen, resulting in a thermodynamically unstable binder. To address this, the study aims to improve CRP integration by incorporating sulfur and trans-polyoctenamer (TOR) as CLAs during the initial mixing stage of the TB process. The study investigated the rheological behavior of TB-CRPMB and its extracted liquid phases under varying temperature, strain, and frequency conditions, along with rutting resistance, viscosity, storage stability, chemical structure, thermal stability, and microstructure, to gain a deeper understanding of the modification mechanisms influencing binder performance. Without CLAs, TB-CRPMB showed high viscosity and poor storage stability, driven by hydrodynamic interactions. CLA addition significantly improved storage stability, workability, aging resistance and intermediate-temperature performance. Sulfur acted as both a chemical crosslinker and physical filler, improving storability and workability, while TOR functioned solely as a crosslinker, offering better thermal and long-term aging stability. High-temperature properties of TB-CRPMB showed a strong correlation with the aliphatic index. CRP dosage primarily influenced mechanical behavior, whereas CLA enhanced CRP-bitumen compatibility, facilitating the development of a durable and storable TB-CRPMB.]]></description>
      <pubDate>Mon, 15 Sep 2025 10:34:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2584559</guid>
    </item>
    <item>
      <title>The effect of glass beads sizes and surface treatment on the bonding performance of asphalt pavement marking</title>
      <link>https://trid.trb.org/View/2564291</link>
      <description><![CDATA[Glass beads (GBs) are commonly used for pavement marking to provide continuous reflective capabilities at night. This evaluation aimed to assess the influence of particle size and surface treatment on the bonding performance between the marking and asphalt pavement surface. GBs were modified using silane coupling agent and hydrofluoric acid for enhancing the bond with the marking paints. The effectiveness of the modification and the changes in functional groups on the surface of GBs were evaluated. Additionally, image processing technology was employed to analyze changes in the roughness of GBs after surface treatment. Subsequently, the influence of GBs with different particle sizes and modification methods on the adhesion properties was investigate through wheel abrasion test. The bonding strength between the marking paint and the asphalt pavement surface was then explored through direct pull-out test, considering different dosages, particle sizes, and modification methods of GBs. The test results indicated that surface-modified GBs exhibit improved bonding properties with paints. Notably, GBs modified by coupling with hydrofluoric acid and silane coupling agents demonstrated the optimum improvement in bonding behavior. The contact area between the wheel and pavement marking was also investigated in terms of various GBs particle sizes. The premixed 35 wt% modified GBs paints with 100 mesh size exhibited the strongest bonding performance with the asphalt pavement surface. This study provides the applicable technique for enhancing the bonding performance between marking and pavement surface for a better abrasion resistance and thus a longer service life.]]></description>
      <pubDate>Thu, 26 Jun 2025 16:12:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2564291</guid>
    </item>
    <item>
      <title>Crosslinking sites of sulfur and asphalt molecules: A DFT and macroscopic experimental study</title>
      <link>https://trid.trb.org/View/2541616</link>
      <description><![CDATA[In SBS-modified asphalt, additive sulfur acts as an anchor for both asphalt and SBS, preventing phase separation. However, the sulfur-asphalt crosslinking mechanism is still largely speculative, with the reactive sites on asphalt and the factors influencing reaction activity yet to be fully defined. Therefore, this study examines the reaction sites and mechanisms of sulfur-asphalt crosslinking through Density Functional Theory (DFT). First, the crosslinking sites on asphalt were classified based on their structural characteristics, and the bond dissociation energies (BDE) at these sites were calculated to predict reactive positions. Next, the adsorption energies of sulfur radicals, the free energy barriers of crosslinking reactions, and the adsorption energies between radicals were computed. This enabled a comprehensive elucidation of the reaction steps involved in sulfur radical crosslinking with asphalt, resulting in the identification of potential crosslinking sites within the asphalt structure. It was determined that sulfur radicals and asphalt molecules undergo three main stages: adsorption, attack, and crosslinking. The attack of sulfur radicals on asphalt molecules, which leads to the formation of asphalt radicals, necessitates overcoming a significant free energy barrier, which represents the critical step in the crosslinking process. In addition, the aromatic ring in asphalt forms a P-π conjugation with α-carbon, lowering the free energy barrier and becoming a key factor in crosslinking. The size and proximity of the aromatic ring were identified as secondary factors. Finally, the DFT calculations were validated through Fourier transform infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonance (H NMR). This study provides a theoretical foundation for investigating chemically cross-linked SBS-modified asphalt at the molecular level.]]></description>
      <pubDate>Thu, 15 May 2025 08:26:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/2541616</guid>
    </item>
    <item>
      <title>Polyurethane-modified asphalt mechanism</title>
      <link>https://trid.trb.org/View/2491465</link>
      <description><![CDATA[With the increasing development of transportation, the demands for the performance and lifespan of asphalt used in road construction have become increasingly stringent. However, most current road asphalt materials exhibit deficiencies in durability. To address the issue of insufficient durability in road asphalt, this paper introduces a novel polymer-modified asphalt utilizing polyurethane as a modifier and investigates the modification mechanism of this asphalt. The feasibility of using polyurethane as a modifier and its effects on matrix asphalt were analyzed using scanning electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy. Additionally, molecular dynamics simulations were employed to analyze the radial distribution function, adhesion energy, and cohesive energy density of asphalt before and after the addition of polyurethane at the microscopic structural level, revealing the molecular motion trends and interfacial bonding forces of the four components of asphalt.The results indicate that the incorporation of polyurethane leads to changes in the absorption peaks of matrix asphalt, a reduction in the "honeycomb" structure, and shrinkage. Simultaneously, improvements were observed in the radial distribution function, adhesion energy, and cohesive energy density. These findings suggest that a chemical reaction occurs between polyurethane and matrix asphalt, and the addition of polyurethane effectively enhances the orderliness of asphalt molecules and the interfacial bonding performance.]]></description>
      <pubDate>Wed, 29 Jan 2025 17:00:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2491465</guid>
    </item>
    <item>
      <title>Thermal sensitivity of CFRP/Steel bond exposed to prolonged water ingress</title>
      <link>https://trid.trb.org/View/2301004</link>
      <description><![CDATA[Carbon Fiber Reinforced Polymer (CFRP) strengthened steel outdoor and submerged structures could be often exposed to water at a range of temperatures. According to the authors' knowledge, no study has identified the effects of water temperature on bond performance, even though a range of temperatures is experienced by the strengthened structures in different parts of the world. In addition, almost all studies focused on corroded steel strengthened with CFRP have been done on steel exposed to induced accelerated corrosion under laboratory conditions, which is not a correct representation of naturally corroded steel. The micro-level degradation occurs near the rusted surface due to hydrogen release from the corrosion process and may cause heavy degradation of the composite with prolonged exposure to an aggressive environment, which might not be observed from the samples with induced accelerated corrosion. Hence, it is important to evaluate the bond performance of the strengthened steel elements exposed to natural corrosion and subjected to prolonged exposure to water immersion while quantifying the effects of surface texture and temperature. A total of forty-eight steel specimens extracted from a naturally corroded steel bridge were selected. Two scenarios of surface roughness were induced by two surface preparation methods and the combined effects of temperature and moisture were key parameters. The prepared CFRP/Steel specimens were then conditioned in water at three different temperature levels for a pre-determined period of up to 1 year. The hot and cold weather exposed samples indicated a maximum strength reduction of 30 % and 18 %, respectively, while indicating the degradation in the bond line with high sensitivity to the surface roughness of the substrate.]]></description>
      <pubDate>Fri, 19 Jan 2024 16:42:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2301004</guid>
    </item>
    <item>
      <title>Preparation and characterization of polyurethane-modified asphalt containing dynamic covalent bonds</title>
      <link>https://trid.trb.org/View/2248261</link>
      <description><![CDATA[Self-healing behavior of binder has important potential for promoting low-carbon service and extending service life of asphalt pavement. A novel self-healing polyurethane modified asphalt with dynamic covalent bonds was prepared in this work. The chemical structure, thermal-oxygen stability, rheological properties, fatigue properties and self-healing capability of polyurethane modified asphalt with dynamic covalent bonds were systemically investigated through Fourier infrared spectrum test, thermal gravimetric test, dynamic shear rheology test, linear amplitude sweep(LAS) test and multiple fatigue-healing-fatigue test. The result indicates disulfide dynamic covalent bond and oxime urethane dynamic covalent bond were successfully introduced into polyurethane cross-linking structure in asphalt, and the thermal-oxygen stability of asphalt has a significant increase after modification under the environmental conditions of construction and service. Rheological properties analysis suggests the introduction of dynamic covalent bonds is beneficial to improve the low-temperature toughness of polyurethane modified asphalt, and enhances its low-temperature cracking resistance. LAS analysis indicates the fatigue life of polyurethane modified asphalt can also be lengthened by over 70% at different strain levels(1.5%, 2.5% and 5%) with the introduction of dynamic covalent bonds, which is attributed to the excellent conformation adjustment ability and stress dissipation ability of dynamic cross-linking structure in asphalt. The multiple fatigue-healing-fatigue test shows the self-healing capability of polyurethane modified asphalt has an improvement with the introduction of dynamic covalent bonds, especially at the later stage with serious fatigue damage, and oxime urethane dynamic covalent bond shows the better contribution effect as compared with disulfide bond. This is due to the reversible fracture-rearrangement characteristics of dynamic covalent bonds. This work provides a new idea for improving the self-healing capacity and rheological properties of binder, reducing the frequency of pavement maintenance and extending the pavement service life.]]></description>
      <pubDate>Thu, 12 Oct 2023 17:14:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2248261</guid>
    </item>
    <item>
      <title>Chemical characterisation of bitumen type and ageing state based on FTIR spectroscopy and discriminant analysis integrated with variable selection methods</title>
      <link>https://trid.trb.org/View/2173173</link>
      <description><![CDATA[The chemical characterization of bitumen type and ageing state are fundamental in determining structural and mechanical properties of bitumen. This work aims to classify various bitumen types at different ageing states and to identify the primary chemical differences relevant to the classification. Fourier transform infrared (FTIR) spectral data of eight bitumen types at five ageing states were analyzed using a chemometric procedure that incorporates principal component analysis (PCA), linear discriminant analysis (LDA) models, variable selection methods. The models presented results of high accuracy in differentiating bitumen type and ageing state. The results show that the spectral regions that describe the aliphatic and aromatic bonds are critical to the identification of bitumen types. The chemical changes due to bitumen ageing are mainly revealed at the region of 1800 – 900 cm-1. This chemometric method is instructive for the characterization of chemical bitumen properties.]]></description>
      <pubDate>Mon, 02 Oct 2023 16:36:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2173173</guid>
    </item>
    <item>
      <title>Preparation and performance of self-healing SBS modified bitumen based on dynamic disulfide bonds</title>
      <link>https://trid.trb.org/View/2212549</link>
      <description><![CDATA[In this study, self-healing SBS (S-SBS) was first synthesized by introducing dynamic disulfide bonds into the molecular structure of SBS. Subsequently, a self-healing SBS modified bitumen (S-SMB) was prepared by blending of S-SBS and bitumen. The chemical structure of S-SBS and S-SMB was charactered by Fourier transform infrared spectrometer (FTIR) and Raman spectrometer. The physical properties, low-temperature rheological properties and self-healing performance of S-SMB were investigated. The results of FTIR and Raman showed that dynamic disulfide bonds were successfully introduced into the molecular structure of SBS. With the increase of dynamic disulfide bonds content in SBS molecular structure, the softening point and ductility of S-SMB enhanced, and the penetration was decreased. Fluorescence microscope showed that the S-SBS in S-SMB formed a complete crosslinking network structure compared to SMB. The bending beam rheometer illustrated that the low-temperature rheological properties and the cracking resistance of SMB were improved by introducing dynamic disulfide bonds. The fluorescence microscopy observation indicated that the crack in S-SBS can self heal. The fracture healing test and fatigue healing test demonstrated that dynamic disulfide bonds endow S-SMB with great self-healing performance. The fracture healing rate of S-SMB reached 58.7% after 4 h of healing, and the fatigue healing index reached 0.93 after 1 h of healing.]]></description>
      <pubDate>Mon, 28 Aug 2023 09:34:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2212549</guid>
    </item>
    <item>
      <title>Dual dynamic bonds approach for polyurethane recycling and self-healing of emulsified asphalt</title>
      <link>https://trid.trb.org/View/2168320</link>
      <description><![CDATA[To recycle polyurethane and extend the service life of polyurethane-modified emulsified asphalt, this study developed novel perspectives for a lower carbon-footprint and cleaner preparation of recyclable polyurethane (RWPU) and its modified emulsified asphalt (RPUA-x) by using self-emulsification and dual dynamic bonds. Particle dispersion and zeta potential tests reflected that the emulsions of RWPU and RPUA-x existed excellent dispersion and storage stability. Microscopic and thermal analyses indicated that RWPU possessed dynamic bonds and maintained thermal stability below 250 °C as anticipated. Concurrently, RWPU provided RPUA-x with a strong physical cross-linking network, and a homogeneous phase was observed in RPUA-x after drying. Self-healing and mechanical evaluation results revealed that the regeneration efficiencies of RWPU were 72.3 % (stress) and 100 % (strain), respectively, and the stress-strain healing efficiency of RPUA-x was >73 %. The energy dissipation performance and plastic damage principle of RWPU were investigated using cyclic tensile loading. The multiple self-healing mechanisms of RPUA-x were revealed through microexamination. Furthermore, the viscoelasticity of RPUA-x and variations in flow activation energy were determined based on Arrhenius fitting from dynamic shear rheometer tests. In conclusion, disulfide bonds and hydrogen bonds endow RWPU with remarkable regenerative properties and grant RPUA-x with both asphalt diffusion self-healing and dynamic reversible self-healing capabilities.]]></description>
      <pubDate>Thu, 22 Jun 2023 09:49:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2168320</guid>
    </item>
    <item>
      <title>Silane coupling agent impact on surface features of modification of basalt fibers and the rheological properties of basalt fiber reinforced asphalt</title>
      <link>https://trid.trb.org/View/2095306</link>
      <description><![CDATA[Rheological properties of fiber reinforced asphalt (FRA) can be significantly influenced by the surface properties of fibers. Modified basalt fibers are emerging materials used to enhance the performance of FRA. Silane coupling agents (SCAs) make it possible to introduce versatile surface features to basalt fibers (BFs). Six typical SCAs were tested and evaluated for modifications on the rheological properties of BF reinforced asphalt at different high-level temperatures. The specific characteristics of each modified BF was measured by dynamic surface tension meter, denoted as surface energy components (SFEC), calculated using two distinct methods, OWRK (dispersive-polar approach) and vOCG (acid-base approach). The semi-quantitative correlation between SFEC based on each method and rheological properties with regard to temperature response were detailed. Study results show that Van de Waals interaction and acid-base interaction is more suitable to describe the interaction between asphalt and basalt fibers, and the interaction mechanism changes when temperature increases. Our research provides a guidance in the modification of SCAs when used in combination with mineral fillers to improve the overall performance of asphalt mixtures. Additionally, a novel SCA carrying long chain alkanes (UP312) shows high potential for modifying mineral fillers with excellent water resistance and improvement in the rutting resistance of asphalt concrete.]]></description>
      <pubDate>Wed, 22 Feb 2023 09:57:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/2095306</guid>
    </item>
    <item>
      <title>Preparation and characterization of organic red mud and its application in asphalt modification</title>
      <link>https://trid.trb.org/View/2095316</link>
      <description><![CDATA[Red mud, a promising asphalt modifier, can improve comprehensive performance of asphalt. However, the compatibility and performance of organic red mud modified asphalt are also worthy of attention. In this study, organic red mud was prepared with oxalic acid and coupling agent (also called surface modification), and then characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning microscope (FESEM), nitrogen gas adsorption–desorption system (BET) and ultraviolet visible (UV–visible) tests. The application of prepared organic red mud in asphalt modification was explored, including basic performance and aging resistance. The results show that organic red mud prepared by chemical reaction has more uniform particles distribution, smaller specific surface area and stronger ultraviolet reflectivity. After surface modification, the inorganic red mud filler changes from hydrophilic to hydrophobic, and the interaction with asphalt is enhanced, which improves the basic performance of asphalt. More importantly, organic red mud can be homogeneously dispersed in asphalt to inhibit the diffusion of heat and oxygen, and it can reduce the ultraviolet damage to asphalt. Consequently, the thermo-oxidative and ultraviolet aging resistance of asphalt are further enhanced.]]></description>
      <pubDate>Wed, 22 Feb 2023 09:57:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2095316</guid>
    </item>
    <item>
      <title>Investigation of the Influence of Aging on the Nanoscale Adhesion of Asphalt from the Perspective of AFM-IR–Based Chemical Properties</title>
      <link>https://trid.trb.org/View/1996421</link>
      <description><![CDATA[Investigation of the adhesion mechanism during the aging process of the asphalt-aggregate interface from a microscopic point of view contributes to the solution of water damage of asphalt pavements. So far, some work has been done to reveal the influence of aging on the adhesion strength of the asphalt from the nanoscale factors. However, due to the lack of direct chemical analysis means to test the chemical composition of asphalt at the nanoscale, the inferences made among different scholars are somewhat controversial. The objective of this study is to reveal the evolution of adhesion characteristics of the asphalt binders during the aging process based on their chemical components. Five asphalt binders at different aging degrees were prepared via laboratory simulated aging procedure. State-of-art technologies, atomic force microscopy–based infrared spectroscopy (AFM-IR) and AFM PF-QNM (peak force quantitative nanomechanical mapping) mode, were adopted to analyze the nanoscale adhesion and chemical components of the prepared asphalt. And binder bond strength (BBS) testing was performed to interpret and verify the nanoscale mechanism of asphalt adhesion behavior from macroscale. The results of the AFM test indicated that both sulfoxide and carbonyl functional group content contribute to the adhesion force of the asphalt binders. Compared with the carbonyl group, the sulfoxide content affects the nanoscale adhesion force more significantly. Meanwhile, the results of the BBS test are found in accordance with the AFM trends. Finally, an estimation model was established to roughly estimate the nanoscale adhesion force of asphalt at varying aging conditions based on these two functional groups.]]></description>
      <pubDate>Mon, 29 Aug 2022 09:27:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/1996421</guid>
    </item>
    <item>
      <title>Monotonic and cyclic behavior of high strength reinforcing steel (HSRS) after high temperature exposure</title>
      <link>https://trid.trb.org/View/1948951</link>
      <description><![CDATA[Conventional reinforced concrete transportation structures in North America often use Grade 60
reinforcing steel with a yield stress of 60 ksi. The introduction of high strength reinforcing steel
(HSRS) with higher yield strength in the reinforced concrete industry has led to many economic
and workability advantages such as construction time saving, reduced labor cost and steel
consumption which in turn alleviates congestion of reinforcement, savings in transportation and
deliveries that finally results in lower carbon emission. Despite these benefits, many states,
including those in Region 6, have not widely adopted the use of higher strength reinforcing
steels in practice due to lack of knowledge and comfort level with implementing new
technologies and techniques, and the serviceability and durability concerns. In addition, bridge
surveys among 18 states have shown that fire has caused more bridge collapses than
earthquakes. In general, there are three common types of ASTM steel bars that are produced
with yield stresses above 60 ksi: ASTM A615, ASTM A706 and ASTM A1035 (CL, CM and CS
based on carbon and chromium content). Given the lower ductility of HSRS rebars compared to
conventional reinforcement along with the lack of knowledge on different types of HSRS and
their behavior when exposed to elevated temperatures, studying the behavior of HSRS after
high temperature exposure is deemed to be necessary.
In this study, four different tests will be conducted on three different ASTM reinforcement (A615,
A706, and A1035): monotonic and cyclic tensile tests (high strain low cycle), pullout and endbeam
bond tests. Each test shall be performed at both ambient and elevated temperatures.
After the test, each specimen will be analyzed using Energy dispersive X-Ray (EDX) and
scanning electron microscopy (SEM) to investigate the possible change in material composition
and failure analysis of fracture surfaces, respectively. The results will be reported and compared
with the previous studies on conventional and HSRS reinforcements.
The results of this study will allow states and authorities to make more informed decisions
based on the enhanced knowledge on the behavior of HSRS in reinforced concrete
transportation structures such as bridges.]]></description>
      <pubDate>Mon, 09 May 2022 06:15:40 GMT</pubDate>
      <guid>https://trid.trb.org/View/1948951</guid>
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