<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3ARkmag%2A" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. 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>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>Laboratory and Mechanistic Evaluation of Influence of the Degree of Compaction on the Performance of Cement-Stabilized Full-Depth Reclamation Mixes</title><link>http://pubsindex.trb.org/view/2701107</link><description><![CDATA[Full-depth reclamation (FDR) is emerging as a sustainable solution for rehabilitating deteriorated pavements, particularly on rural and low-volume roads. However, inconsistent field performance, often attributed to inadequate compaction, has raised concerns about its long-term effectiveness. This study investigates the influence of the degree of compaction (DoC) on the mechanical and fatigue performance of cement-stabilized FDR mixes. Reclaimed pavement materials were blended to achieve the target gradation and stabilized using 5% Ordinary Portland Cement. Specimens were compacted at five DoC levels (94% to 106% of modified Proctor density) and tested for unconfined compressive strength (UCS), ultrasonic pulse velocity (UPV), flexural strength, and flexural modulus. Additionally, fatigue performance was assessed through laboratory beam fatigue testing and mechanistic analysis. Results showed significant gains in strength and fatigue life with increased compaction, UCS improved by up to 154%, UPV (a measure of material quality and homogeneity) by over 50%, and fatigue life rose from 23 million standard-axles (msa) at 94% to 214 msa at 106% DoC. However, achieving 106% DoC may pose practical challenges in the field. The study highlights that a compaction range of 100%–103% is both feasible and sufficient to yield substantial performance benefits, emphasizing the critical need for stringent compaction control in FDR projects.]]></description><pubDate>Mon, 11 May 2026 14:37:18 GMT</pubDate><guid>http://pubsindex.trb.org/view/2701107</guid></item><item><title>Impact of Fatigue Exposure on Extensibility Performance of Standard Joint Reservoir and Sealant Designs for Jointed Plain Concrete Pavements</title><link>http://pubsindex.trb.org/view/2681414</link><description><![CDATA[The transverse joint sealant for a jointed plain concrete pavement (JPCP) minimizes the entry of moisture, deicing salts, and incompressibles. This reduces the potential for the development of durability issues, erosion, pumping, faulting, spalling, and blow-ups. Sealant performance is influenced by sealant material, joint reservoir design, and the timing and quality of the installation. A laboratory study was performed to evaluate three joint design/material combinations subjected to simulated joint opening/closing and vehicle load fatigue that would occur in a 15 ft JPCP throughout a 42-year service life and freeze-thaw cycles. Data collected from an instrumented pavement was used to establish the loading conditions throughout the 42 years. Extensibility testing was performed on newly sealed joints as well as sealed joints with the simulated service life loadings to assess the performance. The adhesive strength for the asphalt sealed joints (26 pounds per square inch [psi]) was found to be statistically significantly higher than the silicone sealed joints (22 psi). Additionally, it was observed that asphalt filled joints exhibited substantial cohesive failures because of the narrow joint width and the difficulty in adequately filling the joint. From these results, it was concluded that silicone and asphalt sealant material and reservoir designs are sufficient to achieve long-term performance for 15 ft JPCPs for the JPCP design and environmental conditions considered, while asphalt filled joints are recommended for shorter slabs. These results assume that all joints are activated before sealing to prevent over- and under-filling of the joints, which can lead to premature sealant failure.]]></description><pubDate>Fri, 20 Mar 2026 08:38:25 GMT</pubDate><guid>http://pubsindex.trb.org/view/2681414</guid></item><item><title>Determination of Volumetric Criteria for Designing Hard Asphalt Mixture</title><link>http://pubsindex.trb.org/view/1759278</link><description><![CDATA[The current mix design method that established based on the volumetric properties works well for the conventional hot-mixed asphalt (HMA), but does not satisfy the design of marginal hard HMAs. Increasing asphalt content is regarded to be an effective way to design hard HMAs and keep them away from thermal problem. Therefore, this research explored the suitable volumetric criteria for designing hard HMAs. The principle of establishing the volumetric criteria is to ensure hard HMAs can achieve the comparable performance as conventional ones. Eleven groups of AC16 containing 70#, 50#, and 30# asphalt were designed, and the volumetric properties, UPST, LTBT, and 4PBT of each group were then conducted. Based on experiment data, two key volumetric criteria of VMA and AFT are established for hard HMAs. It can be seen that the 50# and 30# hard HMAs can still perform the same high- and low- temperature performance as 70# conventional HMAs, when the ranges of AFT maintain within the 10-11.2 µm and 13.1-13.4 µm, respectively, higher than 7-9 µm recommended in 70# HMAs. At the same time, the ranges of criteria in VMA for 50# and 30# hard HMAs need to be adjusted to 15.7-17.5% and 17.9-19.5%, respectively. In addition, the results show that the harder binder can significantly contribute to improving the fatigue resistance of HMAs.]]></description><pubDate>Thu, 04 Feb 2021 10:57:26 GMT</pubDate><guid>http://pubsindex.trb.org/view/1759278</guid></item><item><title>Influence of Chemical Constituents of Asphalt Binders on Their Rheological Properties</title><link>http://pubsindex.trb.org/view/1629249</link><description><![CDATA[The goal of this study is to investigate the chemical constituents and rheological properties of three different binders used in the State of Qatar. Binders were designated as WL (source 1, low density), WH (source 1, high density) and AH (source 2, high density). Binder composition analysis was carried out using the saturates, aromatics, resins and asphaltene determinator (SAR-AD) technique. The percentages of saturates, aromatics, resins and asphaltenes were measured, and from those, the total pericondensed aromatics (TPA), absorbance aging index (AAI), and colloidal instability index (CII) were obtained and their relationship to rheological test results was investigated. In the rheological investigation, the linear viscoelastic properties of these binders were evaluated using a frequency sweep test. The rutting characteristics were evaluated using the percentage of recovery and non-recoverable creep compliance values from the multiple stress creep and recovery (MSCR) test, while the fatigue resistance was assessed using the linear amplitude sweep (LAS) test. The WL binder was found to have the highest stiffness, which is associated with the highest TPA content. From the MSCR test, the AH binder had the lowest rut resistance. This binder also had the lowest CII value, which represents the balanced chemical composition of this material. Out of the three binders, WH had the highest AAI value which is related to the least fatigue life as measured in the LAS test.]]></description><pubDate>Mon, 10 Jun 2019 15:25:58 GMT</pubDate><guid>http://pubsindex.trb.org/view/1629249</guid></item><item><title>Effects of Edge-Oxidized Graphene Oxide (EOGO) on Flexural Fatigue Behaviors of Cement Mortar</title><link>http://pubsindex.trb.org/view/1573363</link><description><![CDATA[This paper presents the flexural fatigue behavior of cement mortar mixed with edge-oxidized graphene oxide (EOGO) which is a new type of low-cost carbon nanomaterial that can reinforce cement hydration products. The compressive and flexural strength of the EOGO cement mortar mixtures are also tested for comparison with the results of fatigue tests. Test results indicate that the cement mortar containing 0.05% of EOGO by weight of cement exhibits the best flexural fatigue performance as well as compressive and flexural strengths. In addition, it is found that the EOGO mixed specimens show faster increase in flexural fatigue strains than the control mixture samples under the sinusoidal cyclic loading. This could imply that EOGO may help preventing or delaying the propagation of internal damage (e.g. micro-crack) in the cement paste in an early fatigue phase, resulting in enhanced flexural ductility of the cement mortar beams. Thus, it is concluded that the EOGO can be used as an additive, with cost competitiveness, for improving the structural fatigue performance of cementitious composites.  Keywords: Edge-oxidized graphene oxide (EOGO); Cement mortar; Flexural fatigue; Flexural strain increment; Ductility]]></description><pubDate>Fri, 01 Mar 2019 15:51:33 GMT</pubDate><guid>http://pubsindex.trb.org/view/1573363</guid></item><item><title>Bridge Superstructure Tolerance to Total and Differential Foundation Movements</title><link>http://pubsindex.trb.org/view/1508297</link><description><![CDATA[The purpose of this research was to develop a comprehensive understanding of the levels of support movements that bridges may tolerate before exceeding strength or service limit states. This research developed analytical procedures to objectively determine the acceptable levels of bridge foundation movements based upon superstructure tolerance considering AASHTO load and resistance factor design (LRFD) strength and service limit states.  Revisions to the AASHTO LRFD Bridge Design Specifications were proposed that provide rational guidance for foundation movement limits that include vertical and rotational movements.]]></description><pubDate>Wed, 11 Apr 2018 10:13:17 GMT</pubDate><guid>http://pubsindex.trb.org/view/1508297</guid></item><item><title>Multiscale Evaluation of Rejuvenated Asphalt Binders with a High RAP Content</title><link>http://pubsindex.trb.org/view/1497197</link><description><![CDATA[A properly formulated rejuvenator is a possible remedy for an asphalt with a high percentage of Reclaimed Asphalt Pavement (RAP), which is traditionally too stiff to resist premature damage due to fatigue cracking. Rejuvenated asphalt binders with high RAP have traditionally been evaluated by micro- and macro-level test methods, which are transcendental in providing binders’ molecular level properties that govern their performance properties. This paper presents the usefulness of an Atomic Force Microscope (AFM) and the nanoindentation technique to observe fatigue resistance properties of rejuvenated asphalt binders with high RAP at the atomic level. A commercial rejuvenator is applied in a Performance Grade (PG) (PG 64-22) binder blended with different percentages (25%, 40%, and 60%, by the weight of the blended binder) of a bulk RAP. The rejuvenated asphalt binder blends were subjected to routine tests such as Penetration, Rotational Viscosity (RV), and Dynamic Shear Rheometer (DSR) as well as the AFM-based PeakForce Quantitative Nanomechanical Mapping (PFQNM™) analysis. As expected, the routine test results reveal that the rejuvenator reduces the stiffness of the RAP-modified binders. The effects of rejuvenator on the RAP-blended binders are clearly evident in the morphological images and nano level mechanistic data. Modulus values of RAP blended binders reduced significantly when the rejuvenator was used. Further, the variation of modulus values in the scanned areas was significantly lower in the rejuvenated binder compared to the nonrejuvenated counterparts. Furthermore, the AFM test results also showed higher adhesion values in rejuvenated blends. Conversely, modulus values of all phases were reduced after rejuvenation process. Findings of this study will benefit the pavement professionals for assessing the effectiveness of rejuvenators in asphalt binders with high RAP contents.]]></description><pubDate>Thu, 22 Mar 2018 11:57:36 GMT</pubDate><guid>http://pubsindex.trb.org/view/1497197</guid></item><item><title>Evaluation of the Fatigue Performance of Fine Aggregate Matrices Prepared with Reclaimed Asphalt Pavements and Shale Oil Residue</title><link>http://pubsindex.trb.org/view/1496982</link><description><![CDATA[Higher proportions of reclaimed asphalt pavements (RAP) have been added to asphalt mixtures, aiming to reduce the use of virgin materials and construction costs. One limitation of such technique is the increase of the mixture stiffness, caused by the aged binder. Stiffer mixtures are more prone to cracking and rejuvenating agents have been used to reduce the stiffness of the aged binder. The cracking process begins as micro cracks at discontinuities of the fine portion of the asphalt mixture, and studies with the fine aggregate matrix (FAM) have been developed, based on such interpretation of the fatigue phenomenon. Such technique was used on this work in order to evaluate the incorporation of RAP and rejuvenating agent on the fatigue performance of new asphalt mixtures. One source of RAP was used at three percentages (0, 20 and 100%) and a shale-oil residue was used as rejuvenating agent at three percentages (0, 50 and 100%). The addition of RAP increases the stiffness and the damage evolution rates of the FAMs, resulting in lower fatigue lives, as compared to the reference FAM. The FAM prepared with new asphalt presented fatigue performance greater than the FAMs prepared with asphalt/agent ratios of 50/50 or 0/100. The use of only a new binder of PG 64 is the best option to correct the binder content of FAMs produced with 20% of RAP. The unexpected bad performance of the shale oil residue is probably due to the low diffusion rate of the material into the aged binder.]]></description><pubDate>Thu, 22 Mar 2018 11:57:34 GMT</pubDate><guid>http://pubsindex.trb.org/view/1496982</guid></item><item><title>Investigation of Relationship between Train Speed and Bolted Rail Joint Fatigue Life using Finite Element Analysis</title><link>http://pubsindex.trb.org/view/1495615</link><description><![CDATA[Reducing the allowable operating speed or imposing temporary speed restrictions are common practices to prevent further damage to rail track when defects are detected related to certain track components. However, the speeds chosen for restricted operation are typically based on past experience without considering the magnitude of the impact load around the rail joints. Due to the discontinuity of geometry and track stiffness at the bolted rail joints, an impact load always exists. Thus, slower speeds may not necessarily reduce the stresses at the critical locations around the rail joint area to a safe level. Previously, the relationship between speed and the impact load around the rail joints has not been thoroughly investigated. Recent research performed at the University of Illinois at Urbana-Champaign (UIUC) has focused on investigating the rail response to load at the joint area. A finite element model (FEM) with the capability of simulating a moving wheel load has been developed to better understand the stress propagation at the joint area under different loading scenarios and track structures. This study investigated the relationship between train speed and impact load and corresponding stress propagation around the rail joints to better understand the effectiveness of speed restrictions for bolted joint track. Preliminary results from this study indicate that the contact force at the wheel–rail interface would not change monotonically with the changing train speed. In other words, when train speed is reduced, the maximum contact force at the wheel–rail interface may not necessarily reduce commensurately.]]></description><pubDate>Mon, 12 Mar 2018 15:02:04 GMT</pubDate><guid>http://pubsindex.trb.org/view/1495615</guid></item><item><title>Effects of Regular and Nano Sized Hydrated Lime Fillers on Fatigue and Bond Strength Behavior of Asphalt Mastic</title><link>http://pubsindex.trb.org/view/1493114</link><description><![CDATA[The present study evaluates effects of regular sized hydrated lime (RHL) and nano sized hydrated lime (NHL) on fatigue and bond strength of asphalt mastic. The asphalt mastics were produced in the laboratory using AC-30 binder with different combinations of basalt–RHL, and basalt–NHL fillers. The dosages of RHL and NHL were selected as 0%, 5%, 10%, 15%, and 20% by weight of asphalt binder, and the percentage of basalt filler was adjusted accordingly. Filler to binder (F/B) ratio was selected as 0.8 (by mass ratio) for all mastic sample preparation. The fatigue damage behavior (number of cycles to fatigue damage/failure) of asphalt mastic was evaluated using a linear amplitude sweep (LAS) test. Further, the interfacial bond strengths of asphalt mastic and aggregate samples were evaluated using the bitumen bond strength (BBS) test. Overall test results indicate that mineralogy, surface area, and interaction properties of RHL and NHL fillers have a significant effect on fatigue, bond strength, and moisture damage performance of asphalt mastic. The results from the LAS test showed that NHL filler predominantly enhanced the fatigue life of asphalt mastic as compared with RHL filler. BBS test results imply that the contribution of NHL filler is significant over RHL filler in improving the bond strength and moisture damage resistance of asphalt mastic. Overall asphalt mastic with 20% NHL filler had better fatigue life, bond strength, and moisture damage performance over mastic with other percentages of RHL or NHL fillers.]]></description><pubDate>Sun, 21 Jan 2018 17:53:28 GMT</pubDate><guid>http://pubsindex.trb.org/view/1493114</guid></item><item><title>Comparison of Laboratory Performance of Asphalt Mixes Containing Different Proportions of RAS and RAP</title><link>http://pubsindex.trb.org/view/1393715</link><description><![CDATA[Despite environmental and economic advantages associated with incorporating recycled asphalt shingles (RAS) and reclaimed asphalt pavement (RAP) in hot-mix asphalt (HMA), concerns focus on fatigue and low-temperature cracking potential of pavements containing RAS and RAP. This study was undertaken to identify the areas in need for research through conducting a national survey among departments of transportation and to evaluate the effects of RAS and RAP on fatigue, low-temperature cracking and stiffness of HMA. National survey results indicated that while the fatigue cracking is the major concern when RAS and/or RAP are used in mixes, no specific test is recommended for fatigue evaluation of these mixes at the mix design stage. Laboratory test results revealed that the fatigue life of mixes with a non-polymer-modified binder containing a blend of 5% RAS and 5% RAP led to the maximum increase in fatigue life, while using 6% RAS decreased the fatigue life, when compared with that of virgin mix. However, the use of a polymer-modified binder was found as an effective way to increase the fatigue life of the mixes. Also, it was found that addition of RAS and/or RAP to asphalt mixes increased their dynamic moduli which may result in a better rutting performance. From creep compliance test results it was concluded that use of RAS and/or RAP may lead to a higher low- temperature cracking potential when compared with the virgin mixes. Findings of this study can be used to develop/update guidelines/special provisions for design of HMA containing RAS and RAP.]]></description><pubDate>Tue, 29 Mar 2016 09:36:05 GMT</pubDate><guid>http://pubsindex.trb.org/view/1393715</guid></item><item><title>Advanced Experimental Evaluation of Asphalt Mortar for Induction Healing Purposes</title><link>http://pubsindex.trb.org/view/1393391</link><description><![CDATA[This paper studied the induction heating and healing capacity of asphalt mortar by adding electrically conductive additives (e.g. iron powder and steel fibers), and examined the influence of different combinations of them on the mechanical response of asphalt mortars. Induction heating technique is this innovative asphalt pavement maintenance method that is applied to the conductive asphalt concrete mixtures in order to prevent the formation of macro-cracks by increasing locally the temperature of asphalt mixtures. It was found that increasing steel fiber content within the asphalt mortar the tensile strength and the fatigue life increased respectively. It was also proved that the conductive asphalt mortars with iron powder appeared improved mechanical response when steel fibers were added. Furthermore, it was observed that asphalt mortars containing a combination of additives – steel fibers and iron powder - demonstrate a better induction heating efficiency than mortars including only steel fibers. Finally, the induction healing capacity of conductive asphalt mortars is determined.]]></description><pubDate>Thu, 24 Mar 2016 10:49:12 GMT</pubDate><guid>http://pubsindex.trb.org/view/1393391</guid></item><item><title>Evaluation of Additional Laboratory Tests for the Design of Cold In place Recycled Mixtures Using Foamed Bitumen</title><link>http://pubsindex.trb.org/view/1392475</link><description><![CDATA[The mix proportion design methods for full depth reclamation mixtures using foamed bitumen (FB) normally fix a constant active filler content and indirect tensile strength (ITS) test is used to determine the optimum bitumen content. However, it has been reported in the literature that for some materials ITS test is not sufficiently sensitive to bitumen content. This is a problem for the practitioner engineer who has to validate the bitumen content adopted in the mixture design. The main objective of this work is to examine the sensitivity to bitumen content of additional laboratory tests that could complement current design methods based on ITS. The mixtures used in the study were prepared using three recycled reclaimed asphalt pavement (RAP)/aggregate blends that were mixed with bitumen foam contents of 1.25%, 2.5% and 3.75%. Test results confirmed the low sensitivity of ITS, and it was found that Indirect Tensile Fatigue (ITF) test was the most sensitive among all tests. To explain the higher sensitivity of ITF test compared to ITS, a stress-strain diagram and a simple unidirectional mechanical model were developed. In addition, an S-N fatigue diagram was used to illustrate that at a larger number of load cycles, the effect of the FB content is clear as shown in the experimental work. Overall, the laboratory program and material behavior analysis indicate that when ITS test does not provide conclusive results the laboratory program should be complemented with ITF tests to determine the optimum FB content with more reliability.]]></description><pubDate>Thu, 04 Feb 2016 08:37:26 GMT</pubDate><guid>http://pubsindex.trb.org/view/1392475</guid></item><item><title>Laboratory Fatigue and Toughness Evaluation of Fiber-Reinforced Concrete</title><link>http://pubsindex.trb.org/view/1338479</link><description><![CDATA[Concrete pavement design is currently centered on steel reinforcement: whether in the form of dowel bars, as in jointed plain concrete pavement, or in the form of continuous rebar reinforcement, as in continuously reinforced concrete pavement. The use of steel in concrete pavements presents durability problems because of the corrodibility of steel. This study evaluated the use of polypropylene fibrillated fibers, polypropylene macrofibers, and carbon fibers as primary reinforcement in concrete pavements for the Louisiana Department of Transportation and Development. Results showed that fiber reinforcement can be used to improve both the fatigue and toughness performance of concrete. When post-cracked strength or toughness was the concern, concrete containing more fibers and fibers with a high tensile strength was desirable. Carbon fibers maintained greater load-carrying capacity at lower deflections than did the steel fibers, which produced the greatest ductility. However, toughness and fatigue performance did not correlate for small deflections; this result suggests that polypropylene macrofibers may be adequate for repeated, low-stress loading. This study also found that when repeated low deflections were a concern, such as with pavements, there had to be sufficient fibers across a crack to maintain a tight crack. Conversely, too many fibers prevented adequate consolidation and aggregate interlock and negatively influenced performance. The resultant pavement design, continuously fiber-reinforced concrete pavement, will provide an alternative to jointed plain concrete pavement and continuously reinforced concrete pavement in highway pavement design that is not susceptible to durability problems associated with corrosion of reinforcement.]]></description><pubDate>Thu, 26 Feb 2015 10:03:53 GMT</pubDate><guid>http://pubsindex.trb.org/view/1338479</guid></item><item><title>Evaluation of Fatigue Life of Asphalt Mixtures Through Dissipated Energy Approach</title><link>http://pubsindex.trb.org/view/1336866</link><description><![CDATA[Fatigue cracking constitutes a main type of distress for flexible pavement, and therefore developing adequate fatigue models is one of the key challenges in the mechanistic-empirical design method. One of the most popular test procedures used to determine susceptibility to fatigue cracking in the laboratory is the beam flexural test. The results are usually interpreted in terms of a relationship between applied stress or strain and number of cycles to failure. Although this phenomenological approach provides some guidance necessary to understand fatigue performance of asphalt concrete pavements, it is essentially an empirical approach that requires continuous calibration since the relationship between the parameters is not unique and depends on material properties and loading mode, among others. The dissipated energy approach is based on the determination of the plateau value (PV), a fundamental property which has a unique relationship with the fatigue life of asphalt mixtures. The main objective of this research was to evaluate the dissipated energy approach as an alternative to assess the fatigue life of asphalt mixtures in Costa Rica. This study used historical data from the beam flexural fatigue test to validate the relationship between the plateau value and the number of cycles to failure and evaluated several models for the prediction of PV. The results showed that the dissipated energy approach is a more accurate alternative for fatigue analysis and the models developed can eventually be applied to pavement design without the need for extensive testing.]]></description><pubDate>Thu, 26 Feb 2015 10:03:41 GMT</pubDate><guid>http://pubsindex.trb.org/view/1336866</guid></item></channel></rss>