<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <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" />
    <description></description>
    <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>
    </image>
    <item>
      <title>Investigation of polymer-modified bitumen containing renewable components</title>
      <link>https://trid.trb.org/View/2556817</link>
      <description><![CDATA[Researchers are exploring the possibility of replacing bitumen with renewable biomass materials to reduce the dependency on crude oil. However, to date, only marginal research has been devoted to using renewable materials to modify or partially replace polymer-modified bitumen, which is currently widely used for pavements subjected to significant heavy traffic. In this context, this study compared an SBS polymer-modified bitumen (‘PMB’) with two bio-binders consisting of PMB and components from renewable sources, including dry lignin. The binders were investigated in terms of storage stability, linear viscoelastic behaviour, fatigue performance, permanent deformation resistance, adhesion with typical aggregates and ageing susceptibility by means of physical, mechanical and chemical tests. The results show that all performance and durability properties of the studied bio-binders can be considered comparable to those of the reference PMB. These outcomes encourage the study of asphalt mixtures produced with the same bio-binders for possible application in heavy-traffic pavements.]]></description>
      <pubDate>Thu, 26 Jun 2025 11:42:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2556817</guid>
    </item>
    <item>
      <title>The role of physical and chemical methods of nanohydrated lime production on properties of bituminous binders</title>
      <link>https://trid.trb.org/View/2446208</link>
      <description><![CDATA[Nanomaterials are employed to improve bitumen's rheological properties and mechanical characteristics of asphalt mixes. The high cost of production of nanomaterials is one of the obstacles that has limited their application in road pavements. In this research, two methods of production of nanomaterials have been used to produce Nano Hydrated Lime (NHL); a mechanical process, using a planetary ball mill, and a chemical process in which some chemicals are dissolved in distilled water and then dried. The nanoparticle sizes were evaluated using Field Emission Scanning Electron Microscopy (FESEM) and Dynamic Light Scattering (DLS) tests. These were at different grinding times in the physical method, and at different solution concentrations of Calcium Nitrate (Ca(NO₃)₂) and Sodium Dodecyl Sulfate (SDS) in the chemical method. The average sizes of the nanoparticles in the physical method were 211 nm in DLS and 114 nm in FESEM (after 6 h of grinding). In the chemical method, these were 379 nm in DLS and 124.6 nm in FESEM at concentration of 3 ml of Ca(NO₃)₂ solution. X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) analysis indicated that in the physical process, higher nanolime particles were achieved. Physical properties of two bitumen types (60/70 and 85/100 penetration grades) that were modified with 2 %, 4 %, and 6 % NHL were determined using Dynamic Shear Rheometer (DSR) and Rotational Viscometer (RV) tests. Adhesion properties of the nano modified binders with three aggregate types (namely, limestone, silica, and granite) were determined using Boiling Water and Pull-Off tests. Digital images were analyzed after processing, using Digimizer Software to evaluate the percentages of the coated aggregate particles. The results indicated that the addition of 4 % NHL (in physical production method) improved best the bitumen properties. In fact with limestone aggregates, the adhesive strength ratio was increased by 38 %. Coating of bitumen on the limestone aggregates was better than that in siliceous and granite aggregates. As a result of this, the stripping percentages of the limestone aggregates were decreased the most with the addition of NHL. Finally, properties of the 60/70 pen bitumen, modified with NHL, were better than those of the 85/100 pen bitumen.]]></description>
      <pubDate>Thu, 21 Nov 2024 09:26:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2446208</guid>
    </item>
    <item>
      <title>Mechanical and rheological properties of polyurethane-polyurea (PU-PUa) modified asphalt binder</title>
      <link>https://trid.trb.org/View/2317758</link>
      <description><![CDATA[Polyurethane (PU) is one of the common polymer modifiers used for asphalt, and the PU modified asphalt currently plays a fundamental role in road constructions. However, most of the PU as the modification could bring about an increasement in viscosity and rigidity to asphalt binders, thus leading to insufficient ductility and deformation compatibility for the materials to some extent. In the present study, a composite polymer material synthesized with polyurethane and polyurea (PU-PUa) was introduced as a modifier to the asphalt binder in an attempt to integrate their individual advantages into the asphaltic material. The curing time, tensile strength, and Fourier Transform infrared spectroscopy (FTIR) tests were conducted to determine the optimal proportion of the PU and PUa in the compound polymer, and its formation mechanism was also discussed. The fundamental properties of the asphalt binders modified with various contents of PU-PUa (5%, 10%, and 15% by weight), such as the storage stability, rheological properties, creep recovery capacity, and fatigue resistance, were investigated through the thermal storage, dynamic rheological, stress creep recovery (MSCR), and linear amplitude sweep (LAS) tests. Furthermore, in order to understand the adhesion property of the PU-PUa modified asphalt on aggregates, the pull-off tests considering both dry and water immersion conditions were performed. The test results showed that the PU-PUa could be effectively used to modify asphalt binders, and 7:3 was found to be the best proportion of the PU and PUa. The addition of PU-PUa could promote the high temperature performance, enhance the recovery ability for creep, and extend the fatigue life of the asphalt binders (for both 70# and SBS asphalt). The optimal content of PU-PUa for the modification was found to be 10% based on the storage stability and mechanical performance of the modified asphalt binders.]]></description>
      <pubDate>Wed, 24 Jan 2024 09:50:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2317758</guid>
    </item>
    <item>
      <title>Improving durability of open-graded asphalt pavements : with focus on raveling performance</title>
      <link>https://trid.trb.org/View/2145737</link>
      <description><![CDATA[Durability is the main problem for the porous asphalt (PA) mixture types. The life span of this type of pavement is limited by several distress types in which raveling appears to be the most serious one. In spite of some good experiences with the PA pavements, in Jönköping, in the south of Sweden, using similar recipes in Rotebro, north of Stockholm city, resulted in severe premature raveling. In both cases highly abrasion resistant mineral aggregates, highly viscous polymer modified binder with high penetration values and Portland cement as an additive for increasing adhesion were used. Recent experience of using open graded mixtures in Sweden shows that there is still need for improving the PA pavements especially their resistance to raveling caused by infiltration of water along with extreme temperature fluctuations (freeze and thaw) during the wintertime. This process can significantly lower the adhesion between aggregates and binder in asphalt mixtures and is one of the common causes of premature failure in asphalt mixtures in cold regions like Sweden. This study focuses on finding representative evaluation methods as well as alternative materials in order to mitigate raveling in porous asphalt pavements. The long-term durability of PA related to aging is not covered in this project.  In order to achieve the goals of this study, both laboratory experiments and discrete element simulation were carried out. In the experimentation part, the three most raveling resistant PA mixtures collected from Swedish, Dutch and Japanese producers were compared for their raveling resistance. In addition, different binders and additives were examined for their potential to be used in the Swedish recipe to enhance its raveling resistance.  The evaluation part of this study was carried out using both standard and also innovative test methods. The results of the experimental part revealed the advantage of using polymer modified binders with lower penetration values over the one used in the recent Swedish PA mixture. In addition, the new test setup, i.e. high-water pressure test, appeared to enable providing an effective relative comparison among different mixtures in terms of their raveling resistance.  Discrete element simulation was also utilized in this study to build up a fundamental understanding about the impact of the truck unloading phase on causing segregation which can lead to lowering the raveling resistance of PA pavements.  The chosen methodology in this study successfully enabled providing recommendations for material selection, evaluation and also handling techniques for improving premature raveling resistance of PA pavements.]]></description>
      <pubDate>Mon, 03 Apr 2023 16:47:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/2145737</guid>
    </item>
    <item>
      <title>Optimization of surface free energy parameters for asphalt binder-aggregate system based on RBF neural network model</title>
      <link>https://trid.trb.org/View/2041947</link>
      <description><![CDATA[Asphalt pavement is subject to water damage frequently, which reduces the level of service that it provides and contributes to many road diseases. The surface free energy (SFE) theory has proven to be a trustworthy approach to assess water damage in asphalt mixtures. The goal of this investigation was to optimize the SFE parameters of asphalt binder-aggregate systems using an RBF neural network model. In this research, the SFE parameters of asphalt binder-aggregate systems were calculated firstly. Then, the modified boiling water test and the immersion Marshall test, as well as the freeze–thaw splitting test were then used to assess the asphalt mixtures’ adhesive properties and water stability. Thereafter, the comprehensive analysis method of entropy weight was used to conduct a thorough evaluation of the asphalt mixtures’ resistance to water damage. Next, the comprehensive evaluation index, Wi, of the asphalt mixtures’ resistance to water damage was used as the output layer of the RBF neural network model to optimize the SFE parameters. Finally, the feasibility of the optimized the SFE parameters using RBF neural network model was verified by establishing the connection between the optimized SFE parameters and the asphalt mixtures’ resistance to water damage by the entropy weight comprehensive analysis method. The results showed that among the SFE parameters of asphalt binder-aggregate systems optimized using the RBF neural network model, the Lewis base component and the Lifshitz nonpolar component of the aggregate played a dominant role in the ability to resist water damage, followed by the VDW adhesion work and the VDW de-bonding work formed by van der Waals forces. Furthermore, the asphalt binder-aggregate system composed of limestone had the best adhesion properties among all aggregates.]]></description>
      <pubDate>Fri, 23 Dec 2022 14:07:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2041947</guid>
    </item>
    <item>
      <title>Potential Improvements in Montmorillonite Nanoclay Modified Cold-Mix Asphalt</title>
      <link>https://trid.trb.org/View/1999061</link>
      <description><![CDATA[Over the years Cold Mix Asphalts (CMAs) used principally for pothole patching and partial-depth repairs in Ghana have performed abysmally. To justify its continued utilization in road maintenance, especially pothole patching, the material needs considerable quality improvement. One such means of improving bituminous mixtures is the use of filler materials. This study purposely incorporated a montmorillonite nanoclay (NMMT) modifier into CMAs by adopting five-dense gradation formulations from Asphalt Institute M-19 specification. Materials used include NMMT, locally-based granitic aggregates and bitumen. Using the Marshall Procedure mixture properties (Stability, Flow, Optimum Bitumen Content and Voids) were accordingly determined. Results indicate that NMM-CMA introduction significantly improves stability (24-72.7%) and optimum binder content (5.1-16%) of all gradation groups over conventional asphalt mix. The addition of 2% nanoclay is the optimum dosage to increase adhesion between bitumen and aggregate. In between the nanoclay dosages, the flow significantly increased from 1.8% to 12%. The high stability reflects the bitumen binding strength and the internal friction as a benchmark of interlocking and friction resistance of aggregates. However, NMMT-CMA would be susceptible to rutting deformation, particularly at elevated temperatures although the nanomodifier significantly increased the stability and flow of mixtures. Almost all aggregate gradation groups experienced an increase in optimum binder content (OBC) when montmorillonite nanoclay was added. Thus, the densities were enhanced while the OBC improved about 1.05 to 1.17 folds. This has significant implications for pavement technologists and researchers as one of the main benefits in various practical applications and continuous research of asphalt binder and mixture derivatives.]]></description>
      <pubDate>Thu, 27 Oct 2022 13:46:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1999061</guid>
    </item>
    <item>
      <title>Analyzing the Durability of Adhesion Stability of Asphalt Mixtures</title>
      <link>https://trid.trb.org/View/1697026</link>
      <description><![CDATA[Adhesion is one of the fundamental characteristics related to asphalt mixtures. It determines significantly the durability of asphalt mixture and depends not only on the quality of aggregate particles coating but also on the hydrophobity or hydrophility of the aggregates. For this reason often mineral-based or chemical additives are used to improve adhesion between bitumen and aggregate particles. Mainly with the latter group of additives long-term stability is connected. Amine based additives are often used which unfortunately contains easily volatile compounds. If part of the effective substance is evaporated during mixing and paving the later durability can be negatively influences. Therefore it is important not only to assess the adhesion when virgin bitumen and aggregates are used, but also the artificially aged binders or asphalt mixtures have to be evaluated. For this reason long-term research is in progress at the Czech Technical University in Prague focusing on different aggregates (different mineralogy) and different adhesion promoters. Tests are run on virgin materials as well as on specimens long-termly aged (either bitumen by RTFOT+PAV or 3xRTFOT/TFOT, or asphalt mixtures which are usually aged for 5 days at 85°C). For bitumen-aggregate adhesion determination a standardized procedure according to CSN 736161 is performed. For asphalt mixtures the water susceptibility test according to EN 12697-12 is done on Marshall test specimens compacted by 2x25 blows. The paper presents some of the findings, including the impact of long-term ageing effects.]]></description>
      <pubDate>Mon, 27 Apr 2020 14:39:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/1697026</guid>
    </item>
    <item>
      <title>Improvement in Properties of Bitumen Using Selected Additives</title>
      <link>https://trid.trb.org/View/1697005</link>
      <description><![CDATA[The properties of bituminous binders should meet specific requirements resulting from the load in the road pavement construction. The bituminous binder is expected to have the properties to ensure the durability of the asphalt mixture, the resistance of the asphalt mixture to permanent deformations at high temperatures (elastoplastic behaviour, stiffness) and at low temperatures to sufficiently stiffness and relaxation properties to resist low temperature cracking (cohesion and tensile strength of the binder). In order to improve the qualitative properties of bitumen and/or asphalt mixtures, additives and modifiers are applied e.g. to increase elasticity, improve adhesion to aggregate, reduce viscosity, increase ageing process resistance, prevent binder drainage from the surface of aggregate, etc. In some cases, the required properties can be modified by adding “natural” bitumen. Additives to improve adhesion are surfactants that reduce surface tension at the bitumen/aggregate phase and thus improve wetting. The results of the tested additives show their positive effect on the adhesion of bitumen to the aggregate determined according EN 12697-11 after 6 and 24 hours rolling in particular on the adhesion of paving grade bitumen to acidic and neutral aggregates (granodiorite, andesite, melaphyre). However, the results show that these additives also affect basic properties of bitumen binder as penetration, softening point, viscosity. The most significant changes have been made with the use of the Licomont BS100 and Sasobit wax additives (increase in the softening point of 13 to 43 oC) which move the bitumen to the values typical for the modified bitumen. By adding CWM and Wetfix BE additives, the bitumen became softer. In most cases, the additive has reduced the bitumen viscosity, the bitumen was less viscous, that allow better workability of the mixture and the possibility of lowering the working temperatures.]]></description>
      <pubDate>Mon, 27 Apr 2020 14:39:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/1697005</guid>
    </item>
    <item>
      <title>Intrinsic adhesive and cohesive assessment of the moisture sensitivity of bio-rejuvenated recycled asphalt binders</title>
      <link>https://trid.trb.org/View/1607362</link>
      <description><![CDATA[Alternative binders not derived from fossil fuels, known as biobinders, are opening new paths for multiple applications in road infrastructure. Biobinders, usually produced from bio-oils obtained from the processing of biomass and industry by-products, are tuneable materials whose properties can be adjusted to meet specific targets. For this reason, an interesting approach is to couple biobinders with Reclaimed Asphalt (RA) by taking advantage of their rejuvenating properties to design bio-asphalt mixtures with high-content RA and no additional virgin bitumen. Recent research has proven the feasibility of this approach through validation at full-scale (BioRePavation project). However certain aspects related to the durability of bio-asphalt mixtures still require further research, one of these being their resistance to moisture damage. This study aims at filling some of these current gaps by conducting an initial investigation of the moisture sensitivity of selected biobinders and bio-rejuvenated asphalt binders. In order to do this, the intrinsic adhesion and cohesion properties of an extracted RA binder, two biobinders, their blends and two types of aggregates were characterised by means of Surface Free Energy (SFE), individually and as a system. The binders/blends-aggregate systems were further tested by means of the Pneumatic Adhesion Tensile Test Instrument (PATTI) to determine their pull-off tensile strength (POTS). The results show that the bio-rejuvenated asphalt binders present equivalent cohesive and adhesive properties to a conventional bitumen and superior performance when compared to the RA binder. Hence, the combination of biobinders and RA has great potential to guarantee resistance to moisture damage of bio-recycled asphalt mixtures with high-content RA and no additional bitumen.]]></description>
      <pubDate>Wed, 29 May 2019 17:04:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1607362</guid>
    </item>
    <item>
      <title>Moisture Sensitivity of Asphalt Mixes based on Surface Chemistry of Aggregates and Asphalt Binders</title>
      <link>https://trid.trb.org/View/1486277</link>
      <description><![CDATA[In the present study, moisture sensitivity of different aggregates-asphalt binders was evaluated using the surface free energy (SFE) approach. Three different asphalt binders, viscosity grade (VG) 30, polymer modified bitumem (PMB) 40 and crumb rubber modified bitumen (CRMB) 60, and two types of aggregates, granite and limestone, were selected in this study. The SFE components of the asphalt binders were measured using the Whilhelmy plate method, while SFE of granite and limestone aggregates were adopted from the literature. Thereafter, work of adhesion, work of cohesion, and work of debonding in the presence of water, and energy ratio (ER) were calculated to evaluate moisture sensitivity of asphalt-aggregate system. The results indicate that limestone aggregate had a higher moisture resistant potential with all types of asphalt binders compared to those of granite aggregate. Further, PMB 40 showed better bond with selected aggregate types by CRMB 60 and VG 30 asphalt binders. It was found that asphalt binder and aggregate types can have a significant influence on moisture sensitivity of aggregate-asphalt binder systems. It is expected that the present study would be a positive step in the direction of mechanistic evaluation of moisture damage potential in asphalt mixes in India.]]></description>
      <pubDate>Tue, 24 Oct 2017 09:06:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1486277</guid>
    </item>
    <item>
      <title>Quality assessment of Norwegian field trials with Warm Mix Asphalt</title>
      <link>https://trid.trb.org/View/1404646</link>
      <description><![CDATA[Eleven test sections with Warm Mix Asphalt (WMA) were constructed in four Norwegian regions in 2011. WMA is produced and laid at lower temperature than traditional asphalt concrete due to a modified mix technique or use of a temperature reducing additive. The aim of the project was to document that WMA's are of same level of quality as ordinary hot mix asphalt. The test roads sections were 1020 m in average. The trial WMA and the corresponding reference asphalt were laid in parallel lanes. Average daily traffic (ADT) of the test sections were 650 to 9000. Six WMA techniques were applied and surveyed: - WAM-foam - LMK-foam - Green asphalt (foaming and adding recycled asphalt) - Rediset WMX (chemical additive) - Cecabase RT (chemical additive) - Sasobit (organic additive). Same aggregates and gradation was used in the WMA and in the reference asphalt. The WMA-trial mixes were documented by binder testing, Marshall density, adhesion and wheel­ track rutting. In the field trials, temperature reductions of 20 to 39 °C were achieved with the WMA techniques. The WMA quality was assessed by measuring void content and wheel-tracking rutting on drilled cores from the newly laid pavement. The initial rutting and IRI-evenness of the test sections were measured with a mobile laser pavement profile scanner. The development of rutting and IRI-evenness will be measured annually. Due to differences between asphalt mixes, traffic volumes and local climates, emphasis was laid on the relative performance of the WMA and reference on each test section. There were no significant difference in quality between the new-laid WMA's and the reference asphalts. The long term performance of the test sections will be followed up.]]></description>
      <pubDate>Thu, 21 Apr 2016 12:32:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/1404646</guid>
    </item>
    <item>
      <title>Influence of various adhesion promoters on asphalt behavior by assessment of water sensitivity</title>
      <link>https://trid.trb.org/View/1404645</link>
      <description><![CDATA[Bitumen to aggregate adhesion represents one of the fundamental characteristics of asphalt mixes which are closely connected to their durability and resistance to water and frost effects. With respect to increased focus on construction cost effectiveness it is preferred to use locally available aggregate sources. These are often hydrophilic and not suitable enough to secure sufficient adhesion. Another factor is the quality of bitumen used for asphalt mixture production which bears with respect to advanced distillation processes and general business preferences of petrochemical industry another risk affecting the adhesion. Based on these assumptions different chemical adhesion promoters have been used and compared. At the same time mechanically activated microfillers based on lime and/or fly­ ashes have been used as mineral adhesion promoters or intelligent substitutes to traditional filler. Asphalt mixes of ACbin 16 or ACwear 11 type have been laboratory designed with two different types of aggregates. Indirect tensile strength has been assessed for all mixes according to EN 12697-23 with determination of water sensitivity according to EN 12697-12 and by modified test procedure described by AASHTO T-283 used in the U.S..]]></description>
      <pubDate>Thu, 21 Apr 2016 12:32:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1404645</guid>
    </item>
    <item>
      <title>Use of aggregate nanocoating to decrease moisture damage of hot mix asphalt</title>
      <link>https://trid.trb.org/View/1394708</link>
      <description><![CDATA[In this research, the effect of using nanocoating on the surface of aggregates on moisture damage of the hot mix asphalt has been studied with thermodynamic and mechanical methods. Aggregates used in this research are granite and limestone which have been modified with nano calcium carbonate (CaCO ₃ ) and nano zinc oxide (ZnO). The obtained results in this research show that tensile strength ratio of samples made with modified aggregate has improved in comparison to the control samples. Results of surface free energy indicate that coating of aggregates with nanoparticles reduces the difference between the free energy of adhesion in wet and dry conditions which reduces the stripping tendency of asphalt mixtures. Also, coating of the aggregates with nanoparticles caused better wettability of the aggregates’ surface by asphalt binder. The aggregates treated with nano CaCO ₃  showed better resistance against moisture damage in both the methods that were used in this study.]]></description>
      <pubDate>Fri, 29 Jan 2016 09:33:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/1394708</guid>
    </item>
    <item>
      <title>A fundamental adhesion model for asphalt</title>
      <link>https://trid.trb.org/View/1367600</link>
      <description><![CDATA[One of the mechanisms for the deterioration of asphalt is debonding. This is often referred to as stripping. Most losses of adhesion at the bitumen-aggregate interface are attributed to the action of water leading to a reduction in properties such as tensile strength, tensile stiffness and wear resistance. If we move to more accurate models for predicting bitumen-aggregate adhesion based on material properties, then we can be much more effective in building roads that are stable and resist hardening, crack-building, and stripping more effectively. The main aim of this doctoral thesis was to propose a hypothesis for what makes bitumen binders stay adhered to aggregates (or filler particles such as Portland cement) and to provide a fundamental understanding for the development of a new test method for bitumen-aggregate adhesion. The Hamaker constant was used to estimate van der Waals interactions. Hamaker’s constant is composed of two parts. The first part describes the Keesom and Debye contribution, which represents the attraction energy at zero-frequency, and the second part the London dispersive (electronic) contribution, which represents the attraction energy in the optical/UV spectrum. Calculations of Hamaker’s constant require accurate dielectric data, i.e. the dielectric constant and the refractive index of the interacting materials and the intervening medium. Paper I: Hamaker’s constant was introduced to describe and calculate the van der Waals interaction and to determine its relationship to resistance to stripping. Paper II: The dispersive component of minerals was calculated from their refractive indices using data from mineral data sheets. Paper III: The dispersive component of un-aged bitumen and aggregates was calculated from their refractive indices, determined by ellipsometery measurements. Paper IV: The surface force mapping technique, AFM QNM, was used to measure parameters such as topography, adhesion and elastic modulus simultaneously on un-aged 70/100 penetration grade bitumen binders. The result was presented as images representing individual and overlaid parameters, e.g. topographic images with an adhesion overlay and topographic images with a modulus overlay. The adhesion forces measured in the region surrounding (peri phase) the “bees” (catana phase) and the region in the “bee” areas are lower than the adhesion force measured in the smooth matrix (para phase). Likewise it can be observed that Young’s moduli in the region surrounding (peri phase) the “bees” (catana phase) and in the “bees” are higher than Young’s modulus of the smooth matrix (para phase). Paper V: The mechanism for bee formation was investigated via AFM. Paper VI: The bitumen components that are expected to migrate to the air interface and to the surface of laboratory glass slides (or to the surface of aggregates), were investigated based on the relative dielectric spectroscopic response of the material components, as determined by their dielectric constants and refractive indices. The total polarizability can be determined from the dielectric constant. The non-polar London dispersive (electronic) polarizability can be determined from refractive index measurements. In materials with higher permittivity at zero frequency the Keesom and Debye attraction energies will be responsible for a significant part of the polarization. Bitumen as a whole has a low degree of total polarizability. Bitumen contains a small fraction of n-heptane insoluble molecules that have a somewhat higher total polarizability and therefore may contribute to Debye and Keesom interactions. Bitumen as a whole is highly London dispersive (electronic) polarizable and the asphaltene (or n-heptane insoluble) fraction is even higher London dispersive (electronic) polarizable. The degree of non-polar London dispersion polarizability increases with increasing molecular size and with increasing aromaticity. Paper VII: Adhesion properties of un-aged 70/100 penetration grade bitumen binders were probed by means of permittivity analysis. The initial adhesion of non-aged bitumen binders to pure quartz aggregates is primarily London dispersive due to low total polarizability of the components. The higher surface coverage with the addition of the Portland cement to the surface of the aggregates can be explained by the addition of components with higher London dispersive polarizability and higher total polarizability of CaO, MgO and ironoxides. Portland cement is a material contributing to Debye and Keesom interactions. Portland cement could also have chemical influence on its bonding to aggregates. A strong correlation was identified between the average tangent of the dielectric loss angle in the frequency region of 0.01 to 1 Hz and surface coverage (a common method to indicate suitability of bitumen for use in roads). Surface coverage is higher for bitumen binders having a larger average loss tangent. It is suggested that the average tangent of the dielectric loss angle in the frequency range of 0.01 to 1 Hz, could be used as an indicator for predicting polarizability and thereby, adhesion potential of bitumen binders.]]></description>
      <pubDate>Tue, 01 Sep 2015 11:17:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/1367600</guid>
    </item>
    <item>
      <title>Evaluation of Polyaminoamide As a Surfactant Additive in Hot Mix Asphalt</title>
      <link>https://trid.trb.org/View/1366411</link>
      <description><![CDATA[The phenomenon of breaking the bond between the aggregates and the bitumen is known as stripping. The stripping of asphalt films from the surface of aggregate particles results in premature failure of asphalt pavement. This causes weakening of pavement resistance to rutting and fatigue. Furthermore, moisture damage increases the susceptibility of pavement to reveling, a distress that causes the loss of skid resistance on surface of the road and deterioration of pavement. Surfactant additive or adhesive agent is a surface-active agent that changes (lowers) the surface tension of rock materials. Introduction of surfactant additive results in increased strength of adhesive bond between bitumen and the rock materials surface preventing stripping throughout the service life of the asphalt concrete. Polyaminoamide is an organic water soluble compound that allows waterproofing mineral aggregate surfaces and acts as a bonding agent to bitumen. The objective of this research is to study the effect of polyaminoamide based and pholiphosphoric acid based liquid additives on stripping, moisture susceptibility, rutting and fatigue performance of asphalt concrete. In this paper, boiling water test was used to determine the percentage of stripped aggregates after boiling. The moisture susceptibility of asphalt mixtures was investigated by means of testing the retained indirect tensile strength after water immersion using Marshal stability test method. Wheel tracking test was also conducted on asphalt slabs prepared in the laboratory to determine rut resistance. Asphalt concrete with commonly used mineral filler was chosen as a control mixture. It was found that the adhesion additive not only improves stripping resistance, but also slightly improves asphalt rut resistance.]]></description>
      <pubDate>Mon, 24 Aug 2015 14:12:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1366411</guid>
    </item>
  </channel>
</rss>