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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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    <item>
      <title>Mix design procedure for foamed asphalt mixtures</title>
      <link>https://trid.trb.org/View/1425390</link>
      <description><![CDATA[Mechanical foaming is the most popular method for producing warm mix asphalt in the United States; yet, a standard mix design procedure for foamed asphalt mixtures has not been established. Currently, the design of foamed asphalt mixtures consists of determining the optimum binder content by following a standard hot mix asphalt (HMA) design procedure and then estimating the foaming water content based on the foamer manufacturer's recommendation, engineering judgement, or previous experience. This practice fails to account for the effect of foaming on binder and mixture properties, and therefore may not ensure desirable foamed mixture performance. To overcome this shortcoming, additions to the standard mix design procedure were proposed in this study in order to accommodate foamed asphalt mixtures, which included optimisation of foaming water content and evaluation of foamed mixture performance. In addition, the proposed procedure was verified using materials procured from two field projects. The optimum foaming water content (W<sub>opt<sub>%) was first determined by comparing the workability results of foamed mixtures at various foaming water contents. Afterwards, the foamed mixture at W<sub>opt<sub>% was tested for coatability and performance evaluation, and all laboratory test parameters complied with established American Association of State Highway and Transportation Officials or agency specifications or were equivalent to or better than the control HMA test results. Therefore, the proposed foamed mix design procedure seemed a viable alternative for designing foamed mixtures with adequate pavement performance.]]></description>
      <pubDate>Fri, 21 Oct 2016 16:32:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/1425390</guid>
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    <item>
      <title>The Guayule Plant: A Renewable, Domestic Source of Binder Materials for Flexible Pavement Mixtures</title>
      <link>https://trid.trb.org/View/1339618</link>
      <description><![CDATA[The guayule (pronounced 'why-YOU-lee') plant grows in arid and semi-arid regions (e.g. the southwestern U.S.) and is a source of natural rubber. It was cultivated and processed during the World War II rubber shortage and is currently being processed primarily for the manufacture of hypo-allergenic latex (e.g. medical gloves, personal hygiene products). Depending on the process, many materials can be extracted from guayule. However, there are three basic products: rubber, resin, and bagasse. The rubber and resin (biopolymers) are of particular interest as they could prove to be renewable binder materials for flexible pavement mixtures. Limited preliminary testing showed that the resin could potentially be used as a recycling agent (viscosity modifier) when designing flexible pavement mixtures with a high percentage of reclaimed asphalt pavement (RAP), a small percentage of processed roofing shingles, and some virgin aggregate. The concept is to design a flexible pavement mixture produced with little to no virgin petroleum-based material. Due to the rising price of crude oil, flexible pavement costs have increased significantly. In regard to the concept, the potential impact on highway construction could be lower costs. A thorough experimental program is necessary to assess the limits of the use of the guayule rubber and resin in the context of this concept. Additionally, the guayule processing industry could benefit through the opening of another market for its products. Maybe more importantly, national security could be enhanced by decreasing the dependence on foreign oil.]]></description>
      <pubDate>Wed, 31 Dec 2014 01:00:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1339618</guid>
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    <item>
      <title>Simulating the Effects of Instrumentation on Measured Pavement Response</title>
      <link>https://trid.trb.org/View/1218077</link>
      <description><![CDATA[Asphalt strain gauge installation procedures have typically used hot mix sieved through a 4.75 mm screen, hand placed over the gauges and hand compacted prior to roller compaction which has led to  a high gauge survival rate. This finer mix in the immediate vicinity of the gauge could theoretically yield lower moduli and higher strains. The objective of this study was to evaluate the potential effect of using a finer mix as gauge cover on pavement response. Finite element analysis was used to simulate a three-layered pavement structure containing a patch of sieved material at the bottom of the asphalt concrete layer. Tensile strain responses were calculated at the bottom of the asphalt concrete layer under a single load for all structures with and without the finer mixture. The results were compared to a previously defined benchmark of 30 µε which was more likely tobe exceeded with layers thinner than 5 in. and moduli between 200 and 500 ksi.]]></description>
      <pubDate>Fri, 07 Dec 2012 09:58:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1218077</guid>
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      <title>Evaluation of Long-Term Environmental and Functional Performance of Innovative Photocatalytic Road Pavements</title>
      <link>https://trid.trb.org/View/1091916</link>
      <description><![CDATA[Air pollution represents a serious and inevitable challenge. In recent years lots of researchers spent time and resources to find solutions and, consequently, some important advances have been made, leading to stronger environmental policies, hinging not only on regulation of specific sources and fuel quality, but also on the reduction of pollutants concentration near the source. Particular attention was devoted to development of innovative photocatalytic road pavements. This paper concerns road pavements able to reduce the gas exhausted from vehicles, thanks to the action of photocatalysts, mainly titanium dioxide, incorporated into the pavement mixture. The experimentation carried out allowed to evaluate the depolluting action due to a photocatalytic mortar as well as mechanical characteristics of the pavement. Results allowed also to find the optimal water and titainium dioxide content for the photocatalytic mortar. Furthermore a new developed bituminous photocatalytic pavement was analyzed, focusing on long term environmental pavement effectiveness, measured with a new procedure able to simulate vehicles wearing effect on surface pavements, obtaining excellent air pollutants concentration reduction and demonstrating the significantly enhancement of air quality given by photocatalytic road materials.  Air pollution improvement was accurately quantified with a newly equipment that enabled the evaluation of Nitrogen Oxides reduction and allowed to investigate the factors affecting photocatalytic performances.]]></description>
      <pubDate>Mon, 21 Mar 2011 14:13:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1091916</guid>
    </item>
    <item>
      <title>Evaluation of Coarse Aggregate Quality with Respect to Current Specifications for Pavement Mixtures</title>
      <link>https://trid.trb.org/View/1089699</link>
      <description><![CDATA[In many states, coarse aggregate specifications for pavement mixtures are outdated and do not reflect the current level of knowledge concerning desirable aggregate properties for pavement applications. Because the performance of pavements is highly dependent on the quality of aggregate used within them, the quality of the aggregate must be evaluated based on the consistency of desirable aggregate properties. The primary objective of this research was to evaluate the compliance and consistency of coarse aggregate properties with respect to current specification requirements. To evaluate compliance and consistency, testing data from local sources in the state of Minnesota were compared to regional and national records on aggregate quality and specification requirements. Percent within limit calculations were conducted to evaluate the compliance of aggregate properties with respect to the current quality requirements of abrasion resistance, soundness, and percent spalling material. The results of the study demonstrated that aggregates complied very well with current specifications. However, when evaluating the variability of test results, inconsistency between different sources was noticeable even though quality requirements were easily met by tolerance criteria. This study emphasizes the inconsistency of aggregate properties among sources subjected to the same (or similar) specification requirements.]]></description>
      <pubDate>Wed, 16 Feb 2011 13:42:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1089699</guid>
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    <item>
      <title>Effect of Different Dosages of Polypropylene Fibers in Thin Whitetopping Concrete Pavements</title>
      <link>https://trid.trb.org/View/848476</link>
      <description><![CDATA[This study was a collaborative effort between the Arizona Department of Transportation (ADOT), Arizona State University (ASU), and the local concrete industry to evaluate the effect and potential performance of Polypropylene Fiber Reinforced Thin Whitetopping pavement sections in Arizona.  A laboratory experimental program was undertaken to evaluate the engineering properties for four different mixtures: a control mix with no fibers, and mixes with Polypropylene fibers using the following dosages: 3, 5 and 8 lb/cy. Various samples were collected during construction and tested for compression, flexural, and toughness using cylindrical, prismatic and round panel specimens.   While the compression results did not show any added benefit with the addition of polypropylene fibers, the analysis of flexural and round panel tests demonstrated the advantage of the fibers. Specifically, the toughness results from both tests showed an increase in these values when the percentage of fibers was increased.  However, the results of toughness can not be taken into account using common concrete pavement design methodologies, since the traditional input value is the modulus of rupture. Therefore, an analysis approach was performed that take into account the additional benefit of the polypropylene fibers by adding a residual strength to the modulus of rupture.  	It was concluded that the effect of the addition of fibers was best captured using the round panel test. The percentage increase in toughness values from the different fiber dosages was larger in the round panel test than the flexural test. It was also concluded that the use of 5lb/cy fiber dosage has the best value-added benefit to the mix.]]></description>
      <pubDate>Mon, 25 Feb 2008 14:32:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/848476</guid>
    </item>
    <item>
      <title>Investigation of Short- and Long-Term Variations of Pavement Surface Characteristics at the Virginia Smart Road</title>
      <link>https://trid.trb.org/View/802383</link>
      <description><![CDATA[Analysis of the frictional properties of the tire-pavement interface provides useful information to minimize wet-weather accidents and aid state agencies in making better pavement management decisions.  In this paper, the surface friction and texture properties of 12 asphalt pavement sections placed at the Virginia Smart Road pavement facility were studied over a 6-year time period.  The surfaces investigated include five SuperPaveTM mixes, an Open-Grade Friction Course (OGFC) and a Stone Matrix Asphalt (SMA) mix.  The levels of friction and macrotexture of these pavement sections were compared and analyzed.  Short-term (seasonal) and long-term (multi-year) variations of the surface characteristics were investigated in order to learn how the properties vary with temperature and time, which can be used to support asphalt mixture selection, determine the need for friction correction factors, and assess their suitability for use on the network pavement monitoring.   The investigation confirmed that the environmental factors have a significant effect on the seasonal variation of friction.  For all mixture types investigated, the friction measurements experienced variation within a year (short-term) and throughout several years (long-term).  Both the friction number at zero speed [FN(0)] and percent normalized gradient (PNG) decrease in the summer and thus friction varies differently at low and high speeds.  In the long term, the low-speed friction increases first due to weathering of the asphalt film from the aggregate, and then starts to decrease, probably due to polishing and weathering.  Macrotexture variations are almost unnoticeable within a year and small across 5 years.  The measured texture depth initially decreases a little, and then starts a modest ascending trend.  This is probably due to the loss of fines through weathering and/or washing by the rainfall.]]></description>
      <pubDate>Tue, 10 Apr 2007 09:22:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/802383</guid>
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    <item>
      <title>Mechanical Properties of Concrete Pavement Mixtures with Larger Size Coarse Aggregate</title>
      <link>https://trid.trb.org/View/794283</link>
      <description><![CDATA[The use of larger maximum size aggregates (MSA) in concrete mixtures can increase the load transfer efficiency across aggregate interlock joints if small crack widths are achieved. Aggregate interlock joints can minimize the number of dowels required on  airport and low volume concrete pavements, and thus decrease their total construction cost. This paper describes a laboratory study evaluating the strength, fracture, and shrinkage properties of airport concrete mixtures with 1 and 1.5 inch MSA and several total cementitious contents. Although the split tensile and flexural strength of the larger MSA mixtures were reduced by 20 percent, the 28-day fracture energy was similar between the mixtures. The 1-day GF was significantly greater for the larger MSA mixture indicating a greater joint shear transfer capability. The brittleness of the concrete was also reduced as the MSA increased. Finally, the concrete free shrinkage was similar for the same mix proportions but different MSA.]]></description>
      <pubDate>Fri, 01 Dec 2006 08:10:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/794283</guid>
    </item>
    <item>
      <title>TAKING CONCRETE TO THE NEXT LEVEL</title>
      <link>https://trid.trb.org/View/725799</link>
      <description><![CDATA[Two elements contribute to concrete performance and the service life of pavements--the concrete mixture itself and construction practices engineers use to mix, place, and cure the concrete. The ideal mixture combined with bad practices can produce an inferior result with problems such as cracking, poor concrete durability, and premature deterioration. Similarly, a poor mixture coupled with good practices also can produce a substandard result. This article discusses efforts by the Federal Highway Administration's Portland Cement Concrete Pavement team at the Turner-Fairbank Highway Research Center in McLean, Virginia, to study various aspects of concrete performance, including fresh and hardened concrete properties. The aim is to provide research on concrete improvement, through better material selection and proportioning, and on improvement of lab and field test performance predictions.]]></description>
      <pubDate>Wed, 04 Sep 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/725799</guid>
    </item>
    <item>
      <title>OPEN-GRADED EMULSION MIXTURES: 25 YEARS OF EXPERIENCE</title>
      <link>https://trid.trb.org/View/507763</link>
      <description><![CDATA[Open graded emulsion mixtures (OGEM) have been used extensively as road surfaces in the Pacific Northwest since 1966.  The mixtures consist of open-graded aggregate (20x6 mm) and 5 to 7% of a cationic mixing graded emulsion (CMS-2 or CMS-2h).  This paper presents the results of several agency experiences that indicate that OGEM usually performs as well or better than conventional dense-graded asphalt concrete in most applications. It also includes mix properties (modulus, changes in gradation with time, etc.) to illustrate that conventional test procedures during this period as well as guidelines are not appropriate for evaluating this product.  The paper includes layer equivalencies which have evolved during this period as well as guidelines for use of OGEM.  Over 16,000 km of road have been surfaced with OGEM during this period.]]></description>
      <pubDate>Sun, 17 Oct 1999 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/507763</guid>
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