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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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      <title>Assessment of PAH Concentrations and Toxicity of Runoff from Sealed Asphalt Surfaces</title>
      <link>https://trid.trb.org/View/2271510</link>
      <description><![CDATA[Owners often apply asphalt sealants to parking lots and driveways to enhance appearance and protect the surface. There are two sealant types generally used in the United States today: asphalt emulsion and coal tar emulsion. Coal tar is a suspected human carcinogen and is detrimental to the health of a variety of organisms. Runoff from these surfaces may be a significant source of polycyclic aromatic hydrocarbons (PAHs) to the environment. The results from a field study of PAH concentrations and potential toxicity of runoff from asphalt surfaces sealed with coal tar sealant and asphalt emulsion sealant will be presented. The study assessed exposure concentrations and evaluated the short-term effects of leached PAHs on potential toxicity to receiving waters. The field study was conducted on an actively-used asphalt parking lot at EPA's Urban Watershed Research Facility (UWRF) in Edison, NJ. The lot was divided into three test plots: one sealed with coal tar sealant, one coated with asphalt emulsion sealant, and an unsealed control. Collected rainwater was homogenized and delivered to the plots for each test. Samples were collected immediately after running off the asphalt, as well as after mixing downstream at the end of a common trench drain. This was done in order to compare runoff from sealed asphalt surfaces to that which has been mixed and transported downstream. Samples were analyzed for a suite of PAHs, toxicity via the Microtox method, and water quality parameters including: solids, total organic carbon, and chemical oxygen demand. Both the runoff from the sealed surfaces and the coatings themselves were tested for toxicity using the Microtox light output procedure.]]></description>
      <pubDate>Fri, 22 Dec 2023 08:46:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/2271510</guid>
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      <title>Application of phenol-cresol-formaldehyde resin as an adhesion promoter for bitumen and asphalt concrete</title>
      <link>https://trid.trb.org/View/1892817</link>
      <description><![CDATA[In this study, the phenol-cresol-formaldehyde (PhCR-F) resin was synthesised from the phenolic fraction of coal tar resin and formaldehyde through polycondensation. The physico-mechanical properties of the asphalt concrete were subsequently characterised to examine its water saturation, coefficient of long-term water-resistance (after 15 and 30 days), and compressive strength (at 20°C and 50°C). The results revealed that the addition of PhCR-F markedly increased the adhesion index with the surface of granite aggregates and glass before and after heating the bitumen. Furthermore, the PhCR-F addition enhanced the bitumen softening point, long-term water resistance, and thermo-stability but decreased the water-saturation index along with the penetration and ductility of bitumen. In conclusion, the study findings revealed that the synthesised PhCR-F resin is a promising adhesion promoter in pavement grade oil bitumen for application with asphalt concrete.]]></description>
      <pubDate>Tue, 07 Dec 2021 13:03:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/1892817</guid>
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      <title>Oils and Tars from Iowa Shales</title>
      <link>https://trid.trb.org/View/1366820</link>
      <description><![CDATA[The inadequate supply of suitable road surfacing material in the  southern part of Iowa raises the question of the possibility of utilizing  certain shales abundant in this area. These carbonaceous shales commonly  overlie the coal beds and may also be found as impurities in the coal seams.  They constitute the "slate" which with minor amounts of coal makes up the  "gob" piles at the mines. These shales frequently contain enough carbonaceous  material to burn. Those which do not usually require only a relatively small  amount of coal mixed with them to support combustion. As a result, the  "gob" piles frequently burn. The residual shale material is frequently  used locally as a road surfacing material. However, since there is no  control over the burning, there is no assurance that the product is the most  suitable which might be produced or that it is even uniform in its properties.  To determine if a controlled burning would produce a suitable road  building product economically a research project "Use of Shales as Highway  Materials" (ISHC Project HR-21, IEES Project 299-S) was set up in the Iowa  Engineering Experiment Station with funds provided by the Iowa State Highway  Commission, This project was supervised by Charles Frush, formerly  Assistant Professor of Mining Engineering at Iowa State University. The  various shales were subjected to controlled burning, and the solid residues  were tested for their suitability for highway use.]]></description>
      <pubDate>Mon, 31 Aug 2015 09:10:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1366820</guid>
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      <title>Study on the Application of Coal Tar Pitch in Middle Asphalt Layer of Shanxi Highway Project</title>
      <link>https://trid.trb.org/View/1275539</link>
      <description><![CDATA[In this study, the objective was dedicated to the application of coal tar pitch in road engineering construction. The present application situation of the coal pitch was discussed. The asphalt and the asphalt mix were designed. Appropriate adjustment of the proportion of coal pitch and petroleum asphalt improved the technical indexes of asphalt. The optimal bitumen-aggregate ratio based on the closest skeleton-interlocking dense condition principle is selected. Results indicated that the mix with modified coal tar pitch and the designed optimal bitumen-aggregate ratio had good performance, involving high temperature stability, low temperature cracking resistance and water stability. It was also found that the construction temperature can be reduced by the warm mix asphalt additive, decreasing the volatile of polycyclic aromatic hydrocarbon which was a carcinogenic substance in coal pitch. The conclusion of this paper is valuable for the further application of coal tar pitch.]]></description>
      <pubDate>Mon, 12 May 2014 13:08:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/1275539</guid>
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    <item>
      <title>Randle Reef Sediment Remediation Project</title>
      <link>https://trid.trb.org/View/1302810</link>
      <description><![CDATA[The Randle Reef site is the largest coal tar-contaminated sediment site in the Great Lakes. This paper presents a summary of the design for the Randle Reef Remediation Project, which involves dredging 500,000 cubic meters (654,000 cubic yards) of sediment and construction of a 7.5-hectare (18.5-acre) Engineered Containment Facility (ECF) for containment of the dredged material. Contaminants of concern are polycyclic aromatic hydrocarbons (PAHs), as well as metals and coal-tar nonaqueous-phase liquid (NAPL). The ECF will serve to isolate contaminated sediment beneath the containment facility and dredged from the Harbour and will provide new land for a near-shore island terminal and provide berths for deep draft vessels. A multi-layer cap will be constructed over the dredged material placed in the ECF. The remediation project includes many design elements which are summarized in this paper. Construction is anticipated to begin in 2014/15.]]></description>
      <pubDate>Fri, 25 Apr 2014 12:04:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1302810</guid>
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    <item>
      <title>New Studies Defend Use of Refined Tar-Based Sealers</title>
      <link>https://trid.trb.org/View/1098798</link>
      <description><![CDATA[This article reports on studies sponsored by the Pavement Coatings Technology Council (PCTC) that have concluded that refined tar-based sealants are not the main source of polycyclic aromatic hydrocarbons (PAH's) in the environment.  The findings from the PCTC studies refute the findings of 2005 studies conducted in Austin, Texas, which showed that refined tar-based sealant contain PAHs and that soil or sediment samples taken next to a sealed parking lot sometimes contain high levels of PAHs. This proposed link between the PAHs in refined tar-based sealant and PAHs in rivers, streams, and lakes has resulted in regulatory challenges and bans of sealers in some locations. The city of Austin banned the use of refined tar-based sealant as of January 1, 2006. The PCTC study examined sediment samples collected from Austin's streams before the ban in October 2005, and again after the ban in April 2008. Findings showed that total concentrations of PAHs in sediments before and after the ban did not change.   If sealers were the principal source of PAHs in sediments, then PAH concentrations should have declined once the ban was in place. PAHs in the Austin samples were also evaluated using environmental forensics techniques. PAH fingerprinting of sediments collected before and after the ban did not identify any marked changes. When all the data available in Austin is considered, it appears that refined tar-based sealant is not a major source of PAH in sediments downstream of the immediate area of a sealcoated lot.   Although PAHs are found in sealers, they can also be found in used motor oil, grilled meats and vegetables, exhaust from internal combustion engines, products made from coal and petroleum, and emissions from fossil fuel power plants and forest fires.]]></description>
      <pubDate>Mon, 18 Apr 2011 12:25:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/1098798</guid>
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    <item>
      <title>Defending Refined Coal Tar-Based Sealer</title>
      <link>https://trid.trb.org/View/924333</link>
      <description><![CDATA[Several recent studies have attempted to link refined coal tar-based sealer to possible cancer-causing compounds. The latest study attempts to link refined coal tar-based sealer to concentrations of polycyclic aromatic hydrocarbons (PAHs) in dust collected from ground floor apartments in Austin, Texas.  A similar earlier study led to a ban of refined coal tar-based sealer in Austin, Texas in 1996.  This article describes how the sealcoating industry is mounting a multi-pronged defense of the coal tar-based sealer.  The Pavement Coatings Technology Council (PCTC) has hired a specialist who will analyze the new Austin study and a related Canadian Settled Dust Study and report back in March about the studies' process, results, and conclusions. In addition, a PCTC follow-up study that refutes the 2005 Austin study is in the final stages of the scientific review process.  The sealcoating industry argues that PAHs are in many other sources other than just sealers, and have not be shown to be a known human carcinogen.  The industry maintains that they have safely used this product for 60 years and have no reason to think there are any adverse effects when used according to manufacturers recommended specifications.]]></description>
      <pubDate>Tue, 27 Jul 2010 07:30:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/924333</guid>
    </item>
    <item>
      <title>Recycling of Tar Decanter Sludge through the Addition of Coke Oven Batteries in Charge Coal Feed</title>
      <link>https://trid.trb.org/View/898911</link>
      <description><![CDATA[This paper describes how toxic tar decanter sludge previously dumped at the Bokaro Steel Plant, Steel Authority of India Limited (SAIL), is now being recycled to the coke ovens via the coal charge. Not only has an environmental pollutant been removed but a savings of US $ 0. 15 million a year has resulted due to carbon recovery. Based on encouraging results at Bokaro, other SAIL plants have undertaken the implementation of the system. This paper depicts details of the generation of tar decanter sludge, the modified recycling system, the design features, the novelty in the system, the modifications, and the economic benefits.]]></description>
      <pubDate>Wed, 19 Aug 2009 13:50:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/898911</guid>
    </item>
    <item>
      <title>Variety Allows Contractors to Meet Specific Sealcoating Needs</title>
      <link>https://trid.trb.org/View/841902</link>
      <description><![CDATA[Sealcoating equipment comes in several sizes and with a variety of features.  This article describes sealcoating equipment from 9 manufacturers, highlighting the features and benefits of each unit.  Units range in size from 300 to 2000 gallons.  Some are skid- or truck-mounted while some are ride-on.  The most important factors to consider when purchasing a sealcoating unit are the size and type of the contractor's jobs.  The type of sealer material, asphalt or coal tar, can also be an important consideration.]]></description>
      <pubDate>Tue, 18 Dec 2007 11:28:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/841902</guid>
    </item>
    <item>
      <title>Guidelines on the Use of Fog Seals and Rejuvenator Seals</title>
      <link>https://trid.trb.org/View/836887</link>
      <description><![CDATA[These guidelines derive from Texas Department of Transportation (TxDOT) Project 0-5091 and Report 0-5091-3.  Replicate cores of both treated and untreated highway and general aviation pavement sections were analyzed in this extensive study.  Whole cores were assessed by water permeability and by susceptibility to permanent deformation.  Replicate cores were sawed into approximately one-quarter-inch slices that were individually analyzed for total air voids, accessible (or interconnected) air voids, binder content, oxidative aging and rheology, and the presence of fog seal material.  The fog seal materials used in this project were emulsions of asphalt materials and coal tar type materials typically used by TxDOT.  A table is presented summarizing:  treatment material, example grades, solvent, application rate, residual viscosity, field performance (advantage and disadvantage), and remarks.]]></description>
      <pubDate>Wed, 10 Oct 2007 15:52:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/836887</guid>
    </item>
    <item>
      <title>Material Properties of Coal-Tar Emulsion Sealers</title>
      <link>https://trid.trb.org/View/808942</link>
      <description><![CDATA[Coal-tar emulsion sealers are used to protect hot-mix asphalt pavements from damage due to the spillage of petroleum-based materials. This paper contains the results of a study, which has field tests and laboratory tests, concerning the effect of various amounts of aggregate, temperature variations, a polymer additive, and aging on the material properties of coal-tar emulsion mixtures. The material properties tests included thermal expansion, creep stiffness test, and by measuring tensile strength, the stress-strain relationships. The study results indicate that the thermal expansion of the mixtures increased with increasing amounts of coal-tar emulsion; however, this effect was slightly reduced with the addition of a polymer additive. Creep stiffness values increased with age and increasing amounts of aggregate in the mixture. The results of the stress-strain evaluation were not consistent. Increased amounts of aggregate, lower temperatures, and decreased amounts of polymer generally resulted in greater stress levels being achieved prior to failure.]]></description>
      <pubDate>Fri, 25 May 2007 10:36:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/808942</guid>
    </item>
    <item>
      <title>Understanding Sealer Options</title>
      <link>https://trid.trb.org/View/807073</link>
      <description><![CDATA[Although refined coal tar sealer has been the most popular pavement sealer in the past, limited availability is forcing contractors to explore alternative products.  This article describes some of the available sealers.  Asphalt emulsion sealers are the primary alternative to coal tar, but these sealers perform very differently than refined coal tar sealers and there currently are no industry specifications for asphalt-based sealers.  Asphalt-based sealers can vary substantially from producer to producer and even from batch to batch in terms of physical properties and chemical composition.  Contractors and producers both generally consider asphalt-based sealers to be inferior to coal tar sealers in terms of durability, drying time and consistency.  Products that blend asphalt and coal tar also are available.  The handling and use of these products is determined by which product dominates the blend.  A blend that is predominately coal tar may be a useful way of extending the limited supply of that product.  Blended sealers generally take longer to cure than either 100% asphalt or 100% coal tar products.  Some producers refuse to make blended products because they feel that the two products are chemically incompatible.  A few producers are using ceramics with asphalt material to produce what could be a new and stronger pavement sealer.  This sealer has the same characteristics as coal tar, but without its drawbacks.  Set and cure times generally are quicker than coal tar and the cost is comparable to that of asphalt sealers.]]></description>
      <pubDate>Fri, 25 May 2007 10:34:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/807073</guid>
    </item>
    <item>
      <title>Blinded by "Science"</title>
      <link>https://trid.trb.org/View/805655</link>
      <description><![CDATA[The city of Austin, Texas banned the use of coal tar pavement sealers in 2005.  This article discusses this ordinance and whether there is scientific evidence to justify the ban.  The Austin city council banned the coal tar-based products due to the belief that coal tar sealants are a major source of polycyclic aromatic hydrocarbons (PAHs), an organic contaminant that is carcinogenic and toxic to aquatic life.  This ban was based primarily on a study by the U.S. Geological Survey that suggested that runoff with the sealant is contaminating the city's streams.  However, the seal coating industry has challenged the objectivity and data quality of this study.  Other research has suggested that coal tar sealants are not a major contributor to PAH contamination.  A new study, which relies on both scientific principles and input from a variety of organizations, is currently underway.]]></description>
      <pubDate>Wed, 25 Apr 2007 13:45:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/805655</guid>
    </item>
    <item>
      <title>What Happened to Coal Tar in 2006?</title>
      <link>https://trid.trb.org/View/805056</link>
      <description><![CDATA[Crude tar had been an important component of sealcoating for the last 50 years.  However, there have been problems with availability of crude tar in recent years, which has resulted in shortages or delivery delays of refined coal tar sealer.  This article discusses the availability issues that plagued refined tar producers, sealer producers and sealcoating contractors in 2006 and earlier, and tries to predict what may happen in the future.  Production of coal tar has decreased in the last decade due to strikes, plant closings and production cutbacks.  In addition, most coal tar is sold to the aluminum industry, which is a growing market, further reducing the sealcoating market's share.  Sealcoating supply companies are reacting by distributing coal tar to their contractor customers on an as-needed basis, increasing production of asphalt/coal tar blends, and increasing production and marketing of asphalt-based sealers.  There are few indications that supplies of refined coal tar will improve in 2007.]]></description>
      <pubDate>Fri, 30 Mar 2007 06:58:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/805056</guid>
    </item>
    <item>
      <title>Performance Evaluation of Jet Fuel Resistant Polymer-Modified Asphalt for Airport Pavements</title>
      <link>https://trid.trb.org/View/794274</link>
      <description><![CDATA[Polymer-Modified Asphalt (PMA) is often applied at airports to improve the performance of Hot Mix Asphalt (HMA) pavements with respect to permanent deformation and cracking.  Unfortunately, spillage of jet fuel softens the commonly used PMA’s, resulting in a decrease of the integrity of the asphalt.  Coal tar sealers, which are known to be carcinogenic, are often applied to prevent jet fuel damage.  The application of these sealers has two drawbacks; the seal coatings crack, which allows fuel to damage the HMA pavement and their use places carcinogenic material onto a pavement that may be recycled.  In laboratory tests, jet fuel resistance has been measured by loss of material from a pavement sample after 24 hours immersion in jet fuel.  Requirements of a maximum one percent weight loss after 24 hour immersion have been used to qualify an asphalt as jet fuel resistant.  Standard unmodified and modified asphalts fail to meet this criteria.  In 1995 Ooms Avenhorn Holding, The Netherlands, developed a coal tar free, polymer-modified jet fuel resistant PMA (PMA JR) for use at the Kuala Lumpur Aitport.  Since that time PMA JR has been evaluated in various laboratory studies and used at airports around the world.  This asphalt exhibits the excellent mechanical properties of a PMA and meets the jet fuel resistant requirements as defined by the immersion test.  The material was introduced into the United States in 2002 at La Guardia Airport and in 2004 at Logan Airport.  This presentation will discuss these laboratory studies as well as field experiences with this asphalt.]]></description>
      <pubDate>Fri, 01 Dec 2006 08:10:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/794274</guid>
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