Asphalt SHRP Reports

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Asphalt: A Strategic Plan--1990Discusses the objectives and planned products of the asphalt program area as of 1990, including performance-based specifications for asphalt binders and asphalt-aggregate mixtures. Describes numerous secondary research products. 56 pages. SHRP-A-301

Summary Report on the Aging of Asphalt-Aggregate Systems A literature study of the aging phenomenon in asphalt- aggregate mixtures. This report identifies aging procedures that show promise for development as performance-related accelerated aging tests. 100 pages.SHRP-A-305

Summary Report on Low Temperature and Thermal Fatigue CrackingPresents the results of a literature review and analyzes responses to a survey questionnaire sent to state departments of transportation. Eight performance-related test systems and methods are evaluated. 83 pages. SHRP-A-306

Hypotheses and Models Employed in the SHRP Asphalt Research ProgramUpdates the information presented in Asphalt: A Strategic Plan-1990. 64 pages.SHRP-A-311

Summary Report on Fatigue Response of Asphalt MixturesResearchers evaluated current test methods and procedures for measuring the fatigue response of asphalt paving mixtures. Factors influencing fatigue response, including specimen fabrication, mode of loading, mixture variables, and loading and environmental variables are also discussed. 147 pages. SHRP-A-312

A Literature Review of the Adsorption of Asphalt Functionalities on Aggregate SurfacesExamines the current state of knowledge of the theoretical and technical aspects of adsorption and how adsorption of polar functionalities influences the chemistry of the asphalt-aggregate interface. 34 pages.SHRP-A-313

Asphalt Properties and Relationship to Pavement Performance: Literature ReviewA summary and analysis of information in technical literature that relates chemical and physical asphalt properties to pavement performance. 413 pages. SHRP-A-314

Summary Report on Permanent Deformation in Asphalt ConcreteExamines information concerning permanent deformation characteristics of asphalt-aggregate mixtures. 120 pages. SHRP-A-318

Binder Characterization and Evaluation by Nuclear MagneticResonance SpectroscopyEight asphalt cements were studied in solution-state and solid-state experiments to obtain information about: the amounts of aromatic carbon in an average asphalt molecule; how carbon is arranged in terms of the size of the aromatic system and the extent of substitution; arrangement and number of alicyclic rings, aliphatic chain length, and the extent of branching. All these data and more show both surprising similarities and significant differences among the asphalts studied. 1 42 pages. SHRP-A-335

Fundamental Properties of Asphalt-Aggregate Interactions Including Adhesion and AbsorptionThe results of research on the chemistry and physics of the asphalt-aggregate bond include: models of adhesion and stripping; a net adsorption test for a quick and reliable method to measure both the affinity and water sensitivity of a given asphalt-aggregate pair; and tests addressing specific problems involving asphalt-aggregate interactions such as the limestone reactivity test. Includes studies of the impact of water and aging on adhesion. 605 pages. SHRP-A-341

Development and Validation of Performance Prediction Models and Specifications for Asphalt Binders and Paving MixesResearchers developed a model to predict the amount of fatigue cracking, thermal cracking, and rutting in asphalt concrete pavements over time, using results from the accelerated laboratory tests. The model uses detailed environmental data and can determine the optimal mixture design for specific conditions. The pavement performance models for each distress also were used to confirm the relevant binder and mixture properties established by other SHRP contractors using accelerated laboratory tests and laboratory torture tests; and to establish the degree of correlation between those asphalt binder and mixture properties. Results from these model studies were used to confirm or make recommendations for revisions to the asphalt binder specification. 518 pages. SHRP-A-357

Binder Characterization and Evaluation--Volume 1 Investigates the chemical and physical properties of petroleum asphalts used in the construction of highway pavements. The chemical studies' objective was to measure and understand the interactions among molecular species that contribute to behavior associated with high molecular weights, which explains the rheological behavior of asphalt. The characterization of rheological behavior was emphasized in the measurement of physical properties. A self-consistent description of petroleum asphalt has been used to develop predictions of asphalt performance in pavements. The model and predictive capability constitute the major portion of Volume 1. 152 pages.SHRP-A-367

Binder Characterization and Evaluation--Volume 2: ChemistryDescribes the experimental results from the chemical composition studies. Analytical methods such as streamlined preparative size exclusion chromatography, supercritical fluid chromatography, and potentiometric titration were adapted for asphalt component analysis. As a result of these separations, asphalt rheological properties were rationalized by chemical parameters such as molecular weight, molecular size distribution, and polarity factors. Asphalt oxidation studies indicate that the oxidative aging at service temperatures does not follow the classical radical-chain. 479 pages.SHRP-A-368

Binder Characterization and Evaluation--Volume 3: Physical CharacterizationPresents new test methods and models for test procedures for aging and adhesion of asphalt. Stiffness of asphalt binders is characterized as a function of loading time and temperature. The dynamic shear rheometer is used to characterize conditions at intermediate to upper pavement surface temperatures. The newly developed bending beam rheometer is used to characterize conditions at low temperatures, where thermal cracking is important. The direct tension test was developed to characterize fracture properties. A new phenomenon, low-temperature physical hardening, was identified. This phenomenon results in increased stiffness of the binder when held at a constant temperature at room temperature or below. This report describes a new aging procedure for simulating in-service oxidative hardening of asphalt binders. 475 pages. SHRP-A-369

Binder Characterization and Evaluation--Volume 4: Test MethodsDescribes the development of test methods for the characterization of asphalt cement. The information was used to develop models that relate the properties of asphalt cement to mixture properties and, in turn, to pavement performance. A method for the extraction and recovery of asphalt binder from asphalt mixes is also included. 193 pages. SHRP-A-370

Superpave Manual of Specifications, Test Methods and PracticesDocuments the Superpave mix design system for new construction and overlays. This system employs a series of new performance-based specifications, test methods and practices for material selection, accelerated performance testing, and mix design. Specifications and procedure formats are suitable for eventual standardization by the American Association of State Highway and Transportation Officials. SHRP-A-379

The Application of Small Nuclear Magnetic Resonance Spectrometers to Quality Control Measurements of Asphalt and Asphalt-Aggregate MixesIllustrates the classic wide-line nuclear magnetic resonance techniques used to measure the quantitative amounts of asphalt in asphalt-aggregate mixtures, including full 4-inch highway cores. A method for correlating related physical property measurements to nuclear magnetic resonance parameters is given for a wide range of neat asphalts. It is also shown how interactions between the asphalt and the aggregate in a mixture influence the physical properties of the asphalt and determine the physical properties of the mix. 42 pages. SHRP-A-382

Selection of Laboratory Aging Procedures for Asphalt-Aggregate MixturesPresents results of a preliminary investigation to evaluate short- and long-term aging methods for asphalt-aggregate mixtures. Test specimens were fabricated to represent extreme property levels. The four mixture combinations were prepared at two levels of permeability, representing good and moderate compaction conditions. The effects of aging were determined using the diametral resilient modulus test. 91 pages. SHRP-A-383

Aging: Binder ValidationOne short-term and four long-term aging methods were used to simulate aging of asphalt-aggregate mixtures in the field. Four aggregates and eight asphalts for a total of 32 different material combinations were tested using the different aging methods. Results of the aging studies were compared with the studies of asphalt binder and of asphalt mixed with fine aggregates. 81 pages. SHRP-A-384

Stiffness of Asphalt-Aggregate MixesPresents the evaluation of test systems for stiffness determination of asphalt-aggregate mixes, including 1) axial resilient stiffness, 2) diametral resilient stiffness, 3) resilient and dynamic flexural stiffness, and 4) dynamic shear stiffness. All tests were found to be sensitive to mix and test variables. Temperature had the greatest effect on axial, diametral, and flexural stiffness. 101 pages. SHRP-A-388

Laboratory Aging of Asphalt-Aggregate Mixtures: Field ValidationDescribes two test procedures that simulate short- and long-term field aging of asphalt-aggregate mixtures using oven aging technology. Analysis of field sites is used to develop prediction models for all combinations of climatic region and asphalt grade. 204 pages. SHRP-A-390

Field Validation of the Environmental Conditioning SystemEvaluates the environmental conditioning system and its ability to differentiate among asphalt concrete mixtures performance in regard to water sensitivity in the field. Twelve test sections were identified within four environmental regions. Specimens were also tested using two other asphalt wheel trackers. 194 pages.SHRP-A-396

Stage 1 Validation of the Relationship Between Asphalt Properties and Asphalt-Aggregate Mix Performance Various test methods and conditioning procedures were evaluated for their ability to produce specimens to predict asphalt-aggregate mix performance in terms of fatigue, permanent deformation, and thermal cracking. These specimens sought to represent post-construction pavement after short-term and long-term aging. Various combinations of asphalts and aggregates were subjected to a wheel-tracking device, thermal stress restrained specimen test, oven aging and water-sensitivity tests. 235 pages. SHRP-A-398

Low-Temperature Cracking: Binder ValidationTests were performed on both short-term and long-term aged specimens to (1) relate fundamental properties of asphalt cement and aggregate to the thermal cracking resistance of asphalt concrete mixtures, and (2) validate a hypothesis for low-temperature cracking developed for SHRP by Western Research Institute. Statistical analyses performed on the test results found that the results correlated well with those found previously. 106 pages. SHRP-A-399

Low-Temperature Cracking: Test SelectionDescribes the selection of the thermal stress restrained specimen test to evaluate low temperature cracking resistance of asphalt concrete mixtures. The test is conducted by cooling an asphalt concrete specimen at a specified rate while maintaining the specimen at a constant length. Four asphalts and two aggregates were tested. 106 pages. SHRP-A-400

Low-Temperature Cracking: Field Validation of the Thermal Stress Restrained Specimen TestEvaluates the validity of the thermal stress restrained specimen test as an accelerated performance test to predict low-temperature cracking of asphalt concrete mixtures. Included are construction histories, cracking observations, and temperature data collected from five test roads. 116 pages. SHRP-A-401

Water Sensitivity: Binder ValidationThe influence of binder properties on the moisture susceptibility of asphalt-aggregate mixes was evaluated by using thirty-two mixes with a combination of eight asphalts and four aggregates. Four procedures were used to test the mixes. 1) Environmental Conditioning System, 2) Oregon State University Wheel Tracker, 3) SWK Pavement Engineering/University of Nottingham Wheel Tracker, and 4) Net Adsorption Test. Because the testing procedures differed, it was not appropriate to make direct comparisons of the results. 104 pages. SHRP-A-402

Water Sensitivity of Asphalt-Aggregate Mixes: Test SelectionThis report describes the identification of the factors that influence water sensitivity of asphalt paving mixtures and the development of a test method to evaluate water sensitivity of asphalt concrete mixtures for mix design. The method was to be related to performance; no single current method was suitable. A test system was developed to evaluate the major factors that influence water sensitivity. 183 pages. SHRP-A-403

Fatigue Response of Asphalt-Aggregate MixesCovers the development of accelerated performance tests for defining the fatigue response of asphalt-aggregate mixes and their use in mix analysis and design systems. The report includes: a state-of-knowledge review for fatigue response of asphalt-aggregate mixes; a description of two pilot test programs developed to validate candidate tests, to provide an expanded database, and to develop models of fatigue behavior that might substitute for laboratory testing; and a description of a mix analysis and design system to be used to mitigate fatigue cracking. 309 pages. SHRP-A-404

The Superpave Mix Design Manual for New Construction and OverlaysRepresents the Superpave mix design system in a complete step-by-step format intended for engineers and technicians in public and private organizations to use when designing paving mixes for all classes of highways, from farm-to- market roads to urban freeways. 172 pages. SHRP-A-407

Level One Mix Design: Materials Selection, Compaction, and ConditioningConditioning A summary of the research of three aspects of the Superpave Level 1 mix design: volumetric mix design criteria for aggregates and mixes; compaction; and mix conditioning. A Delphi group process was used to select aggregate properties and specification values to be included in the Level 1 mix design procedure. Chapter 2 addresses the rationale for the selection of the gyratory compactor, its relation to field control, and validation. The final chapter summarizes the research associated with the development and validation of laboratory conditioning procedures for asphalt concrete mixes. It describes the procedures used to simulate both long- and short-term aging, as well as moisture sensitivity under repeated loading. 121 pages.SHRP-A-408

Validation of Relationships Between Specification Properties and PerformanceA summary of the two-stage validation of the proposed binder and mix specifications and tests. Stage 1 addresses the validation of the specifications and tests with laboratory data; Stage 2, with field performance data. The report is divided into four chapters. The first chapter outlines the validation process. Chapters 2 and 3 describe the Stage 1 and 2 validation, respectively, and include a comprehensive discussion of the laboratory testing undertaken to evaluate asphalt concrete performance in terms of permanent deformation, fatigue cracking, and low-temperature cracking. Chapter 4 addresses the validation testing conducted using modified materials. SHRP-A-409

Superior Performing Asphalt Pavements (Superpave): The Product of the SHRP Asphalt Research ProgramThis report describes the Superpave mix design system and the various parts that compose its operational characteristics. This report provides background for readers who want a more detailed description of the methodology, test methods, and theory behind Superpave than that provided in Superpave: Superior Performing Asphalt Pavements (SHRP-A-411). 156 pages. SHRP-A-410

Permanent Deformation Response of Asphalt-Aggregate MixesThis report describes SHRP's research conducted on permanent deformation of asphalt concrete mixes. The report is presented in three sections: one on the development of a series of accelerated performance tests to measure the permanent deformation response and a constitutive relationship to define it; validation of the binder properties included in the SHRP binder specification; and the use of the test methodology in an asphalt concrete mix design and analysis system. 438 pages.SHRP-A-415

Accelerated Performance-Related Tests for Asphalt-Aggregate Mixes and Their Use in Mix Design and Analysis SystemsA summary of the processes that led to the selection of the SHRP tests for fatigue, permanent deformation, thermal cracking, aging, and water sensitivity. Inherent in this test selection process was the emphasis on the ability of the tests to measure fundamental material properties that, when incorporated into prediction models, will depend less on empirical correlations than has traditionally been the case. Also included are the results of validation studies for each of the tests and frameworks for the use of the tests in mix design and analysis. Several levels of design are provided for each distress, some of which incorporate reliability concepts. SHRP-A-417

The SHRP Asphalt Research Program: 1990 Strategic Planning DocumentDescribes SHRP's asphalt research program, emphasizing goal definition and program structure. It illustrates available methods of data analysis, in particular the free-form, intuitive approach used for interpretation and synthesis to achieve specific products when rigorous mathematical methods are ineffective. Presents restructuring options for increased effectiveness in attaining goals with set time and budget constraints. 96 pages. SHRP-A/UWP-90-007

Absorption of Asphalt into Porous AggregatesExamines current knowledge concerning how aggregate properties influence absorption and how absorption can best be determined for practical use. Discusses methods for recovery of unabsorbed asphalt to ascertain the extent and importance of selective absorption, and methods to minimize the adverse effects of absorption on pavement performance. 33 pages.SHRP-A/UIR-90-009

A Literature Review of Liquid Antistripping Agents, Mineral Additives, and Tests for Measuring StrippingFocuses upon the chemistry of liquid amino base antistripping agents and mineral agents, and their contribution to adhesion and resistance of the asphalt- aggregate bond from the intrusion of water. Tests performed to evaluate these agents are also reviewed. (See also Summary Report on Water Sensitivity, SHRP-A-304.) 19 pages. SHRP-A/UIR-90-016

HP-GPC and Asphalt Characterization Literature ReviewDescribes the use of High Pressure Gel Permeation Chromatography to characterize asphalt properties and the relationship of these parameters to pavement performance. 140 pages. SHRP-A/UIR-91-503

The Effect of the Physical and Chemical Characteristics of the Aggregate on BondingReviews literature pertaining to physical and chemical characteristics of aggregates that have a significant effect on the bonding between aggregate and the asphalt. Research focused on the role played by morphology, electrical properties, and the mineral composition of the aggregate in its interaction with water. The report also examines the chemical functionalities in both asphalt and aggregates that play a predominant role in bonding, as well as the effect of surface modification of the aggregate and the use of antistripping agents. 23 pages. SHRP-A/UIR-91-507

Factors Influencing Mix Setting Characteristics and Tests to Predict Mix Setting CharacteristicsReviews the available literature pertaining to the various asphalt and aggregate properties that influence the setting characteristics of the mix. The report also identifies the various tests used to measure such mix characteristics. 13 pages. SHRP-A/UWP-91-508

The SHRP Materials Reference Library Aggregates: Chemical, Mineralogical, and Sorption AnalysesSummarizes the data for aggregates (two limestones, two granites, one basalt, one calcareous sandstone, one greywacke, and four gravels) collected as reference materials. These aggregates represent a geographically and lithologically diverse group of materials spanning the more commonly utilized bituminous aggregates. 88 pages. SHRP-A/UIR-91-509

Chemical Properties of Asphalts and Their Relationships to Pavement PerformanceDescribes the current status of the SHRP chemical studies of petroleum asphalt. The report attempts to correlate some of the known chemical properties of asphalt with pavement performance characteristics. 30 pages. SHRP-A/UWP-91-510

Prediction of Fatigue Cracking and Rutting in Asphalt Pavements by Small-Scale Centrifuge ModelsCentrifuge modeling was investigated to determine its feasibility for the prediction of fatigue cracking and rutting in full-depth asphalt pavements. A small-scale model of a pavement section was constructed and subjected to repeated loading tests in a centrifuge. Resilient tensile strains were measured at the bottom of the asphalt layer and the accumulated permanent deformations near the pavement surface. The models were tested to 10,000 repetitions, but more than one million repetitions may be required to induce fatigue cracking. A static load test also was performed after the repeated load test. 82 pages. SHRP-ID/UFR-91-516

Preliminary Analysis of BPR DataDescribes a preliminary analysis of asphalt cement samples collected by the Bureau of Public Roads (BPR) from 1954 to 1956. Samples from 210 construction projects in 26 states were collected. No trends or simple correlations were found between the pavement performance variables measured and the asphalt binder and mix properties selected for this analysis. 57 pages. SHRP-A/UIR-91-520

Experimental Design Guidelines for Asphalt Research Contractors, Revised 1991Examines the objectives of the asphalt research program and the role of experimental designs; the need for application of experimental designs; the selection of materials for the materials reference library; the asphalt program database; and the application of experimental design concepts to the development of an asphalt mix design system. 35 pages. SHRP-A/UWP-91-522

Evaluation of Laboratory Procedures for Compacting Asphalt-Aggregate MixturesExamines three compaction methods: Texas gyratory, kneading, and rolling wheel compaction. Unlike static and impact compactors, these compactors subject the densifying mixture to shearing motions similar to those induced during field compaction. Differences among the compaction methods are greatest for mixtures with low air voids, presumably because pore pressures are larger when there are fewer air voids in the mixture. Depending on their design and operation, compactors within a given genre may produce specimens having quite different engineering properties. 265 pages. SHRP-A/UWP-91-523

Validation in the SHRP Asphalt Research Program (October 1991)Development of performance-based specifications requires validation of those properties identified as important determinants of pavement performance. This report describes the first two stages of the three-stage validation process to be completed through SHRP's research program, and the third stage, to be performed by the long-term pavement performance program. 40 pages. SHRP-A/UWP-91-525

The Use of Conversion Residue as a Component in Asphalt CementDescribes why conversion residue, as a blending component in heavy fuel oils or as a refinery fuel, provides superior resistance to moisture-induced damage and similar hardening characteristics of conventional asphalt when blended into paving grade asphalt. 105 pages. SHRP-ID/UFR-92-610

Development of a Technique for In Situ Measurement of Water at the Asphalt/Model Siliceous Aggregate InterfaceDescribes the development of a method for measuring water in situ at the interface between an asphalt and a model siliceous aggregate. Based on Fourier transform infrared spectroscopy in the multiple internal reflection mode, the technique is useful for evaluating asphalt/siliceous model aggregate mixtures in terms of 1) water susceptibility of an asphalt/aggregate mixtures, 2) effectiveness of antistripping agents, 3) effects of aggregate surface contamination and environmental temperature on water stripping, and 4) water diffusion through asphalts on an aggregate. Test results for measuring the bond strength of an asphalt on an aggregate in the presence of water are given. 56 pages. SHRP-ID/UFR-92-611

A Differential Scanning Calorimetry Study of Asphalt BindersExamines the use of differential scanning calorimetry for studying the thermal properties and behaviors of asphalt. This technique provides parameters for comparing the glass transition temperatures; endothermic behavior of asphalt fractions and whole asphalts; aging; and slow cooling and heat rate effects of eight SHRP core asphalts and several other asphalts. 43 pages. SHRP-A/UFR-92-612

Review of State and Industry Reports on Asphalt Properties and Relationship to Pavement PerformanceReviews results of ten studies on the relationship between asphalt binder and mix properties, both physical and chemical, and the field performance of pavements. Four areas of pavement performance were measured: stripping, low temperature transverse cracking, rutting and bleeding. (See also Asphalt Properties and Relationships to Pavement Performance: Literature Review, SHRP-A-314.) 161 pages.SHRP-A-623

Bibliographies for Physical Properties of Asphalt CementContains 497 records complied from the Compendex Plus and the National Technical Information Service databases. Included are studies from technical journals, books, conference proceedings, and research reports relevant to the properties of asphaltic materials and their performance. The bibliography has five sections: durability; characterizations; thermal cracking; moisture damage; and fracture, fatigue, and rutting. 530 pages. SHRP-A-626

Advanced High Performance Gel Permeation Chromatography MethodologyExplores the use of high performance gel permeation chromatography as a means of studying asphalt composition and intermolecular interaction. SHRP core asphalts, their acid-base fractions, and laboratory-oxidized counterparts were analyzed. Based on the concept that molecular size distribution and the molecules' ability to assemble into larger entities in solution and into networks in neat asphalt are crucial to the performance of the asphalt. Attributes of the network formed will determine the asphalt's ability to resist thermal shock, for example, by providing strength and elasticity. 122 pages. SHRP-A-630

Review of Relationships between Modified Asphalt Properties and Pavement PerformanceThe scope of this literature review was to collect and summarize information in the technical literature relating modified asphalt properties to field pavement performance; to report the original findings and conclusions of the authors; and to note any trends or consensus. The resources reviewed included published literature, state highway agency research reports, inquiries to associations and manufacturers, and a search of the National Technical Information Services' database. One conclusion is that (a) asphalt modifiers do influence binder and mixture properties and hence performance; and (b) the ability to accurately interpret the association between asphalt modifiers and pavement performance has not been established through field studies. 228 pages.SHRP-A-631

SHRP Archival Database B User's Manual Version 2.0Contains instructions for the use of the SHRP Asphalt Research Program Archival Database. The report provides detailed, step-by-step instructions for retrieving, viewing, searching, and downloading of the files contained in the database. 72 pages. SHRP-A-632
Analysis of the Integrated Model of Climatic Effects on PavementsThe Federal Highway Administration showed that simulations of climatic effects on pavement temperature are capable of estimating pavement temperature when realistic input variables are used. An analysis also evaluated the influence of air temperature, solar radiation, percent sunshine, and thermal properties on calculated pavement temperatures. 158 pages. SHRP-A-637

Archival Database Specifications for the SHRP Asphalt Research ProgramContains information about the development of text and data files for the SHRP asphalt research program database. All files developed by the asphalt research program contractors followed the format set forth in this document. 37 pages. SHRP-A-638

Direct Tension Test ExperimentsDocuments the results from the Asphalt Institute, which led to the elimination of the direct tension test from the suite of SHRP performance tests for asphalt mixture specifications. 40 pages. SHRP-A-641

SHRP Materials Reference Library: Asphalt Cements: A Concise Data CompilationPresents a compilation of the chemical and physical properties of the asphalt cements contained in the SHRP Materials Reference Library. 27 pages. SHRP-A-645

The SHRP Materials Reference LibraryContains information on materials collected and stored at the SHRP Materials Reference Library and used by the asphalt research program contractors and other SHRP researchers. Describes the materials and how they were selected, their properties, procurement, storage, and processing. 231 pages.

Weather Database for the Superpave Mix Design SystemContains a database of 5,313 United States and 1,515 Canadian weather stations, which can be used to select a suitable performance grade of asphalt binder for a paving project, based on prevailing weather conditions in the area. This report briefly describes how the Superpave software functions and presents selected contents of the weather database in tabular form. 119 pages. SHRP-A-648A

Fluorometric Characterization of AsphaltsDiscusses the development of fluorescence microphotometry measurements of fluorescence intensity and spectra to characterize asphalts. Results demonstrate that fluorometric measurement of asphalt intensity has potential for monitoring asphalt oxidation occurring at the hot-mix and lay-down stages of asphalt production, as well as monitoring deterioration of in-service asphalt pavements. 85 pages. SHRP-A-649

Summary of Health Practices: The Use of Petroleum Asphalt in the Hot-Mix Paving IndustryReviews the literature regarding aspects of human health and the environment as related to the use of asphalt cements in the paving industry. The report cites exposure studies; clinical and epidemiological reports; animal toxicological studies; and discussions on polynuclear aromatic hydrocarbons in paving asphalts and asphalt emissions. 156 pages. SHRP-A-650

Development of an Asphalt Core TomographerA standard imaging procedure was used to develop a protocol to determine asphalt mass fractions in mixed or coarse aggregate cores. The protocol generates estimates of true mass fractions inside the core and can be used to study the three-dimensional internal deformations that occur as a core goes through different loading cycles. 101 pages. SHRP-A-656

Size Exclusion Chromatography and Ion Exchange Chromatography Separations of AsphaltDescribes experimental procedures used in the separation of asphalts by size exclusion chromatography and ion exchange chromatography. These experimental procedures were developed during the course of SHRP's binder characterization and evaluation program. A brief background section on chromatographic separations of asphalts is included. 29 pages. SHRP-A-663

Analysis of Sulfur Compound Types in AsphaltOutlines the evaluation of methods for determining sulfur compound types in asphalts from the SHRP Materials Reference Library. Methods used included infrared, tetrabutylammoniumperiodate oxidation, and oxidation with hydrogen peroxide. Whole asphalts and fractions were processed through liquid chromatographic separations. Sulfur types present at negligible concentrations were thiols, sulfones, and sulfonic acids. 46 pages. SHRP-A-667

The Characterization of Asphalt and Asphalt RecyclabilityDescribes the construction of a computer model to understand how asphalt components mix with one another. 26 pages. SHRP-A-675

Application of Acoustic Emission to Study the Cohesive and Adhesive Strength of AsphaltDescribes the development of a combined acoustic emission-poker chip test to measure the mechanical behavior of, and cavitation in, asphalt thin films. Combining results of the test with the appropriate stress analysis and fractography allows us to understand the controlling fracture mechanism of geometrically confined asphalt thin films. The test successfully differentiates different SHRP asphalts. The test provides a logical link among asphalt bulk rheological properties, microstructure in asphalt thin films, and performance properties of asphalt-aggregate mixtures. A laser contact angle goniometry technique and a modified blister test were developed to characterize, respectively, the asphalt surfaces and the adhesive strength between asphalt and aggregate surfaces. 273 pages. SHRP-A-682

Development of SHRP Asphalt Research Program Climatic DatabasesDescribes the development of two climatic databases for use in performance prediction models. The summary weather database includes a number of statistical parameters on seven-day maximum air temperatures and lowest annual temperatures for 6,000 weather stations in the United States and for 1,800 weather stations in Canada. 63 pages. SHRP-A-685

Guidelines for Asphalt Refiners and SuppliersDescribes various SHRP researchers' key findings, with emphasis on those fundamental chemical and physical properties of the binder that relate to its susceptibility to various distresses. Consideration and evaluation of the polar and non-polar molecules assists in understanding the performance of a given asphalt. The polars largely dictate the ability of an asphalt to resist permanent deformation. Low temperature cracking and fatigue cracking are largely influenced by the non-polar fraction. The impact of aging and asphalt compatibility on these distress modes is also discussed. 98 pages.SHRP-A-686

Development and Use of the Repeated Shear Test (Constant Height): An Optional Superpave Mix Design TestThis study investigated rut development in asphalt pavements to establish the foundations for the prediction of rutting in pavement structures. This paper presents advances in the characterization of asphalt-aggregate mixes by using finite element technology to predict permanent deformation. Although fatigue and thermal cracking may affect permanent deformation, such mechanisms are not discussed as they are considered of secondary importance. 94 pages.SHRP-A-698

Performance Prediction Models in the Superpave Mix Design SystemSHRP's asphalt research program developed performance-based asphalt binder and asphalt paving mix specifications to control three distress modes: permanent deformation; fatigue cracking; and low-temperature cracking. Detailed pavement performance models support the development of these specifications. They are an integral tool for mix design in the Superpave mix design system. This report summarizes the theoretical development, structure, and features of these performance models. The models can minimize a specific distress or combinations of different distresses, or they can set specification limits for specific materials and environments. 88 pages. SHRP-A-699

Superpave Video Asphalt Pavements that PerformBenefits of performance-based asphalt specifications. February 1992. 5 minutes. Tape No. 5

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