Download or read book Simple and Practical Tests for Rutting Evaluation of Asphalt Mixtures in the Balanced Mix Design Process written by Ilker Boz and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Virginia Department of Transportation (VDOT) is currently using the asphalt pavement analyzer (APA) as a testing tool to screen the rutting potential of asphalt mixtures as part of its balanced mix design (BMD) method. However, the cost and availability of APA equipment in VDOT and contractor laboratories and the speed of testing are main barriers to the routine use of APA in the BMD process, especially during the production of asphalt mixtures. The existence of alternative tests that are simple, practical, and performance indicative can help facilitate the implementation of BMD into practice. The monotonic loading tests (hereinafter “monotonic tests”) have been proposed to address the need for simpler tests. This study was undertaken to assess the feasibility of using monotonic tests as a screening tool to evaluate the rutting potential of dense-graded asphalt surface mixtures as part of the BMD initiative in Virginia. In this effort, three monotonic tests, the indirect tensile at high temperature (IDT-HT) test, rapid rutting (RR) test, and Marshall stability and flow (MS) test, identified from the literature, were evaluated using 17 plant-produced asphalt mixtures with “A” and “D” designations. The results were used to assess the monotonic tests and the APA test relative to each other through several performance metrics and correlations with fundamental rutting tests and mechanistic-empirical–based simulations. The results were also used to develop performance threshold criteria for the considered tests. The results showed that the IDT-HT and RR tests can be used to screen the rutting potential of asphalt mixtures meeting VDOT mixture volumetric and gradation requirements for the A and D mixtures. The initial performance criteria for the IDT-HT and RR tests were established for these mixtures. Based on the results, the IDT-HT test was found to be the most suitable alternative test to the APA test. The study recommends using the IDT-HT test as part of the BMD initiative with a corresponding minimum strength of 133 kPa as a performance criterion based on the testing conditions used in this study. Implementation of traffic-based performance criteria for the A and D mixtures should be explored, as the current practice does not differentiate the performance between these mixtures. The results of the IDT-HT, RR, and the APA tests should be compared and correlated with those from fundamental rutting tests and with performance predictions obtained from mechanistic-empirical pavement design simulations using a larger number of mixtures to verify the findings of this study. In addition, the results should be compared to field performance results for full assurance that the implemented tests and associated threshold values are appropriate. Fine-tuning the testing process for the IDT-HT, RR, and APA tests and establishing precision estimates and statements are necessary for proper quality assurance practices. The study further recommends hands-on training and demonstration of the tests being considered by VDOT as part of the BMD implementation.

Download or read book Balanced Mix Design for Surface Asphalt Mixtures Phase I Initial Roadmap Development and Specification Verification written by Stacey D. Diefenderfer and published by . This book was released on 2021 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Virginia Department of Transportation (VDOT), as with many owner agencies, is interested in ways to facilitate the increased durability of asphalt mixtures in an effort to make its roadway network more sustainable, longer lasting, and more economical. The balanced mix design (BMD) method addresses this through the incorporation of performance criteria into mix design and acceptance. VDOT has committed to the implementation of the BMD method in an effort to improve asphalt mixture performance. The purpose of this study was to continue advancing efforts toward VDOT’s implementation of BMD by developing a performance-based mix design roadmap for application in Virginia. The proposed roadmap was developed to provide guidance on the specific needs and activities necessary for VDOT to adopt the BMD concept. A specific need outlined in the roadmap was to validate and/or refine the selected initial performance tests and associated test threshold criteria. To accomplish this, 13 asphalt mixtures were evaluated using performance-measuring laboratory tests. The results of these tests were used to assess the initial performance tests and test threshold criteria selected for BMD use. The proposed roadmap is intended to be an evolving resource for outlining the agenda of activities necessary for implementation of BMD. The roadmap identified specific needs addressed in this study. Based on the results for the mixtures evaluated as part of those needs, the Asphalt Pavement Analyzer (APA) rut test (hereinafter “APA test”); indirect tensile cracking test (IDT-CT) (hereinafter “IDT-CT test”); and Cantabro mass loss test (hereinafter “Cantabro test”) are suitable for continued use in BMD. The current threshold criteria for all three tests were reasonable, based on additional testing and analysis. The study recommends that the roadmap for BMD continue to be refined to provide a clear direction of the activities necessary for implementation and serve as a resource to evaluate progress. VDOT should continue to use the APA, IDT-CT, and Cantabro tests for BMD. The APA and IDT-CT test results should be compared and correlated with those of fundamental rutting and cracking tests, respectively, and with performance predictions obtained from mechanistic-empirical pavement design simulations and field performance for full assurance that test threshold values are appropriate. In addition, the differences in test results attributable to mixture reheating and different specimen types, such as laboratory-compacted specimens and field cores, should be addressed. The study further recommends evaluating the Cantabro, IDT-CT, and APA test results to determine acceptable variability and establish precision statements.

Download or read book Innovative Assessment Tests and Indicators for Performance based Asphalt Mix Design written by Hamza Alkuime and published by . This book was released on 2019 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt: Asphalt mixes are designed to provide adequate resistance to various distresses including cracking, rutting, and moisture damage. Recently, more efforts are directed towards including performance assessment tests during the design and production of asphalt mixes. Performance-Engineered Mix Design (PEMD) or Balanced Mix Design (BMD) is a new and innovative design approach that incorporates performance assessment tests to optimize the design of asphalt mixes to provide adequate performance. Although transportation agencies are motivated to implement the PEMD approach, several research knowledge gaps and concerns need to be addressed before PEMD successful implementation. This research study aims to advance, develop, and implement performance-engineered design approach and specifications to extend the service life of asphalt pavements.The first phase of this research developed and evaluated a new and innovative monotonic cracking performance indicator called Weibull Cracking Resistance Index (WeibullCRI). The proposed indicator describes the entire load-displacement curve, which overcomes the limitations of the existing performance indicators. First, WeibullCRI was examined using an extensive laboratory evaluation of 16 different asphalt mixes. The results indicated that WeibullCRI was sensitive to variation in binder content and binder PG and the results were in good agreement with the expected cracking resistance based on the composition of the studied mixes. In addition, WeibullCRI had low variability in test results and higher number of various statistical groups. Next, the applicability of WeibullCRI as a unified approach to analyze the results of various monotonic assessment tests was investigated using data generated by other researchers and reported in the literature. The results indicated that WeibullCRI is able to interpret the testing results of various monotonic performance assessment tests (i.e., IDT- intermediate temperature, Semi-Circle Bending [SCB]- intermediate temperature, SCB-low temperature, Disk-Shaped Compact Tension [DCT], and Simple Punching Shear Test [SPST]) and various displacement measurement methods (i.e., actuator vertical displacement and Crack Mouth Opening Displacement [CMOD]). WeibullCRI was also sensitive to variation in test conditions (i.e., specimen notch depth, thickness, and air void content) and mix composition proportions (i.e., binder content, binder grade, aggregate type, NMAS, aging, rejuvenator dosages, and Recycled Asphalt Pavement [RAP] materials).The second phase of this study reviewed and evaluated the current monotonic cracking performance assessment tests and indicators including the developed WeibullCRI used to assess asphalt mix resistance to cracking. In this phase, the testing requirements of various test standards, key publications, concepts, calculation methods, physical meaning, and advantages and disadvantages of various performance indicators were reviewed. Then, the study investigated the validity of the most promising testing standards and indicators. Three testing standards and 12 performance indicators were considered. Several aspects were examined including 1) investigate the fundamental meaning of the variation in the load-displacement curve in terms of the change in mix resistance to cracking, 2) sensitivity of performance indicators to mix compositions, 3) variability in test results, 4) number of various statistical groups, 5) correlation between various performance indicators, 6) direct correlation between laboratory results of monotonic performance tests and indicators with the observed field cracking, and 7) ability to develop PEMD specifications. A comprehensive laboratory investigation was conducted using 33 different asphalt mixes included six Laboratory Mixed-Laboratory Compacted (LMLC) and 10 Plant Mixed-Laboratory Compacted (PMLC) asphalt mixes, and 17 field projects with known cracking performance. The results showed that WeibullCRI calculated from the IDT test to have the lowest test variability, maximum number of Tukey's honestly significant difference (HSD) groups, and have excellent correlation with cyclic cracking resistance assessment indicators as compared to the other monotonic performance indicators. In addition, the results demonstrated that there was no direct correlation between all monotonic performance indicators and the observed field cracking performance, therefore an alternative approach was proposed, evaluated, and validated to develop performance thresholds for the selected performance indicators. Three pass/fail cracking performance thresholds were proposed for WeibullCRI to distinguish between asphalt mixes with good, fair, and poor cracking resistance using the proposed approach.The third phase of this study focused on the development and evaluation of a new cyclic cracking assessment test called Multi-Stage Semi-circle bending Dynamic (MSSD). The test offers advantages over the available monotonic and dynamic cracking assessment tests and addresses major concerns to implement the PEMD (i.e., performance test validity, complex specimen preparation, and testing time). The developed MSSD test simulates the repeated loading (cyclic) in a reasonable testing time (less than 9 hours per test regardless of mix type), has a fixed loading sequence that works for mixes with different characteristics (e.g., mix composition, percent air void content, thickness, etc.), and utilizes testing equipment and specimen geometry similar to that used in monotonic tests. The laboratory evaluation results showed that the proposed test and its derived performance indicators were sensitive to mix composition and had lower variability compared to other dynamic tests. In addition, the MSSD performance indicators correlated well with the observed cracking performance in the field and were able to distinguish between projects with good and poor resistance to cracking. Based on the evaluation results, three pass/fail cracking performance thresholds were proposed to distinguish between asphalt mixes with good, fair, and poor resistance to cracking.The fourth phase of this research examined the most promising tests and performance indicators to evaluate the resistance of asphalt mixtures to rutting. Two tests (i.e., Hamburg Wheel Tracking test [HWTT], and Asphalt Pavement Analyzer [APA] rut test) and three rutting performance indicators (i.e., HWTT rut depth after 15,000 passes [HWTT15000], HWTT rut depth at 20,000 passes [HWTT20000], and APA rut depth after 8,000 cycles [APA8000]) were considered. An intensive laboratory investigation was conducted that included six LMLC, 10 PMLC, and field cores extracted from 17 field projects. The research findings showed that both HWTT and APA rut test provided similar rutting assessment for the evaluated mixes. The study recommended using the HWTT over the APA rut test since HWTT can be also used to assess the resistance of asphalt mixtures to moisture damage to moisture damage. Also, the study recommended using HWTT15000 over HWTT20000 as a performance indicator since it requires less testing time.The final phase of this research provided recommendations of the best testing standards, performance indicators, and performance specifications to assess asphalt mix resistance to cracking and rutting. In addition, it provided guidelines to demonstrate the use of the proposed tools during the design and/or production of asphalt mixes. It also proposed standards testing procedures for the newly developed WeibullCRI performance indicator and MSSD test.

Download or read book Evaluation of Laboratory Testing Systems for Asphalt Mixture Design and Evaluation written by and published by . This book was released on 2004 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Specification Criteria for Simple Performance Tests for Rutting written by Matthew W. Witczak and published by Transportation Research Board. This book was released on 2007 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance Tests for Hot Mix Asphalt HMA Including Fundamental and Empirical Procedures written by Louay Nadhim Mohammad and published by ASTM International. This book was released on 2006 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simple Performance Tester for Superpave Mix Design written by Ramon Francis Bonaquist and published by Transportation Research Board. This book was released on 2003 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: The global response to COVID-19 has demonstrated the importance of vigilance and preparedness for infectious diseases, particularly influenza. There is a need for more effective influenza vaccines and modern manufacturing technologies that are adaptable and scalable to meet demand during a pandemic. The rapid development of COVID-19 vaccines has demonstrated what is possible with extensive data sharing, researchers who have the necessary resources and novel technologies to conduct and apply their research, rolling review by regulators, and public-private partnerships. As demonstrated throughout the response to COVID-19, the process of research and development of novel vaccines can be significantly optimized when stakeholders are provided with the resources and technologies needed to support their response. Vaccine Research and Development to Advance Pandemic and Seasonal Influenza Preparedness and Response focuses on how to leverage the knowledge gained from the COVID-19 pandemic to optimize vaccine research and development (R&D) to support the prevention and control of seasonal and pandemic influenza. The committee's findings address four dimensions of vaccine R&D: (1) basic and translational science, (2) clinical science, (3) manufacturing science, and (4) regulatory science.

Download or read book Aggregate Tests for Hot mix Asphalt Mixtures Used in Pavements written by Thomas D. White and published by Transportation Research Board. This book was released on 2006 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction and research approach -- Findings -- Interpretation, appraisal, and application -- Conclusions and suggested research -- References -- Abbreviations used without definitions in TRB publications.

Download or read book Superpave Mix Design written by Asphalt Institute and published by . This book was released on 2001-01-01 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of a Simplified Test Method to Predict Rutting Characteristics of Asphalt Mixes written by James S. Lai and published by . This book was released on 1987 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Balanced Mix Design for Surface Mixtures 2020 Field Trials written by Stacey D. Diefenderfer and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Virginia Department of Transportation (VDOT) has been working toward the implementation of balanced mix design (BMD) for several years. During that time, special provisions have been developed to address dense-graded surface mixtures with reclaimed asphalt pavement (RAP) contents up to 30% and with RAP contents of 40% and above. In 2020, five field trials encompassing 12 mixtures were constructed to evaluate BMD mixtures designed and produced in accordance with VDOT’s special provision for surface mixtures with high RAP contents. Typical dense-graded Superpave surface mixtures were used as controls. This study documented and assessed these trials to provide information to evaluate the impact of various RAP contents and additives, production variability, reheating, and binder properties on BMD performance test results. Twelve mixtures were evaluated during the five field trials. The mixtures included combinations of different RAP contents, two binder grades, four recycling agents, and fiber. Volumetric and gradation analysis was performed on the mixtures. The Cantabro mass loss test (Cantabro test), the indirect tensile cracking test (IDT-CT), and the Asphalt Pavement Analyzer (APA) test were performed on laboratory-produced design specimens and non-reheated and reheated plant-produced, laboratory-compacted specimens. All findings and conclusions are limited to the mixtures evaluated. Based on the test results, mixtures containing 35% or greater RAP contents, softer binders, recycling agents, and fiber may be designed and produced to meet current BMD performance thresholds and current volumetric properties, gradation, and asphalt content requirements. It was found that some mixtures that were volumetrically designed under current VDOT specifications met BMD requirements. In addition, the expected trends in mixture performance testing were not always observed, likely due to masking by variability due to specimen fabrication practices or by inherent test variability. Results showed that modest relationships between non-reheated and reheated specimen results for the Cantabro test and IDT-CT were present. In addition, changes due to the use of a softer binder and/or recycling agents were seen in the BMD mixture binders as compared with the control mixture binder. Finally, comparisons of extracted and recovered binders from control and BMD mixtures were found to depend on the binder test under consideration, with different tests indicating differences in expected performance. Based on the outcomes of the study, a testing protocol capable of evaluating the performance of recycling agents used in BMD mixtures is needed. This protocol would provide a means for VDOT to evaluate and accept these materials such that their use in innovative mixtures can be allowed in a manner that preserves the goals of sustainable, longer-lasting, and cost-effective pavements. In addition, efforts should be made to determine the effect of asphalt binder properties on the overall performance of asphalt mixtures with a primary focus on cracking and durability to allow VDOT to specify better-performing binders for use in asphalt mixtures. This would allow for the further optimization of mixture properties that should result in improved mixture performance.

Download or read book Evaluation of Indirect Tensile Test IDT Procedures for Low temperature Performance of Hot Mix Asphalt written by Donald W. Christensen and published by Transportation Research Board. This book was released on 2004 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction and Research Approach -- Findings -- Interpretation, Appraisal, and Applications -- Conclusions and Recommendations -- References -- Appendixes.

Download or read book Simple Performance Test for Superpave Mix Design written by Matthew W. Witzcak and published by Transportation Research Board. This book was released on 2002 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Generation Mix Designs written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Recent changes to the Texas HMA mix-design procedures such as adaption of the higher PG asphalt-binder grades and the Hamburg test have ensured that the mixes routinely used on the Texas highways are not prone to rutting. However, performance concerns have been raised about these mixes, which are now “drier”, more difficult to compact, and more susceptible to cracking. This is particularly problematic with the dense-graded Type C and D mixes that are widely used throughout the State of Texas. Consequently, several new ideas are under consideration to either modify the existing mix-design criteria (target densities, VMA requirements, etc.) and/or to include new and simpler cracking test procedures. Of primary focus in this research project is the comparative evaluation of the following three mix-design procedures and making recommendations thereof: (1) the modified volumetric mix-design procedure; (2) the Hamburg (rutting) and Overlay (cracking) test based balanced mix-design procedure; and (3) a simplified balanced mix-design procedure with a simpler alternative cracking test. The research methodology and scope of work incorporates extensive literature review of the existing mix-design procedures, laboratory testing, and field validation including accelerated pavement testing (APT) and performance monitoring. This interim report provides a preliminary overview of the mix-designs and laboratory test evaluations of three commonly used Texas mixes (namely Type B, Type C, and Type D) based on the Texas gyratory, volumetric, and balanced mix-design procedures. As well as conducting round-robin tests in six different Texas laboratories to quantify the Overlay test variability and repeatability, the laboratory tests also included comparative evaluation of various cracking tests such as the indirect tension, direct uniaxial tension, and semi-circular bending. HMA mix workability and compactability tests for quantifying the constructability aspects of the mixes were also conducted and are discussed in this report. Construction details of the APT test sections are also discussed in this interim report."--abstract.

Download or read book Laboratory Evaluation of Rutting Potential of Asphalt Mixtures written by TF. Fwa and published by . This book was released on 1992 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes a laboratory procedure to evaluate the rutting potential of asphalt mixtures using a wheel tracking machine. Moving loads were applied through solid rubber tired wheels that travel with a reciprocating motion on slab specimens of asphalt mixtures. The specimens were prepared in parallepipedal steel molds by means of static compression to achieve fairly uniform density distribution within individual specimens. The machine allows rut tests to be conducted at different temperatures, magnitudes of applied loads, and speeds of loading. Results of a test program are reported to illustrate the application of the procedure to study the effects of temperature and loading speed on rut development in an asphalt mixture.

Download or read book Comparative Evaluation of Moisture Susceptibility Test Methods for Routine Usage in Asphalt Mixture Design written by Christopher J. DeCarlo and published by . This book was released on 2020 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Asphalt materials experience substantial amounts of environmental damage throughout their lives as surface layers in pavements. One of the most prominent forms of environmental damage, moisture-induced damage, is caused by the weakening of internal bonds of the material because of the presence of moisture in the voids of asphalt mixtures and is a common problem for asphalt pavements in wet climates. Moisture-induced damage is typically accounted for during asphalt mixture design by conducting performance tests to ensure the material is not susceptible to severe damage from moisture, although many of these methods have seen mixed amounts of success historically. The main objective of this study is to evaluate the ability of multiple asphalt mixture moisture susceptibility tests to identify good and poor performing mixtures with respect to moisture-induced damage to replace current mix design testing requirements. Ten plant-produced hot mix asphalt materials with established good and poor field moisture performance were subjected to various moisture susceptibility test methods. The results from these procedures are assessed to determine which procedure is most effective and practical as a moisture susceptibility test for routine usage during asphalt mixture design for transportation agencies. Results from this study suggest that performance tests with stiffness-based measurements, such as dynamic modulus paired with moisture conditioning and the saturated aging tensile stiffness procedure, show better correlation to field performance than traditional test methods such as AASHTO T-283, Standard Method of Test for Resistance of Compacted Asphalt Mixtures to Moisture-Induced Damage, and that the Hamburg wheel tracker test is the most effective and practical test method to reliably identify mixtures prone to experiencing moisture-induced damage.

Download or read book Refining the Simple Performance Tester for Use in Routine Practice written by Ramon Francis Bonaquist and published by Transportation Research Board National Research. This book was released on 2008 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB¿s National Cooperative Highway Research Program (NCHRP) Report 614: Refining the Simple Performance Tester for Use in Routine Practice explores the develop of a practical, economical simple performance tester (SPT) for use in routine hot-mix asphalt (HMA) mix design and in the characterization of HMA materials for pavement structural design with the Mechanistic-Empirical Pavement Design Guide.