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The test results showed that unacceptable performance was predicted when the mixtures tested were subjected typical construction variability. A procedure was presented. The intent was to provide state agencies, asphalt mixture designers, and contractors the necessary tools and guidance to produce an asphalt mixture in which the expected performance can be evaluated before it was placed in the roadway. The overall benefit for such a system would lead to the design and construction of asphalt pavement that would last longer.
The final product of the Strategic Highway Research Program (SHRP) Asphalt Research Program is the SUPERPAVE (registered trademark) 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. This report documents these new specifications and procedures in a format suitable for eventual American Association of State Highway and Transportation Officials (AASHTO) standardization.
Existing test methods to determine moisture sensitivity in Hot Mix Asphalt (HMA) are time consuming and inconsistent. This research focused on wheel tracking devices to develop a rapid test method to evaluate moisture sensitivity. The Asphalt Pavement Analyzer (APA) and the Hamburg Wheel Tracking Device (HWTD) were used for this research. Compacted cylindrical samples were fabricated using a Superpave gyratory compactor. This study selected two most commonly used mixtures, SM-12.5A with Pg 64-22 binder in overlay projects and SM-19A mixtures with PG 64-22 binder for major modification projects at the Kansas Department of Transportation. Test results show that APA tests could induce stripping in most samples without any anti-stripping agent, which could be indentified visually. However, APA results do not indicate any stripping inflection point while the HWTD results show stripping inflection points, which are important to indentify stripping potential of mixtures. The APA results show that wet tests are severe at lower temperatures whereas dry tests show high rut depths at higher temperatures. The HWTD results show improvement in the performance using anti-stripping agents at later stage. The HWTD test is more effective than the APA as a rapid test method for determining moisture sensitivity of HMA. Laboratory results from this study should be verified and correlated with field performance.
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.
Containing 13 papers from the December 2000 conference in Orlando, Florida, this book covers the use of the PURWheel laboratory tracking device, the Asphalt Pavement Analyzer, the identification of aggregate role, the evaluation of sensitivity, fine aggregate angularity, guidelines for the selection
TRB's National Cooperative Highway Research Program (NCHRP) Report 704: A Performance-Related Specification for Hot-Mixed Asphalt provides a proposed performance-related specification (PRS) for hot-mix asphalt (HMA) in the form of the Microsoft Windows-based Quality-Related Specification Software (QRSS). The QRSS is a stand-alone program for Microsoft Windows (versions XP and 7) that employs a database of pre-solved solutions of the Mechanistic-Empirical Pavement Design Guide. The program is capable of (1) calculating the predicted rutting, fatigue cracking, and low-temperature (thermal) cracking of an HMA pavement from the mix volumetric and binder and aggregate properties of the as-designed HMA (typically the job mix formula) and (2) comparing them with predictions calculated from the contractor's lot or sub-lot quality assurance data for the same properties.
TRB's National Cooperative Highway Research Program (NCHRP) Report 567: Volumetric Requirements for Superpave Mix Design examines whether changes to the recommended Superpave mix design criteria for voids in mineral aggregate, voids filled with asphalt, and air voids content might further enhance the performance and durability of hot-mix asphalt.