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The use of reclaimed asphalt pavement (RAP) in new asphalt mixes replaces a portion of the virgin aggregate and binder, which will help with cost saving in pavement construction as well provide several environmental benefits. Currently, the Federal Aviation Administration (FAA) has no requirements and specifications for the use of RAP in accordance to the FAA Specification P401 and this research will help with the development of such specifications. The objective of this study is to create Superpave mix designs for airfields using RAP and subject them to performance related testing to provide information regarding any issues with the mix design procedure. Another objective of this project is to perform and interpret the results of laboratory testing with regard to the behavior/performance of asphalt mixes containing RAP and evaluate their suitability for use in airport pavements The experimental plan in this study included 10 different hot mix asphalt (HMA) mixes made with three different binder grades (PG 64-22, PG58-28, PG76-22PM), three RAP sources (New York, California, Alabama), and two RAP percentages (25%, 40%). A control mix with no RAP was also tested for comparison. The results of this study will be used to develop mix designs for accelerated pavement testing at the FAA National Aviation Pavement Test Facility (NAPTF) in Atlantic City, New Jersey. The results indicate that meeting the FAA's voids in mineral aggregate (VMA) requirement was problematic and while developing the mix designs with RAP the total binder content had to be reduced in order to meet the current FAA air void and VMA requirements. Performance testing showed that incorporation of RAP will improve the performance properties when compared to their respective control mixes. The statistical analysis showed that percent of RAP (by binder replacement rate) is the most significant factor affecting all performance testing and that binder grade is the least significant factor on all performance testing. It is recommended that results from this study be validated with more performance testing, including additional testing with different binder grades and performance testing for low temperature cracking. There also needs to be more testing on mix designs for airfield pavement with the addition of RAP to develop voids filled with asphalt (VFA) and dust proportion (DP) specifications.
The objective of this research was to make an assessment of the relative performance of recycled versus new asphalt concrete pavement surfaces constructed for airport facilities. To make this assessment, pavement condition index (PCI) surveys and tests on core samples from the hot-mix recycled pavements located on the airports at Needles, California and Valley City, North Dakota were conducted. Both pavements have a condition rating of very good. The survey and test data were compared with those for recycled highway and virgin material Navy airfield pavements. The recycled pavement at Needles is performing as good as those Navy pavements constructed with virgin material. The recycled pavement at Valley City has a higher deterioration rate than the Navy pavements but this could be attributed to the harsh climate found in North Dakota. The results of this study show that hot-mix recycling was successful at these airports but additional studies are required to determine the applicability of Asphalt Concrete (AC) recycling for reconstruction at all airports. Keywords: Recycled concrete, asphalt, pavement surfaces, airport facilities, Navy airfield pavements, hot-mix recycling.
While the research and development of the SUPERPAVE asphalt mixture design and analysis system did address the use of polymer modified asphalt binders in the specification of material performance properties, no recommendations or procedural guidelines were given for the use of recycled materials. The use of recycled asphalt pavements (RAP) in new paving mixtures is not an innovative idea. RAP has been called one of the most recycled materials in the world, and its use in paving mixtures has been shown to have environmental, economic and performance benefits. In this study, four different RAP stockpiles were sampled and the characteristics of each RAP material were investigated in terms of binder content, aggregate gradation and the rheologic characteristics of the reclaimed RAP binder. The reclaimed RAP binders were blended with several different virgin performance graded binders in order to determine how RAP binder concentration affected the stiffness and performance grade of the RAP -- virgin binder blends. Recommendations were made on how to select virgin binder grade andor RAP concentration combinations to fulfill a project's binder grading requirements. The effects of RAP were also investigated in terms mixture design, and recommendations were made with regards to material handling and specimen fabrication procedures. Asphalt concrete mixtures containing RAP were characterized in terms of stiffness and resistance to plastic strain using SUPERPAVE testing methods, and the results of these tests were compared to those of virgin material mixtures. Assuming a simulated pavement cross section and traffic loading, the results of this performance testing were used in performance prediction models to estimate how pavements constructed with RAP would perform compared to those made from 100% virgin materials. The predicted performance of pavements containing up to 40% RAP (by weight) was found to be similar or slightly better than that of virgin material pavements.
This volume highlights the latest advances, innovations, and applications in bituminous materials and structures and asphalt pavement technology, as presented by leading international researchers and engineers at the RILEM International Symposium on Bituminous Materials (ISBM), held in Lyon, France on December 14-16, 2020. The symposium represents a joint effort of three RILEM Technical Committees from Cluster F: 264-RAP “Asphalt Pavement Recycling”, 272-PIM “Phase and Interphase Behaviour of Bituminous Materials”, and 278-CHA “Crack-Healing of Asphalt Pavement Materials”. It covers a diverse range of topics concerning bituminous materials (bitumen, mastics, mixtures) and road, railway and airport pavement structures, including: recycling, phase and interphase behaviour, cracking and healing, modification and innovative materials, durability and environmental aspects, testing and modelling, multi-scale properties, surface characteristics, structure performance, modelling and design, non-destructive testing, back-analysis, and Life Cycle Assessment. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster new multidisciplinary collaborations.
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.
Highway engineers are facing the challenge not only to design and construct sustainable and safe pavements properly and economically. This implies a thorough understanding of materials behaviour, their appropriate use in the continuously changing environment, and implementation of constantly improved technologies and methodologies. Bituminous Mixtures and Pavements VII contains more than 100 contributions that were presented at the 7th International Conference ‘Bituminous Mixtures and Pavements’ (7ICONFBMP, Thessaloniki, Greece 12-14 June 2019). The papers cover a wide range of topics: - Bituminous binders - Aggregates, unbound layers and subgrade - Bituminous mixtures (Hot, Warm and Cold) - Pavements (Design, Construction, Maintenance, Sustainability, Energy and environment consideration) - Pavement management - Pavement recycling - Geosynthetics - Pavement assessment, surface characteristics and safety - Posters Bituminous Mixtures and Pavements VII reflects recent advances in highway materials technology and pavement engineering, and will be of interest to academics and professionals interested or involved in these areas.
This research effort was focused on evaluating the feasibility of using minimally processed reclaimed asphalt pavement (RAP) as aggregate replacement in concrete pavements. This research demonstrated that concretes with up to 50 percent of the fine aggregates and 100 percent of the coarse aggregates replaced with RAP were suitable for concrete pavement. A statistical experimental design procedure (response surface methodology - RSM) was used to investigate proportioning RAP concrete mixtures to achieve desired performance criteria. Based on the results of the RSM investigation, two concrete mixtures were selected for further evaluation: a high RAP mix with fine and coarse aggregate replacement rates of 50 and 100 percent respectively, and a "high" strength mix with one half of the RAP used in the high RAP mix. Both mixes met MDT concrete pavement specifications for slump (1.5 inches), air content (6 percent), and 28-day compressive and tensile strengths (3,000 psi and 500 psi, respectively). These two concrete mixtures were subjected to a suite of mechanical and durability tests to evaluate their potential use in Montana roadways. Mechanical properties tested were compressive and tensile strength, elastic modulus, shrinkage, and creep. Durability tests included alkali-silica reactivity, absorption, abrasion, chloride permeability, freeze-thaw resistance, and scaling. Overall, both mixes performed adequately in these mechanical and durability tests, although it is important to note that the inclusion of RAP had an obvious negative impact on nearly every property tested relative to those of control mixes made with 100 percent conventional aggregates.
Keywords: RAP, asphalt concrete, pavements recycling.