Engineered Frameworks For Evaluating The Use Of Recycling Agents In Surface Asphalt Mixtures For Virginia
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Engineered Frameworks For Evaluating The Use Of Recycling Agents In Surface Asphalt Mixtures For Virginia
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Author : Jhony Habbouche
language : en
Publisher:
Release Date : 2023
Engineered Frameworks For Evaluating The Use Of Recycling Agents In Surface Asphalt Mixtures For Virginia written by Jhony Habbouche and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with Pavements, Asphalt concrete--Recycling categories.
In recent years, several state highway agencies have introduced special provisions and specifications to allow the use of higher contents of reclaimed asphalt pavement (RAP) in asphalt surface mixtures. The challenges associated with high RAP mixtures can be addressed through the use of additives such as recycling agents (RAs) and/or softer binders. Currently, there are no specific guidelines or specifications available to evaluate the acceptability of RAs in Virginia. The purpose of this study was to evaluate the short- and long-term effectiveness of RAs in improving the performance of asphalt mixtures, particularly those with high RAP contents. Another objective of the study was to establish a performance-based framework to determine the acceptability of a specific RA product for inclusion in the Virginia Department of Transportation’s Approved Product List. Both objectives were achieved by benchmarking recycled binder blends (Phase I) and mixtures (Phase II). These were then compared in terms of laboratory performance to commonly used virgin asphalt binders and mixtures in Virginia. Moreover, a comprehensive review of the literature and information from state departments of transportation and RA suppliers on the current state of the practice regarding the use of recycled materials and RAs in asphalt mixtures was summarized. Component materials, including three virgin asphalt binders, RAP and aggregate materials from three different sources, and six RAs, were collected and tested. Phase I involved testing virgin and RAP binders; combinations of virgin binder and RAP binder; and combination of virgin binder, RAP binder, and RAs. A total of 26 binder blends were evaluated at various aging conditions through numerous rheology- and chemistry-based tests. In Phase II, 10 asphalt mixtures were designed and evaluated for durability, resistance to rutting, and resistance to cracking at various aging conditions. Cross-scale evaluation of asphalt binder and mixture testing data was established. Finally, preliminary verification was performed using data collected from various field trials constructed in Virginia. Based on the binders and mixtures tested in this study, the effectiveness of RAs in improving the properties of asphalt binder blends is specific to the product being used and to the targeted temperatures or conditions. Moreover, RAs can enhance the performance and increase the use of recycled materials in asphalt mixtures provided that the correct and suitable dosage of RA product is determined through a performance-based testing framework. The study recommends the following: (1) adopting the streamlined frameworks presented in this study to determine the acceptability of a given RA; (2) further validating the presented framework using different component materials; (3) employing balanced mix design tests to assess the performance characteristics of surface mixtures (with A and D designations) with RAs and drafting a roadmap; (4) collecting and further evaluating the field performance of all trials involving high RAP, RAs, and/or softer binders; (5) investigating the availability and activity of binders, especially with RAs, in RAP materials; (6) evaluating and establishing a protocol to assess the consistency of RAP materials; and (7) quantifying the environmental and economic impacts of using surface mixtures with high RAP contents and/or RAs.
Evaluating The Effects Of Recycling Agents On Asphalt Mixtures With High Ras And Rap Binder Ratios
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Author : Amy Epps Martin
language : en
Publisher:
Release Date : 2020
Evaluating The Effects Of Recycling Agents On Asphalt Mixtures With High Ras And Rap Binder Ratios written by Amy Epps Martin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Asphalt categories.
"More than 90 percent of highways and roads in the United States are built using hot-mix asphalt (HMA) or warm-mix asphalt (WMA) mixtures, and these mixtures now recycle more than 99 percent of some 76.2 million tons of reclaimed asphalt pavement (RAP) and about 1 million tons of recycled asphalt shingles (RAS) each year. Cost savings in 2017 totaled approximately $2.2 billion with these recycled materials replacing virgin materials. The TRB National Cooperative Highway Research Program's NCHRP Research Report 927: Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios presents an evaluation of how commercially available recycling agents affect the performance of asphalt mixtures incorporating RAP and RAS at high recycled binder ratios."--
Evaluation Of Hybrid Rubber Modified Asphalt Mixtures And Pavements A Case Study In Virginia
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Author : Jhony Habbouche
language : en
Publisher:
Release Date : 2023
Evaluation Of Hybrid Rubber Modified Asphalt Mixtures And Pavements A Case Study In Virginia written by Jhony Habbouche and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with Asphalt--Additives categories.
Several state departments of transportation have recognized the benefits of modified asphalt mixtures in resisting multiple modes of climate- and load-induced distresses in flexible pavements. Throughout the past 50 years, asphalt binders have been modified with various components such as styrene-butadiene-styrene (SBS) polymers, ground tire rubber, chemicals (e.g., acid), recycled engine oils, etc., to achieve the desired properties. Hybrid rubber modified asphalt (HRMA) is an innovative engineered additive derived from ground tire rubber, elastomeric SBS polymers, and additive technologies. HRMA is specifically formulated to improve the high temperature stiffness and elastic properties of performance graded binders and the storage stability of modified binders. The purpose of this study was to document and assess HRMA field trials constructed in Virginia. This study documented and evaluated the constructability and laboratory performance of two plant-produced HRMA mixtures compared with the Virginia Department of Transportation (VDOT) typical SBS-modified surface mixtures as reference mixtures. No changes from routine established practices in terms of surface preparation, production at the plant, or paving operations were reported. The four mixtures were evaluated in terms of durability, dynamic modulus, resistance to rutting, and resistance to cracking using multi-level performance tests (basic, intermediate, advanced). All the derived observations indicated that HRMA modification could be as beneficial as regular SBS modification and could provide similar or better performance properties and characteristics for the resultant mixtures. The study recommends that VDOT consider the use of HRMA surface mixtures as an alternative to the current use of regular SBS-modified surface mixtures on higher-volume facilities. Since the sections evaluated in this study were placed in 2021, the 2-year performance data and corresponding observations are still considered preliminary. Continued monitoring of field performance will be needed to quantify any benefit of HRMA mixtures in comparison with regular SBS-modified surface mixtures. The study also recommends additional field trials with HRMA mixtures for further performance evaluation.
Engineering Properties Of Recycled Asphalt Mixtures
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Author : Thomas William Kennedy
language : en
Publisher:
Release Date : 1983
Engineering Properties Of Recycled Asphalt Mixtures written by Thomas William Kennedy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1983 with Asphalt categories.
Evaluation Of Using Higher Percentages Of Recycled Asphalt Pavement In Asphalt Mixes In Virginia
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Author : G. W. Maupin
language : en
Publisher:
Release Date : 2008
Evaluation Of Using Higher Percentages Of Recycled Asphalt Pavement In Asphalt Mixes In Virginia written by G. W. Maupin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Pavements, Asphalt categories.
In 2007, the Virginia Department of Transportation (VDOT) decided to allow higher percentages of recycled asphalt pavement (RAP), i.e., more than 20 percent, in hot-mix asphalt with no change in binder grade. Because of this increase, one section of the contract provisions in certain plant-mix overlay schedules around the state had to be rewritten to raise the limit on the proportion of recycled material to 30 percent from the customary 20 percent. The allowance of higher RAP percentages should result in a lower cost of asphalt mix per ton, especially given the recent rising cost of asphalt cement and virgin aggregates.The purpose of this study was to estimate the effect of increased RAP percentages on performance and relative mixture cost on specific VDOT paving projects in 2007. Projects using more than 20 percent RAP were conducted in three VDOT districts. In addition, several value engineering proposals for using increased percentages of RAP submitted by contractors were accepted and carried out in another district. Six contractors produced a total of 129,277 tons of mix containing 21 to 30 percent RAP from seven asphalt plants in four VDOT districts. Mix containing less than 20 percent RAP was also sampled and tested for comparison purposes. Laboratory tests performed on samples collected during production revealed no significant difference between the higher RAP mixes and the control mixes for fatigue, rutting, and susceptibility to moisture. Binder was recovered from asphalt mix sampled during construction and graded to determine the effect of adding higher percentages of RAP. There were no construction problems attributed to the use of the mix with the higher RAP percentage. Only slight price adjustments were applied to 2 of the 10 high-RAP projects, and these adjustments were not due to the higher RAP percentage. Analysis of bid data found that the inclusion of a contract specification that allowed the higher RAP percentages had a small, statistically insignificant impact on the bid prices for surface mix items. However, value engineering proposals received for jobs that were not advertised with the high-RAP specification showed that the use of over 20 percent RAP could reduce costs in at least some cases.
Balanced Mix Design For Surface Asphalt Mixtures
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Author : Stacey D. Diefenderfer
language : en
Publisher:
Release Date : 2021
Balanced Mix Design For Surface Asphalt Mixtures written by Stacey D. Diefenderfer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with Pavements, Asphalt--Design and construction categories.
In 2017, the Virginia Department of Transportation (VDOT) began to evaluate the feasibility of introducing performance requirements into mix design using the balanced mix design (BMD) method. VDOT has since committed to the implementation of the BMD method in an effort to improve asphalt mixture performance. Through a collaborative effort with industry, VDOT developed two special provisions for use with field trials that use the BMD method to specify as-designed mixture performance. This study documented and evaluated the field trials that were the first applications of these specifications in 2019 to design, produce, and place BMD asphalt mixtures in Virginia. The analyses addressed the application of the BMD concept, production variability, comparisons of mixtures, and differences in specimen test response with and without reheating of the loose mixture for fabrication. Nine mixtures were evaluated from the two field trials; the mixtures incorporated combinations of different reclaimed asphalt pavement (RAP) contents, two binder grades, two recycling agents, and two warm mix asphalt (WMA) additives. 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 a softer binder, WMA additives, 40% RAP, and recycling agents may be designed and produced to meet current BMD performance thresholds and current volumetric properties, gradation, and asphalt content requirements. The laboratory performance test results indicated that for some mixtures, WMA additives and a recycling agent may be expected to provide performance that is equal to or better than the performance of their counterpart mixtures containing only a WMA additive. In addition, results indicated that the evaluated asphalt mixtures containing 40% RAP and softer binders or a recycling agent can be expected to provide performance that is equal to or better than the performance of their counterpart mixtures with 30% RAP. The long-term field and laboratory performance of all of these mixtures needs to be evaluated to verify these early findings. The relationships between performance test results and mixture properties need further study, and improvements in test methods and criteria should be pursued. Based on the outcomes of the study, it is necessary to determine the precision estimates for the Cantabro and APA tests. In addition, the development of different performance criteria for the Cantabro and IDT-CT tests to be applied to non-reheated specimen testing may be necessary. The performance of multiple Cantabro and IDT-CT performance tests for each lot during production may be necessary such that an average test value can be used in BMD quality control, quality assurance, or acceptance practices, because of the variability in individual test results. In light of the lack of failing test results among the mixtures, APA tests may not need to be performed as frequently as Cantabro and IDT-CT tests during production, although this needs to be investigated further.
Aeronautical Engineering
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Author :
language : en
Publisher:
Release Date : 1983
Aeronautical Engineering written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1983 with Aeronautics categories.
A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA).
Nasa Sp
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Author :
language : en
Publisher:
Release Date : 1962
Nasa Sp written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1962 with Aeronautics categories.
Stone Matrix Asphalt
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Author : Krzysztof Blazejowski
language : pt
Publisher: CRC Press
Release Date : 2016-04-19
Stone Matrix Asphalt written by Krzysztof Blazejowski and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-04-19 with Technology & Engineering categories.
In the years since the development and subsequent success of Stone Matrix Asphalt (SMA), a plethora of articles have emerged, scattered throughout various publications. The time is right for a comprehensive resource that collects, examines, and organizes this information and makes it easily accessible. A compilation and distillation of the latest k
Proceedings Of The 5th International Symposium On Asphalt Pavements Environment Ape
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Author : Marco Pasetto
language : en
Publisher: Springer Nature
Release Date : 2019-08-29
Proceedings Of The 5th International Symposium On Asphalt Pavements Environment Ape written by Marco Pasetto and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-08-29 with Science categories.
This volume highlights the latest advances, innovations, and applications in the field of asphalt pavement technology, as presented by leading international researchers and engineers at the 5th International Symposium on Asphalt Pavements & Environment (ISAP 2019 APE Symposium), held in Padua, Italy on September 11-13, 2019. It covers a diverse range of topics concerning materials and technologies for asphalt pavements, designed for sustainability and environmental compatibility: sustainable pavement materials, marginal materials for asphalt pavements, pavement structures, testing methods and performance, maintenance and management methods, urban heat island mitigation, energy harvesting, 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 multidisciplinary collaboration among different specialists.