Evaluation Of Using Higher Percentages Of Recycled Asphalt Pavement In Asphalt Mixes In Virginia
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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.
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."--
Improved Mix Design Evaluation And Materials Management Practices For Hot Mix Asphalt With High Reclaimed Asphalt Pavement Content
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Author : Randy Clark West
language : en
Publisher: Transportation Research Board
Release Date : 2013
Improved Mix Design Evaluation And Materials Management Practices For Hot Mix Asphalt With High Reclaimed Asphalt Pavement Content written by Randy Clark West and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Pavements, Asphalt categories.
TRB's National Cooperative Highway Research Program (NCHRP) Report 752: Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content describes proposed revisions to the American Association of State Highway and Transportation Officials (AASHTO) R 35, Superpave Volumetric Design for Hot Mix Asphalt, and AASHTO M 323, Superpave Volumetric Mix Design, to accommodate the design of asphalt mixtures with high reclaimed asphalt pavement contents.
Assessing Increased Use Of Reclaimed Asphalt Pavement In Asphalt Mixtures
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Author : Harikrishnan Nair
language : en
Publisher:
Release Date : 2019
Assessing Increased Use Of Reclaimed Asphalt Pavement In Asphalt Mixtures written by Harikrishnan Nair and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Asphalt concrete categories.
In 2007, the Virginia Department of Transportation (VDOT) introduced specifications to allow asphalt surface mixtures to have up to 30% reclaimed asphalt pavement (RAP) without a change in the virgin binder grade. Since 2007, increasing material costs and a growing awareness of the quantity of RAP available for use have sparked interest in allowing asphalt mixtures to have a higher percentage of RAP. By 2013, VDOT had begun to consider the feasibility of allowing the use of surface mixtures with up to 45% RAP, and several trial sections were constructed containing mixtures with 20%, 30%, 40%, and 45% RAP for evaluation. This report presents the initial construction and laboratory performance data and discusses the lessons learned from these trials. In general, mixtures containing up to 45% RAP can be designed, produced, and constructed if proper procedures are followed and attention to detail is paid during design, production, and construction. As expected, all high RAP mixtures (i.e., mixtures containing >30% RAP) showed excellent rutting resistance based on laboratory testing. Laboratory performance testing indicated that the cracking resistance of high RAP mixtures depends on mixture and binder stiffness. The early field performance (2 to 3 years) of high RAP mixtures showed excellent rutting resistance and low values for the international roughness index, indicating smooth pavement. No premature cracks were observed in the high RAP sections. However, continued monitoring of these field sections is required to evaluate the long-term field performance.
Evaluation Of Recycled Asphaltic Concrete
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Author : Charles S. Hughes
language : en
Publisher:
Release Date : 1977
Evaluation Of Recycled Asphaltic Concrete written by Charles S. Hughes and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with Pavements, Asphalt categories.
This report describes a project in which approximately 6,200 tons (5,630 Mg) of asphaltic concrete were recycled through a conventional asphalt batch plant. During the construction of the project, a buildup of asphalt-coated fines occurred in the dryer and the dust collector. The buildup is thought to have been associated with the fineness and/or the high asphalt content of the recycled mix. To solve the problem, a change was made in the recycling process. The project was completed using a heat transfer method with mix proportions as high as 50% recycled material added to 50% virgin aggregate.
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.
Experimental Study Of Hot Recycled Asphalt Mixtures With High Percentages Of Reclaimed Asphalt Pavement And Different Recycling Agents
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Author : Jinhai Yan
language : en
Publisher:
Release Date : 2014
Experimental Study Of Hot Recycled Asphalt Mixtures With High Percentages Of Reclaimed Asphalt Pavement And Different Recycling Agents written by Jinhai Yan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Analysis of variance categories.
Hot recycled mixture has been widely used as binder course on highways in the Jiangsu Province, China. The objectives of this study were to evaluate recycled mixture's performance with different Reclaimed Asphalt Pavement (RAP) contents and recycling agents (RA). At first, optimum RA contents were determined according to asphalt blending charts based on penetration index. Secondly, the performance of recycled mixtures and control virgin asphalt mixture was evaluated based on retained stability, Tensile Strength Ratio (TSR), dynamic stability (DS), failure strain, and fatigue life. Thirdly, statistical significance on the basis of analysis of variance was evaluated as a function of RAP contents and RA type. The results indicated that adding RA could improve moisture stability, low temperature cracking resistance, while decreasing high temperature stability and strength performance of recycled mixture. Recycled asphalt mixture Sup-20 with RA has similar performance compared to virgin asphalt mixture Sup-20. The former has better moisture stability and high temperature stability than that of the latter, with a slight reduction in low temperature cracking and fatigue resistance. With a fixed RA-2, TSR, and failure strain of recycled mixes decreases, and DS first slightly decreases and then increases, while fatigue life first increases and then decreases with increasing RAP contents. The results indicated that the interface status and blending level between recycled asphalt and aggregate is variable due to the mixing process and material compositions, which results in the varied performance results of recycled mixes due to the different test temperatures, loading modes, and testing periods, etc. Furthermore, the results of analysis of variance are consistent with the experimental test results.
Functional Pavement Design
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Author : Sandra Erkens
language : en
Publisher: CRC Press
Release Date : 2016-10-14
Functional Pavement Design written by Sandra Erkens and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-10-14 with Technology & Engineering categories.
Functional Pavement Design is a collections of 186 papers from 27 different countries, which were presented at the 4th Chinese-European Workshops (CEW) on Functional Pavement Design (Delft, the Netherlands, 29 June-1 July 2016). The focus of the CEW series is on field tests, laboratory test methods and advanced analysis techniques, and cover analysis, material development and production, experimental characterization, design and construction of pavements. The main areas covered by the book include: - Flexible pavements - Pavement and bitumen - Pavement performance and LCCA - Pavement structures - Pavements and environment - Pavements and innovation - Rigid pavements - Safety - Traffic engineering Functional Pavement Design is for contributing to the establishment of a new generation of pavement design methodologies in which rational mechanics principles, advanced constitutive models and advanced material characterization techniques shall constitute the backbone of the design process. The book will be much of interest to professionals and academics in pavement engineering and related disciplines.
Evaluation Of High Percentage Recycled Asphalt Pavement As Base Course Materials
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Author : Mengqi Wu
language : en
Publisher:
Release Date : 2011
Evaluation Of High Percentage Recycled Asphalt Pavement As Base Course Materials written by Mengqi Wu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Asphalt categories.
Evaluation Of The Mmls3 For Accelerated Wearing Of Asphalt Pavement Mixtures Containing Carbonate Aggregates
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Author : Cristian Druta
language : en
Publisher:
Release Date : 2014
Evaluation Of The Mmls3 For Accelerated Wearing Of Asphalt Pavement Mixtures Containing Carbonate Aggregates written by Cristian Druta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Aggregates (Building materials) categories.
The purpose of this study was to develop an accelerated wearing protocol for assessing the susceptibility of asphalt surface mixtures to polishing. This was the second phase of the study. The first phase focused on assessing the characteristics of selected carbonate aggregates available in Virginia that are normally classified as polishing and thus not considered suitable for use in pavements except for those roads with an average daily traffic of less than 750 vehicles per day. The selection of aggregates used in pavements is critical in producing surfaces that will continue to provide good skid resistance through a lengthy service life.The specifications of the Virginia Department of Transportation (VDOT) call for non-polishing aggregate for use in most surface layers. The study was aimed at making use of locally available polishing aggregates that can reduce the cost of asphalt mixtures while maintaining satisfactory wearing and skid characteristics of the pavements. The objectives of the research were (1) to evaluate the polishing/wear features of mixtures containing limestone aggregate in the laboratory using an accelerated method; (2) to compare friction properties of the laboratory-polished specimens with actual pavement friction measurements; and (3) to compare friction properties of mixtures containing carbonate rock or blends with those of mixtures with non-carbonate rocks.The study included three types of aggregates, i.e., limestone, quartzite, and granite, and blends of these aggregates. The surface mixtures studied were conventional SM-9.5 and SM-12.5 mixtures containing various percentages of limestone, limestone recycled asphalt pavement, and limestone-granite/quartzite blends. The suggested test protocol to evaluate the polishing of asphalt concrete specimens prepared in the laboratory was developed using the third-scale model mobile load simulator (MMLS3). The MMLS3 is capable of applying realistic rolling wheel contact stresses similar to those on highways from the moving traffic.The skid resistance, friction, and texture of actual pavement surfaces and laboratory-fabricated specimens were measured after different polishing intervals. Skid resistance and frictional characteristics were measured by the British pendulum tester, dynamic friction tester, and locked-wheel skid tester; the circular texture meter was used to measure surface macrotexture. Results showed that the MMLS3 can be used to simulate traffic wearing of asphalt concrete specimens of different shapes and sizes in the laboratory including core specimens removed from existing pavements and that the BPT is effective in characterizing changes in friction on specimens that are subjected to simulated trafficking via the MMLS3. Further, test specimens should have a high initial macrotexture and mixtures should have good stability so that the wearing effects are focused on the aggregates. The study recommends that the Virginia Center for Transportation Innovation and Research (VCTIR) work with Virginia Tech and VDOTs western districts to design and conduct an experiment to explore a series of carbonate / non-carbonate aggregate blends for asphalt mixtures and that the mixture gradations be designed to prevent the absence of macrotexture from impacting the ability to measure the polish of the coarse aggregate structure of the experimental mixtures. VCTIR should purchase tires with different tread patterns and try them on the MMLS3 to evaluate the polishing rate of specimens in more detail.