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Evaluating The Effects Of Recycling Agents On Asphalt Mixtures With High Ras And Rap Binder Ratios
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Book Synopsis Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios by : Amy Epps Martin
Download or read book Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios written by Amy Epps Martin and published by . This book was released on 2020 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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."--
Book Synopsis Engineered Frameworks for Evaluating the Use of Recycling Agents in Surface Asphalt Mixtures for Virginia by : Jhony Habbouche
Download or read book Engineered Frameworks for Evaluating the Use of Recycling Agents in Surface Asphalt Mixtures for Virginia written by Jhony Habbouche and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Pavement Engineering by : Rajib B. Mallick
Download or read book Pavement Engineering written by Rajib B. Mallick and published by CRC Press. This book was released on 2022-12-30 with total page 819 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pavement Engineering: Principles and Practice examines a wide range of topics in asphalt and concrete pavements from soil preparation and structural design to life cycle costing and economic analysis. This updated Fourth Edition covers all concepts and practices of pavement engineering in terms of materials, design, and construction methods for both flexible and rigid pavements and includes the latest developments in recycling, sustainable pavement materials, and resilient infrastructure. New and updated topics include material characterization concepts and tests, pavement management concepts, probabilistic examples of life cycle cost analysis, end-of-life considerations, waste plastic in asphalt, pervious concrete, pavement monitoring instrumentation and data acquisition, and more. The latest updated references, state of the art reviews, and online resources have also been included.
Book Synopsis Plastic Waste for Sustainable Asphalt Roads by : Filippo Giustozzi
Download or read book Plastic Waste for Sustainable Asphalt Roads written by Filippo Giustozzi and published by Woodhead Publishing. This book was released on 2022-01-13 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: Waste polymers have been studied for various applications such as energy generation and biochemical production; however, their application in asphalt roads still poses some questions. Over the last decade, several studies have reported the utilization of waste plastics in roads using different methodologies and raw materials, but there is still significant inconsistency around this topic. What is the right methodology to recycle waste plastics for road applications? What is the correct type of waste plastics to be used in road applications? What environmental concerns could arise from the use of waste plastics in road applications? Plastic Waste for Sustainable Asphalt Roads covers the various processes and techniques for the utilization of waste plastics in asphalt mixes. The book discusses the various material properties and methodologies, effects of various methodologies, and combination of various polymers. It also provides information on the compatibility between bitumen and plastics, final asphalt performance, and environmental challenges. Discusses the processes and techniques for utilization of waste plastics in asphalt mixes. Features a life-cycle assessment of waste plastics in road surfaces and possible Environmental Product Declarations (EPD). Includes examples of on-field usage through various case studies.
Book Synopsis Evaluation of Asphalt Binder and Mixture Properties that Incorporate Reclaimed Asphalt Pavement by : Sang Ki Lee (M.S. in Engineering)
Download or read book Evaluation of Asphalt Binder and Mixture Properties that Incorporate Reclaimed Asphalt Pavement written by Sang Ki Lee (M.S. in Engineering) and published by . This book was released on 2018 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several private and public agencies are exploring ways in which the use of reclaimed asphalt pavement (RAP) can be increased in the construction of new pavements. However, such an increase must not come at the expense of reduced durability or life cycle cost. The use of RAP is often accompanied by some form of adjustment to the virgin binder that is being used. In Texas, the current practice of incorporating RAP is controlled by a simplified table that lists a substitute binder grade and recycled binder ratio (RBR) when RAP is incorporated in a mix. There are a few shortcomings with this simple approach of specifying a maximum ratio: (1) it does not address the potential difference in the quality of recycled binders from RAP, (2) it may result in the use of substituted binders with little or no polymer (elastomer) and (3) it does not account for the influence of recycling agents. The goal of this study was to evaluate the change in performance of binders and mixtures using different grades of virgin binder and percentages of RAP. Two different Job Mix Formulae (JMF) and corresponding materials were obtained from asphalt plants in the state of Texas. A test matrix was developed to evaluate binders and mixtures with different ratios of recycled binder to virgin binder and different ratios of RAP to virgin material, respectively. The results from this study show that addition of RAP or recycled binder (from RAP) results in an increase in stiffness and resistance to rutting, which was expected. However, the resistance to cracking showed mixed results. The test results also show that the properties of the recycled binder from RAP can vary significantly with source and have a drastic effect on the properties of the binder and mixture.
Book Synopsis Long-Term Effectiveness of Recycling Agents to Improve Performance Properties of Asphalt Concrete by : Mahsa Tofighian
Download or read book Long-Term Effectiveness of Recycling Agents to Improve Performance Properties of Asphalt Concrete written by Mahsa Tofighian and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recycled materials such as reclaimed asphalt pavement (RAP) have been incorporated into asphalt mixtures for many years. However, their usage has increased over time as they are seen as a way to reduce the cost of asphalt mixtures, save energy, and protect the environment. Similarly, there has been a growing focus on the utilization of recycled asphalt shingles (RAS) in asphalt mixtures, a pursuit undertaken by various state highway agencies. However, unless appropriate precautions are taken, as the proportion of RAP and RAS in the asphalt mixture is raised, the mixture becomes more brittle, leading to a higher risk of cracking and raveling in the asphalt pavement. Furthermore, the mixture becomes less workable and more challenging to compact in the field, increasing the potential for premature field failure. One strategy to incorporate more RAP and RAS into asphalt mixtures involves the use of specialized recycling agents (RAs), known as rejuvenating agents. Over time, asphalt mixtures undergo aging during construction and over the extended service life of asphalt pavements, resulting in the oxidation of the mix and the loss of a significant portion of the maltenes in the binder composition. Maltenes contribute to the softening effect of the binder, and these recycling agents, when used appropriately, are expected to compensate for this reduction in maltenes. The ultimate result of this rebalancing of components is the softening of the aged binder and an improvement in its resistance to cracking. This study investigates the long-term impact of bio-based and petroleum-based recycling agents (RA's) on recycled asphalt binders with varying levels of reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) content, specifically low (15%) and high (30%) RAP content and 0% and 5% RAS content. The rejuvenated binders underwent short-term and long-term aging through the use of a Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV), respectively. The performance characteristics of these modified binders at various aging stages were assessed using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The study revealed that all RA's used in this research maintained their effectiveness even after long-term aging, though the degree of effectiveness varied. Additionally, the results indicated that the petroleum-based RA required a higher dosage to achieve the same effect as the bio-based RA's. The findings from this research also demonstrated that when rejuvenators are added to mixtures with a high RAP content or a combination of RAP and RAS, the mixture's performance is enhanced in terms of low-temperature cracking and fatigue cracking. Nevertheless, it is crucial to extend this work to field pilot projects to ensure the effective application of these rejuvenating products.
Book Synopsis Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content by : Randy Clark West
Download or read book Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content written by Randy Clark West and published by Transportation Research Board. This book was released on 2013 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Blending Issues of Hot and Warm Mix Asphalt Containing Recycled Asphalt Pavement and Recycled Asphalt Shingle by : Sheng Zhao (Writer on pavements)
Download or read book Blending Issues of Hot and Warm Mix Asphalt Containing Recycled Asphalt Pavement and Recycled Asphalt Shingle written by Sheng Zhao (Writer on pavements) and published by . This book was released on 2014 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current tendency in paving industry is to increase the use of recycled asphalt pavement (RAP) and recycled asphalt shingle (RAS). However, one of the reasons that limit the high recycled amount is the unknown blending between virgin and RAP/RAS binders. A series of studies were conducted in this dissertation to address blending issues in warm mix asphalt (WMA) and hot mix asphalt (HMA) containing RAP and RAS, in terms of evaluation of recycled binder mobilization, binder homogeneity and WMA effects on blending. Partial blending was observed in RAS mixtures and the most efficient blending occurred at approximately 5% RAS by weight. Increasing time led to a better RAS binder mobilization, while aggregate size and temperature in a certain range showed limited effects. A new parameter derived from gel permeation chromatography (GPC), large molecular size percentage [LMS(%)] related to binder molecular weight distribution, was developed to differentiate virgin and RAP/RAS binders as well as their blends, based on which a method was developed to quantify the recycled binder mobilization rate. A two-layer model based on atomic force microscopy (AFM) scanning was developed to evaluate RAS and virgin binder blending. The two binders were found to be “mixing” but not “blending” in a mixing zone of 25 to 30 micrometer. Staged extraction method used to evaluate asphalt binder homogeneity was validated with trichloroethylene (TCE) as the most effective solvent. A non-equal-time staged extraction method was proposed, in conjunction with LMS(%), to quantify binder homogenization after mechanical mixing and diffusion. Different blending scenarios of RAP/RAS mixes were proposed and validated. It was found that diffusion could be accomplished within mixture storage time for both WMA and HMA containing RAP, while blending in RAS mix was limited. WMA additives yielded mixes with higher blending ratios than control mix produced at 135oC, but lower than hot mix produced at 165oC. Laboratory foaming yielded a higher blending ratio, indicating foamed WMA may improve blending. Rutting might still be a concern for WMA-high RAP mixtures while fatigue concern may not exist. WMA-high RAP mixtures showed satisfactory moisture resistance. Blending effects on performance still needs further investigation.
Book Synopsis Asphalt Paving Technology 2013 by : Eugene Skok
Download or read book Asphalt Paving Technology 2013 written by Eugene Skok and published by DEStech Publications, Inc. This book was released on 2014-02-04 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: New developments in mixing, testing, modeling Research findings on sustainable asphalt technology Bitumen use and specifications in Europe Fully-searchable text on accompanying CD-ROM Asphalt Paving Technology 2013, a series volume, contains 26 original research papers devoted to the formulation, chemistry, mixing, modeling, testing and optimization of asphalt—with applications to highway and infrastructure engineering. Written by leading civil and structural engineers from universities and government agencies around the world, the book offers information for designing and producing higher-quality asphalt. Selected keywords: photocatalytic asphalt; fatigue loading; skid-resistance; low-temperature cracking software; long-term aging; fracture properties; moisture damage; RAP; rejuvenators; binders; flexible pavement; healing. The CD-ROM displays figures and illustrations in articles in full color along with a title screen and main menu screen. Each user can link to all papers from the Table of Contents and Author Index and also link to papers and front matter by using the global bookmarks which allow navigation of the entire CD-ROM from every article. Search features on the CD-ROM can be by full text including all key words, article title, author name, and session title. The CD-ROM has Autorun feature for Windows 2000 with Service Pack 4 or higher products along with the program for Adobe Acrobat Reader with Search 11.0. One year of technical support is included with your purchase of this product.
Book Synopsis Fundamental Evaluation of the Interaction Between RAS/RAP and Virgin Asphalt Binders by : Munir D. Nazzal
Download or read book Fundamental Evaluation of the Interaction Between RAS/RAP and Virgin Asphalt Binders written by Munir D. Nazzal and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive laboratory testing program was conducted in this research project to examine the blending between reclaimed asphalt pavement (RAP)/recycled asphalt shingles (RAS) and virgin asphalt binders and to evaluate the factors that may affect fatigue and low-temperature cracking as well as moisture-induced damage in asphalt mixtures prepared using these materials. This project included two parts: a binder study and a mixture study. In the binder study, atomic force microscopy (AFM) was utilized to characterize the micromechanical properties of the interfacial zone that develops between the RAP/RAS binders and the virgin asphalt binders. Three virgin asphalt binders with different performance grades (PG 58-28, PG 64-28, and PG 64-22), three RAP sources, as well as manufacturing waste and tear-off RAS were used in this project. A new sample-preparation procedure was developed to simulate the blending between the RAS/RAP and the virgin asphalt binders that occurs during asphalt mixture production. The micro-structure, stiffness and the adhesive properties along the blending zone were evaluated for different combinations of RAP/RAS binders and virgin binders. In the mixture study, several asphalt mixtures were used to evaluate the effect of the incorporation of RAP and/or RAS on the mix performance, including a control mixture (no RAP or RAS), a mixture containing 30% RAP, a mixture containing 5% tear-off RAS, and a mixture containing 20% RAP and 3% tear-off RAS. All mixtures were designed to meet ODOT specifications for Item 442 (Superpave) Type A for heavy traffic intermediate course asphalt mixes. The resistance of the asphalt mixtures to fatigue cracking was evaluated using the semi-circular bend (SCB) and the indirect tensile strength (IDT) tests. The SCB test was performed using the Illinois Method and the Louisiana Method. In addition the potential for low-temperature cracking was evaluated using the asphalt concrete cracking device (ACCD), and the susceptibility of the asphalt mixtures to moisture-induced damage was evaluated using the AASHTO T 283 (modified Lottman) test. The AFM test results indicated that blending occurred to a varying degree between the RAP binders and the virgin binders for all RAP-virgin binder combinations. The average modulus of the blending zone depended on the properties of the RAP and the virgin binders. For all binders, a reduction in the adhesive bonding energy was also observed in the blending zone due to the presence of RAP. However, the adhesive properties of the blending zone were significantly higher than those in the RAP binders. Statistical analysis also indicated that the stiffness of the interface blending zone is affected by the properties of the RAP and virgin asphalt binders, while the adhesive properties of the interface blending zone is primarily affected by those of virgin binder used. A linear regression model was developed to predict the modulus and adhesive bonding energy of the blending zone in terms of RAP and virgin binder properties. The validation of the regression models suggested that these models can serve as a viable tool in selecting the virgin binder to be used in a RAP mixture based on the properties of the RAP binder. Finally, the AFM imaging and force spectroscopy experiments revealed very limited to no blending between manufacturing waste or tear-off RAS materials and the virgin binders considered. The asphalt mixture test results also showed that the use of tear-off RAS in intermediate asphalt mixes significantly reduced their resistance to low-temperature and fatigue cracking as well as moisture damage, which can be attributed to the limited blending observed in the AFM experiments between the RAS and the virgin asphalt binders.
Book Synopsis Evaluating the Effect of High RAP Content on Asphalt Mixtures and Binders Fatigue Behavior by : Umme Amina Mannan
Download or read book Evaluating the Effect of High RAP Content on Asphalt Mixtures and Binders Fatigue Behavior written by Umme Amina Mannan and published by . This book was released on 2018 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the main concerns with the application of reclaimed asphalt pavement (RAP) in the asphalt concrete pavement is fatigue cracking due to the stiffness increase with the addition of aged and stiff RAP binder. The purpose of this study is to evaluate fatigue performance of asphalt binder and mixtures with different RAP percentages (0, 15, 25, 35 and 40 %). Among these, 35 and 40 % RAP mixes are considered as high RAP content. This study describes the results of laboratory fatigue response of asphalt mixtures and extracted binders containing RAP to define the effect of RAP on the fatigue performance. To achieve this objective, mixes and binders were tested using the beam fatigue test and the time-sweep test, respectively. Test results were analyzed using two different fatigue approaches, reduction in stiffness and dissipated energy criteria. Results showed that a higher initial stiffness and initial dissipated energy initiate the fatigue failure faster. Since both binders and mixes show an increase in the stiffness and energy consumed per loading cycle with the addition of RAP, resulting mixes containing higher RAP have a very short fatigue life. Also, the fatigue endurance limit decreases drastically with the addition of RAP in the mix. The results comparing two different RAP sources showed that the RAP source has more prominent effect on the mix fatigue performance than the binder fatigue performance. Finally, the traditional fatigue life prediction model is modified to incorporate the effect of RAP in the fatigue equation. The modified regression model predicted reasonable fatigue life of the mixture with a coefficient of determination (R2) close to 1. The measured and predicted fatigue life results were found close to each other for both mix and binder containing RAP.
Book Synopsis Research on High-RAP Mixtures with Rejuvenator-field Implementation by : Nitish R. Bastola
Download or read book Research on High-RAP Mixtures with Rejuvenator-field Implementation written by Nitish R. Bastola and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of Rejuvenating Agents (RAs), as Recycled Asphalt Pavement (RAP) modifiers, has been increasing over the past years. However, the field performance of asphalt mixtures containing high-RAP materials and modified with RAs has raised some concerns regarding the long-term performance of RAs. This study evaluated the laboratory and field performance of high-RAP mixtures with and without bio-oil RA. Three sets of plant-produced specimens were collected: 1) laboratory-compacted; 2) field-compacted and cored after paving; and 3) field-compacted and cored after one and two years. The Hamburg Wheel Tracking (HWT) test was used to evaluate the specimens' resistance to rutting and moisture damage. The Semi-Circular Bending (SCB) fracture test was performed to examine the specimens' resistance to cracking. The results showed that using the bio-oil RA resulted in an increase in cracking resistance and a decrease in rutting and moisture damage resistance of the RAP-blended mixtures compacted in the laboratory. However, after one and two years of exposure to the environmental conditions and traffic loads, the effect of RA on moisture and rutting susceptibility of the mixtures reduced. The cracking resistance of specimens, estimated by Flexibility Index (FI) and Cracking Resistance Index (CRI), and Tukey's Honestly Significant Difference (HSD) test results implied that the bio-oil RA used in this study could not provide long-term improvement for the RAP-blended mixtures in the laboratory-aging and field-aging conditions. The field performance observations showed that the use of the bio-oil RA in the second layer might have indirectly resulted in more cracks (fatigue and thermal) and ruts in the surface layer.(Page i)
Book Synopsis Evaluation of Stone-Matrix Asphalt Mixtures Containing Recycled Asphalt Shingles (RAS) by : Stacey D. Diefenderfer
Download or read book Evaluation of Stone-Matrix Asphalt Mixtures Containing Recycled Asphalt Shingles (RAS) written by Stacey D. Diefenderfer and published by . This book was released on 2017 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, there has been increased interest in the use of reclaimed material in asphalt mixtures. The use of recycled asphalt shingles (RAS) has been of interest because of the high asphalt content, although this asphalt is considerably stiffer than that typically used in paving mixtures. The Virginia Department of Transportation has specifications allowing the use of post-manufacturing waste and post-consumer RAS, although use has been limited. In addition, the specifications do not provide for the use of RAS in stone matrix asphalt (SMA). In response to producer requests for RAS use in SMA, this study investigated the use of RAS in SMA mixtures in VDOTs Salem and Staunton districts. Mixtures were sampled during production, characterized, and evaluated using a suite of laboratory tests including dynamic modulus, flow number, rut depth, and bending beam fatigue. Test results indicated that, as expected, the inclusion of RAS appears to improve high temperature / low frequency modulus values and rutting resistance. The inclusion of RAS had mixed effects on the mixture performance in laboratory fatigue testing. Binder testing on one set of mixtures indicated that the virgin binder grade may significantly affect the degree of blending of the RAS binder. In addition, extracted binder Tc values indicated that the inclusion of either RAP or RAS may have adverse impacts on cracking susceptibility. These findings should be validated with field performance and additional mixtures. The study recommends that the Virginia Department of Transportation not change specifications to allow RAS in SMA at this time. In specific situations, the use of RAS in SMA should be approached judiciously, as when effectively located and properly designed, produced, and placed. RAS mixtures have the potential for improved rutting performance, although impacts on cracking performance must be carefully assessed.
Book Synopsis Evaluation of the Combined Effects of Reclaimed Asphalt Pavement (RAP), Reclaimed Asphalt Shingles (RAS), and Different Virgin Binder Sources on the Performance of Blended Binders for Mixes with Higher Percentages of RAP and RAS by : M. Z. Alavi
Download or read book Evaluation of the Combined Effects of Reclaimed Asphalt Pavement (RAP), Reclaimed Asphalt Shingles (RAS), and Different Virgin Binder Sources on the Performance of Blended Binders for Mixes with Higher Percentages of RAP and RAS written by M. Z. Alavi and published by . This book was released on 2015 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Study of Hot Recycled Asphalt Mixtures with High Percentages of Reclaimed Asphalt Pavement and Different Recycling Agents by : Jinhai Yan
Download or read book Experimental Study of Hot Recycled Asphalt Mixtures with High Percentages of Reclaimed Asphalt Pavement and Different Recycling Agents written by Jinhai Yan and published by . This book was released on 2014 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Evaluation of Long-Term Performance of High Recycled Asphalt Pavement (RAP) Mixes and Development of Models for RAP Binder Contribution and Aging by : Logan Dale Cantrell
Download or read book Evaluation of Long-Term Performance of High Recycled Asphalt Pavement (RAP) Mixes and Development of Models for RAP Binder Contribution and Aging written by Logan Dale Cantrell and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recycled asphalt pavement (RAP) is one of the most recycled materials in the United States. It provides many environmental and economic benefits, but RAP usage has stagnated recently. The advancement in rejuvenators and performance testing renews the ability to increase RAP levels and address cracking concerns. This study investigated the use of RAP in asphalt concrete and if it could be increased beyond current limits without adversely affecting long-term performance. These results provide evidence and tools for increasing RAP both in the mix design and production stages. Additionally, the models developed can make implementing performance testing in production much more feasible. Field constructability and performance were first evaluated to ensure current high RAP (HR) mixes are performing adequately. This systematic approach found that HR mixes performed equal or better than low RAP (LR) typical mixes with lower density deviation and less longitudinal cracking. Then, super high RAP (SHR) mixes, with RAP levels up to 100%, were designed using current WSDOT volumetric design standards. SHR mixes were statistically similar in rutting and cracking performance to typical 20% RAP mixes except for polymer modified binder mixes with RAP levels above 80% due to an overall reduction in polymer and degradation of polymer cross-linking. Cracking performance could be improved with the slight addition of a virgin binder. With SHR mixes showing potential, models based on mix mechanics were developed to aid in implementation. First, a model to predict RAP binder contribution (PRBC) was developed based on mix performance testing. Lab results showed that the mix with a neat virgin binder with softer RAP contributed more than the modified virgin binder with stiffer RAP. The model was then adjusted for use with plant mixes and showed HR mixes, and V binders with more PRBC than LR mixes and H binders. An aging model was then developed to predict cracking performance as a mix aged. Next, a logarithmic-based model was chosen to predict aged CTIndex results, which characterizes both oxidative aging and polymer degradation. Finally, a 3D model was created to predict the effects of both RAP addition and aging on CTIndex samples.
Book Synopsis Sustainability Assessment of Recycled Asphalt Mixtures in Texas by : Reza Saeedzadeh
Download or read book Sustainability Assessment of Recycled Asphalt Mixtures in Texas written by Reza Saeedzadeh and published by . This book was released on 2016 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: The pavement practitioners use more recycled materials in asphalt mixtures in order to compensate for the high price of petroleum products and save the limited resources of virgin materials. Reclaimed Asphalt Pavement (RAP) and Recycled Asphalt Shingles (RAS) have been in wide use in asphalt mixtures for several decades. Public perception on the utilization of recycled materials is that the mixtures become more cost effective and more environmental friendly. This is true when the initial stage of construction of pavements is assessed. However, a mixture that costs less and/or burdens the environment less at the beginning may require more frequent rehabilitation because of poor performance. Therefore, in order to have a comprehensive idea of the sustainability of a mixture, its entire life cycle should be evaluated. The objective of this research was to assess the sustainability of three recycled asphalt mixtures and of a mix not containing recycled materials. The recycled mixtures were labeled as "High RAP", "RAP&RAS-WMA" and "BMD". The "High RAP" mixture had 19 percent fractionated RAP. The "RAP&RAS-WMA" had 15 percent RAP and 3 percent RAS while the production technology was WMA. The "BMD" mixture had 15 percent RAP, 3 percent RAS and slightly higher binder content. The virgin mixture was "Type D" which is a common dense-graded mixture in Texas. Twelve pavement sections were constructed from these four mixtures to evaluate their resistance to rutting, fatigue cracking and reflection cracking. The Accelerated Pavement Testing machine of the University of Texas at Arlington was employed to perform the full-scale testing. The results of field sections were then utilized to determine the service life of the mixtures for initial construction and subsequent required overlays. The life cycle environmental burden and cost of each mixture were also calculated. Field results suggested that rutting is not a concern for these mixtures. The virgin control mixture had the second best performance in resistance to both fatigue cracking and reflection cracking. The life cycle environmental assessment of mixtures showed that the "BMD" mixture had the least environmental impacts and was followed by the "Type D", the "RAP&RAS-WMA" and the "High RAP" mixtures. The same ranking of mixtures was observed in life cycle cost analysis. Among different construction phases, the "Materials Production" phase had the highest energy consumption and carbon dioxide emission, mainly due to the bitumen production process.
