Evaluation Of The Effect Of Homogeneity Of The Asphalt Binder On Performance Of A Recycled Mix
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Evaluation Of The Effect Of Homogeneity Of The Asphalt Binder On Performance Of A Recycled Mix
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Author :
language : en
Publisher:
Release Date : 2019
Evaluation Of The Effect Of Homogeneity Of The Asphalt Binder On Performance Of A Recycled Mix written by 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 categories.
The road to sustainability passes through the process of recycling a greater amount of asphalt pavement. Inclusion of additional amounts of reclaimed asphalt pavement (RAP) in new mixes has become a prominent method to promote sustainability. This research addresses some of the challenges related to high RAP content mixes. Among the factors considered are the impact of rejuvenator diffusion on binder stiffness, stiffness gradient, performance grade, homogeneity, and ultimately, their effects on mix performance.
Blending Issues Of Hot And Warm Mix Asphalt Containing Recycled Asphalt Pavement And Recycled Asphalt Shingle
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Author : Sheng Zhao (Writer on pavements)
language : en
Publisher:
Release Date : 2014
Blending Issues Of Hot And Warm Mix Asphalt Containing Recycled Asphalt Pavement And Recycled Asphalt Shingle written by Sheng Zhao (Writer on pavements) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Asphalt categories.
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.
Effects Of Laboratory Mixing Methods And Rap Materials On Performance Of Hot Recycled Asphalt Mixtures
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Author : Viết Hưng Nguyễn
language : en
Publisher:
Release Date : 2009
Effects Of Laboratory Mixing Methods And Rap Materials On Performance Of Hot Recycled Asphalt Mixtures written by Viết Hưng Nguyễn and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The primary work reported in this thesis is concerned mainly with the effects of different mixing methods and RAP materials on homogeneity and mechanical properties of hot recycled asphalt mixtures. The recycled asphalt mixture conforms to the requirement of BS 4987-1 (2005) for dense bitumen macadam size 10 mm (DBM 10 mm). The proportion of RAP in the recycled mixture is 40%. RAP materials are artificially aged and processed in the laboratory to prevent the variability of RAP gradation, bitumen content, and the origin. Laboratory RAP is also used to assure that every single RAP particle is an agglomerate of RAP aggregate and binder. The mixing procedures include Black Rock (BR), Complete Blending (CB), the SHRP procedure, and a newly developed field simulation method (FS). The primary difference between these methods is the mixing mechanism. The BR case implies the situation in which there is completely no interaction between RAP and virgin binder. On the contrary, RAP and virgin binder are fully interacted in the CB case. The mixing procedures for BR and CB cases conform to those for conventional asphalt mixtures. However, the bitumen for BR case is pure virgin bitumen. In addition, the bitumen for CB is the blend between RAP and virgin binder. The RAP/virgin binder proportion is 4/6. In the SHRP method, RAP is preheated at 110oC for two hours before being mixed with virgin aggregate and binder for 2 minutes at 130oC. In the FS method on the contrary, the mixing procedure duplicates what occurs in the asphalt mixing plant. RAP is mixed with superheated virgin aggregate (215oC) for different durations before this combination is blended with virgin bitumen for 2 minutes at 130oC. The RAP/superheated virgin aggregate mixing duration starts from short mixing time where RAP still exists at approximately original size and gradually increases until the change in RAP lump size is insignificant. Depending on the size of RAP used, RAP/superheated virgin aggregate mixing duration varies from 1 to 8 minutes. The homogeneity of hot recycled asphalt mixture is examined by using virgin binder with a different colour from that of RAP binder. The colour of virgin binder is obtained by mixing clear binder (Shell Mexphalt C 160/220 Pen) with iron oxide pigment. The proportion of pigment is 10% by weight of the binder making this binder red. The use of virgin binder with different colour from that of RAP binder helps to clearly differentiate the locations of RAP and virgin materials. Surfaces of slices cut from compacted recycled specimens are photographed by digital camera. The analysis of these surfaces in vertical order allows the locations of RAP material to be qualitatively identified in a 3D manner. Stiffness modulus values of samples for homogeneity assessment are also determined by indirect tensile stiffness test. The stiffness test is carried out in four directions along the circumference of each specimen with 45o angular increments. The experimental results show that the stiffness measurement in four directions can indicate the heterogeneity of recycled mixture. The variation in stiffness values in different measured directions will be substantial for heterogeneous mixtures and minor in the case where recycled mixtures are homogeneous. The results indicate there are mutual relations between mixing effort, homogeneity, and stiffness values of recycled asphalt mixtures. The longer mixing time will enhance the homogeneity and reduce the variation in stiffness values of recycled mixture. In addition, as more RAP and virgin binder are incorporated, the stiffness values of recycled mixture generally increase once the mixing time is extended. As the clear binder is dyed red by 10% by weight of iron oxide, the proportion of the pigment certainly alters the flow characteristic of binder. This might affect the mixing process and rejuvenating effect between virgin and aged binder. Therefore, the effects of mixing methods and RAP sizes on mechanical performance of hot recycled asphalt mixtures are further investigated using normal straight run bitumen 160/220 Pen as virgin binder. The assessment indicators include stiffness modulus, resistance to fatigue damage, and resistance to permanent deformation. The experimental results indicate that the conventional laboratory mixing method (SHRP) tends to overestimate the mechanical properties of recycled asphalt mixture. The long RAP preheating time that never exists in the industry coincidentally enhances the reaction between RAP and virgin binder. The long RAP preheating time also slightly alters the properties of RAP binder. For the FS method, the increase in mixing duration significantly improves the homogeneity level of recycled mixtures. The homogeneity level is also substantially affected by the size of RAP material. For the same mixing effort, the mixtures comprised of small RAP are generally more homogeneous than those made from larger RAP. The more homogeneous the mixture, the more interaction between RAP and virgin binder. Therefore, recycled mixtures become stiffer and have better resistance to permanent deformation and fatigue failure. A slightly linear increase in stiffness can result in an exponential increase in fatigue life of the recycled mixture. The mechanical properties including stiffness modulus, resistance to fatigue damage, and resistance to permanent deformation of hot recycled asphalt mixtures are not similar to those of the BR or CB mixtures, even at the favourable condition where RAP is preheated for 2 hours at 110oC in the SHRP method and 8 minutes mixing duration in the FS method. This implies that RAP does not act as Black Rock. In addition, the assumption that RAP and virgin binder are fully blended also never exists in the recycled asphalt production process.
Proceedings Of The 10th International Conference On Civil Engineering
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Author : Guangliang Feng
language : en
Publisher: Springer Nature
Release Date :
Proceedings Of The 10th International Conference On Civil Engineering written by Guangliang Feng and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on with categories.
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."--
Performance Evaluation Of Warm Mix Recycled Asphalt Binders After Long Term Aging
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Author : Qiang Li
language : en
Publisher:
Release Date : 2019
Performance Evaluation Of Warm Mix Recycled Asphalt Binders After Long Term Aging written by Qiang Li 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 emulsion mixtures categories.
This study evaluates the pavement performance evolution of warm-mix recycled asphalt binders during the secondary service period. Warm-mix recycled asphalt binders with various long-term aging levels and recycling plans were produced by the laboratory simulation method. Conventional physical properties tests, the dynamic shear rheometer test, and the bending beam rheometer test were conducted to measure the performance of recycled binders. Effects of the aging level and recycling plan on the resistance to rutting, fatigue cracking, and low temperature cracking were investigated by statistical methods. It was found that after secondary long-term aging, recycled binders are more resistant to rutting, while they are less resistant to fatigue and low temperature cracking. The modified aging kinetic model can be used to accurately characterize the effect of secondary aging time on rutting or fatigue factors for recycled binders. The resistance of aged binders to fatigue and low temperature cracking is obviously improved by adding the warm mix asphalt additive. By comparison, using styrene butadiene rubber latex enhances the binder performance in almost all aspects. The aging level has a more significant effect than the recycling plan for all performance parameters.
Plastic Waste For Sustainable Asphalt Roads
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Author : Filippo Giustozzi
language : en
Publisher: Woodhead Publishing
Release Date : 2022-01-13
Plastic Waste For Sustainable Asphalt Roads written by Filippo Giustozzi and has been published by Woodhead Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-01-13 with Technology & Engineering categories.
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.
Investigation Of Binder Rheology And Performance Outcomes Of Recycled Hot Mix Asphalt Using Different Rejuvenation Agents
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Author : Kerry Jean King
language : en
Publisher:
Release Date : 2015
Investigation Of Binder Rheology And Performance Outcomes Of Recycled Hot Mix Asphalt Using Different Rejuvenation Agents written by Kerry Jean King and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Pavements categories.
The research presented in this thesis investigated the effect of various rejuvenation agents on the performance of hot-mix asphalt (HMA) surfacing mixes containing high levels of recycled asphalt pavement (RAP) material (30%). The research aimed to develop testing methodologies for evaluating the mechanical performance properties of HMA mixes and for the characterisation of extracted binder properties. The methodologies were used determine the effects of various rejuvenators on the mechanical performance properties and binder properties fundamental to the long-term performance of pavement surfaces. A testing methodology was developed to investigate the performance properties of five HMA mixes including four mixes that were rejuvenated using different rejuvenation agents and one control. The mechanical testing methodology provided a comprehensive assessment of mix properties that are fundamental to the long-term performance of recycled pavements. A methodology for the characterisation of extracted binders was developed to evaluate properties that had a significant effect on the performance of the binder and therefore the overall mix. The binder properties were compared to results obtained from mechanical performance tests to establish a relationship between binder rejuvenation and performance observations. The results obtained from mechanical testing demonstrated that the cracking resistance of recycled mixes could be significantly improved through the use of rejuvenation agents. Rejuvenation also decreased the stiffness of the mix and had a negative effect on the resistance of a mix to permanent deformation. From the characterisation of the binder, it was found that rejuvenation agents altered the rheological properties of the binder but did not have a notable effect on chemical composition. The rheological performance parameters of the binder correlated to the mix performance observed from mechanical tests. Overall this research has shown that rejuvenation agents can be utilised to enhance the performance of recycled mixes by restoring binder properties.
Evaluation Of The Effects Of Asphalt Binder On The Properties Of Hot Mix Asphalt At Intermediate Temperatures
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Author : Haifang Wen
language : en
Publisher:
Release Date : 2011
Evaluation Of The Effects Of Asphalt Binder On The Properties Of Hot Mix Asphalt At Intermediate Temperatures written by Haifang Wen 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.
The asphalt binder is an essential component of asphaltic mixtures. The performance of an asphaltic mixture is directly related to mechanical characteristics of the binder. With the development of new material characterization methods for both asphalt binder and asphaltic mixture, there is a need to re-evaluate the relationship between the properties of binders and asphaltic mixtures such that a proper understanding and selection of an asphalt binder can be made to improve the performance of an asphaltic mixture. In this study, the effects of asphalt binder properties on asphaltic mixtures at intermediate temperatures were evaluated based on recent developments on material characterization methods for both binder and asphaltic mixture. Five asphalt binders and five asphalt mixtures containing these binders with one aggregate were tested. Four of the binders were based on a modification of a base binder with different techniques. Complex shear modulus and monotonic constant shear-rate tests were conducted on asphalt binders, whereas dynamic modulus and indirect tensile strength tests were conducted on the mixtures. The effects of modification techniques on the properties of asphalt binders and the relationships between the properties of binders and asphaltic mixtures were evaluated in this study.
Evaluation Of Asphalt Binder And Mixture Properties That Incorporate Reclaimed Asphalt Pavement
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Author : Sang Ki Lee (M.S. in Engineering)
language : en
Publisher:
Release Date : 2018
Evaluation Of Asphalt Binder And Mixture Properties That Incorporate Reclaimed Asphalt Pavement written by Sang Ki Lee (M.S. in Engineering) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
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.