Blending And Diffusion Of Recycled Asphalt Pavement And New Approach To Recycling Asphalt Shingle
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Blending And Diffusion Of Recycled Asphalt Pavement And New Approach To Recycling Asphalt Shingle
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Author : Yongjie Ding
language : en
Publisher:
Release Date : 2018
Blending And Diffusion Of Recycled Asphalt Pavement And New Approach To Recycling Asphalt Shingle written by Yongjie Ding and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Asphalt categories.
This study proposed a series of methods to investigate the blending and diffusion process of recycled asphalt mixtures using Fourier-transform infrared spectroscopy (FTIR), fluorescence microscopy and molecular dynamic simulation. A new approach to recycling asphalt shingles in which RAS binder was extracted by a mixed solvent with certain polarity and used as common asphalt binder was also developed. A new parameter, mean grey value (MGV), was derived from the fluorescence image and used to differentiate between recycled and virgin binders as well as their blends. The mobilization rate of plant-produced RAP mixtures was calculated on the basis of surface area proportion of aggregates with different size. Three types of asphalt mixtures, including one warm mix with foaming technology, two hot mixes with or without rejuvenator, were used to validate the proposed method. Two asphaltic models with three components including asphaltenes, resin, and oil were built with different components ratio to investigate the diffusion between virgin and aged binders. In an inter-diffusion model of virgin and aged binders, the diffusion coefficients of binders were not only determined by the diffusion ability itself, but also influenced by the properties of the diffusion acceptor. A new method was proposed to utilize fluorescence microscopy to determine the diffusion coefficient of aged RAP binder in recycled mixtures. The diffusion coefficient was determined by fitting the analytical solution to the laboratory concentration measurements. Comparison of the diffusion coefficient by the proposed method and that using the dynamic shear rheometer (DSR) method shows that the diffusion coefficient determined by fluorescence microscopy was of the same magnitude to, but slightly lower than that by DSR method. The RAS binder was extracted by a mixed solvent with certain polarity and used as common asphalt binder. The use of the mixed solvent of heptane and TCE with a certain proportion through the proposed method could prepare asphalt binder with desired properties. Results indicate that soft asphalt could not dissolve RAS binder at 170 °C. The binder blend of RAS binder and rejuvenator had a potential antiaging problem because an obvious loss of rejuvenator existed during the aging process.
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.
Sustainable Materials For Pavement Infrastructure
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Author : Louay Nadhim Mohammad
language : en
Publisher:
Release Date : 2019
Sustainable Materials For Pavement Infrastructure written by Louay Nadhim Mohammad and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with TECHNOLOGY & ENGINEERING categories.
As the price of liquid asphalt continuously climbs, methods are being sought to decrease material costs, which will also have less impact on ecological systems without compromising material or pavement performance. The use of recycled materials is one method that can replace a percentage of their virgin counterparts, thus reducing the negative impacts on the environment. Asphalt mixture performance is affected by the level of blending that occurs between aged and virgin asphalt binders. The interaction and compatibility of recycling agents (RAs) with recycled asphalt shingles (RAS) and reclaimed asphalt pavements (RAP) have not been thoroughly evaluated since the 1970s. To characterize laboratory mixture performance through their mechanistic and volumetric properties, a suite of tests was conducted to evaluate the low, intermediate, and high temperature performance of conventional asphalt mixtures and mixtures containing RAS and/or RAP with and without RAs. Also, the asphalt binders’ molecular structure was correlated with their cracking potential through binder fractionation. With respect to the mixes without RAs, results indicate that RAS binder does not fully blend with the virgin binder. The actual availability factor was found to range from 35 to 46%. Also shown was an improvement in rutting performance, with no adverse effects to intermediate temperature or low temperature performance because the mixtures are comprised of approximately 90% virgin asphalt. For mixtures containing RAs, a modified mixture design change was developed to improve blending between the aged and virgin asphalt binders. The actual availability factor was found to range from 50 to 100%. It was determined that RAs adversely affected the intermediate and low temperature properties of the mixtures studied due to the increase in the recycled binder content utilized within the mixture. In terms of low temperature properties, the use of soft binder performed similar to mixtures containing no RAs. The concentration of the high molecular RAS species exceeds 40% in which 25% of these are highly aggregated with apparent molecular weights approaching 100K. The use of RAs did not significantly dissociate the very high molecular weight species, and thus failed to improve mixture cracking resistance. In addition, Fourier-Transform Infrared Spectroscopy (FTIR) results were inconclusive.
Recycling Of Bituminous Pavements
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Author : Leonard Eugene Wood
language : en
Publisher: ASTM International
Release Date : 1978
Recycling Of Bituminous Pavements written by Leonard Eugene Wood and has been published by ASTM International this book supported file pdf, txt, epub, kindle and other format this book has been release on 1978 with Elasticity categories.
Selection Of Asphalt Recycling Methods And Recycled Asphalt Mixture Properties
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Author : Nicholas James Cerullo
language : en
Publisher:
Release Date : 2009
Selection Of Asphalt Recycling Methods And Recycled Asphalt Mixture Properties written by Nicholas James Cerullo and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Asphalt categories.
Multi Scale Approach To Design Sustainable Asphalt Paving Materials
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Author : Evan W. Holcombe
language : en
Publisher:
Release Date : 2017
Multi Scale Approach To Design Sustainable Asphalt Paving Materials written by Evan W. Holcombe and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Adhesion categories.
The continuous use of recycled material in asphalt pavement mixtures, specifically Reclaimed Asphalt Pavement (RAP), Recycled Asphalt Shingles (RAS) and Re-Refined Engine Oil Bottoms (REOB), have developed an increasing need to further evaluate the performance of these mixtures at the micro and macro-levels, as the use of such materials reduces cost of virgin materials and energy consumption. Although asphalt binder, including recycled or additive materials, may meet a desired performance grade (PG) using macro-scale tests, they may lack critical nano-mechanical properties that largely affect long-term performance, such as adhesion and diffusive efficiency between virgin and recycled binders. These commonly overlooked properties can correlate with performance behaviors such as fatigue and low temperature cracking during field performance.
Flexible Pavement Mixture Design Using Reclaimed Asphalt Concrete
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Author : Bernard F. Kallas
language : en
Publisher:
Release Date : 1984
Flexible Pavement Mixture Design Using Reclaimed Asphalt Concrete written by Bernard F. Kallas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1984 with Pavements, Asphalt categories.
Recommended Use Of Reclaimed Asphalt Pavement In The Superpave Mix Design Method
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Author : Rebecca McDaniel
language : en
Publisher:
Release Date : 2001
Recommended Use Of Reclaimed Asphalt Pavement In The Superpave Mix Design Method written by Rebecca McDaniel and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Pavements, Asphalt categories.
Application Of Reclaimed Asphalt Pavement And Recycled Asphalt Shingles In Hot Mix Asphalt
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Author :
language : en
Publisher:
Release Date : 2014
Application Of Reclaimed Asphalt Pavement And Recycled Asphalt Shingles In Hot Mix Asphalt written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Electronic book categories.
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.