Investigation of the oxidation ageing of RAP asphalt blend binders and mixtures
TL;DR: In this paper, the authors evaluate the oxidation ageing properties of asphalt blends and mixtures combined with various percentages of RAP and SBS-modified binder, rejuvenator and neat binder.
Abstract: This study evaluates the oxidation ageing properties of asphalt blends and mixtures combined with various percentages of RAP and SBS-modified binder, rejuvenator and neat binder. Four ageing method...
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TL;DR: In this paper , an ab initio molecular dynamics simulations and density functional theory calculations based on the quantum chemistry framework were conducted to explore the reaction pathway and thermodynamic driving force of asphaltene aging.
16 citations
TL;DR: In this article, a ternary composite carbon nitride modifier (CN-Bi-Tr-DC) with excellent compatibility with asphalt binder was prepared, and the results showed that the long organic chains were successfully grafted onto the surface of the Ternary Composite Carbon Nitride modifier.
6 citations
TL;DR: In this article , a three-layer model of oxygen-asphalt-aggregate was generated to explore the molecular mechanism of gradient aging, and the aging differences of asphalt films in the vertical aggregate direction were investigated.
5 citations
TL;DR: In this paper , a three-layer system was established in which the two sides are asphalt molecules and the middle is a 30 Å vacuum layer, and the results showed that the disappearance of cracks during the self-healing process was the combined effect of model volume compression and asphalt molecule stretching.
Abstract: In order to accurately describe the self-healing behavior of recycled asphalt prepared by residue oil of straw liquefaction (ROSL), five ROSL contents of 2%, 4%, 6%, 10%, and 15% were added to the aged asphalt to represent the recycled asphalt and are denoted as ROSL-2, ROSL-4, ROSL-6, ROSL-10, and ROSL-15, respectively. Molecular simulation was used to simulate the healing behavior of nano cracks. A three-layer system was established in which the two sides are asphalt molecules and the middle is a 30 Å vacuum layer. The vacuum layer represented the internal nano cracks in the asphalt. The results show that the disappearance of cracks during the self-healing process was the result of the combined effect of model volume compression and asphalt molecule stretching. Self-healing is mainly affected by the van der Waals forces between the molecules. The self-healing rate of recycled asphalt is closely related to the content of ROSL, the higher the ROSL content, the greater the diffusion coefficient, which is more conducive to asphalt self-healing. However, as the time for ROSL-10 and ROSL-15 to reach the equilibrium distribution of relative concentration and density stability is basically the same, and the diffusion coefficient of ROSL-10 is basically the same as that of virgin asphalt, the optimal content of the ROSL is recommended to be 10%.
4 citations
01 Sep 2021
TL;DR: In this article, the effectiveness of using a relatively new plant-based RAg produced from biofuel residue in a low-carbon footprint process when used in asphalt binder blends containing a high amount of RAP was investigated.
Abstract: Protecting environment, conserving natural resources by recycling and replacing non-renewable materials with renewable ones, reducing material cost, and utilizing sustainable processes are actively pursued by asphalt industry. Consistent with those efforts, Recycling Agents (RAg) with different technologies have been introduced which allow using high amounts of Reclaimed Asphalt Pavement (RAP) in construction of new pavements. RAgs, depending on their type and chemical composition, affect the mechanical properties of the asphalt binders differently. This study was undertaken to characterize effectiveness of using a relatively new plant-based RAg produced from biofuel residue in a low-carbon footprint process when used in asphalt binder blends containing a high amount of RAP. Effects of using different amounts of RAg, namely 0, 4, 6, and 8% (by binder weight) incorporated in a blend of a PG 58-28 containing 30% laboratory-simulated RAP binder (RAPsb) on binder blends’ rheological properties were studied by testing them in a dynamic shear rheometer and a bending beam rheometer and by conducting Multiple Stress Creep Recovery (MSCR) tests. In addition, effect of using RAg by its optimum dosage in a blend of PG 58-28 binder containing 30% RAPsb on its adhesion with granite and quartzite aggregates and moisture-induced damage was characterized. As a result, a Superpave grade of PG 58-34 was found to be achievable by incorporating 4% RAg in a blend of PG 58-28 and 30% RAPsb. Also, incorporating 4% RAg in a blend of PG 58-28 and 30% RAPsb improved the fatigue resistance of the RAPsb-laden binder to an extent which exceeded that of the neat PG 58-28. Furthermore, an elastic recovery response significantly higher than and a non-recoverable creep response equivalent to those observed in neat PG 58-28 were achieved by incorporating 4% RAg in a blend of PG 58-28 and 30% RAPsb, both having an MSCR grade of PG 58S. Finally, an overall improvement in resistance to moisture damage in PG 58-28 binder containing 30% RAPsb with granite and quartzite was observed as a result of incorporating 4% RAg in the blend.
3 citations
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01 Apr 2011
TL;DR: The use of reclaimed asphalt pavement (RAP) is a useful alternative to virgin materials because it reduces the need to use virgin aggregate, which is a scarce commodity in some areas of the United States as mentioned in this paper.
Abstract: FOREWORD Recycling asphalt pavement creates a cycle of reusing materials that optimizes the use of natural resources. Reclaimed asphalt pavement (RAP) is a useful alternative to virgin materials because it reduces the need to use virgin aggregate, which is a scarce commodity in some areas of the United States. It also reduces the amount of costly new asphalt binder required in the production of asphalt paving mixtures. This report informs practitioners about the state of the practice for RAP use in the United States as well as best practices for increasing the use of RAP in asphalt pavement mixtures while maintaining high-quality pavement infrastructures. High percentage RAP mixtures are achieved with processing and production practices, resulting in cost and energy savings. Based on an evaluation of pavements containing 30 percent RAP through the Long-Term Pavement Performance (LTPP) program, it has been determined that the performance of pavements containing up to 30 percent RAP is similar to that of pavements constructed from virgin materials with no RAP. This report is of interest to engineers, contractors, and others involved in the specification and design of asphalt mixtures for flexible pavements, as well as those involved in promoting the optimal use of RAP. The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report because they are considered essential to the objective of the document. Quality Assurance Statement The Federal Highway Administration (FHWA) provides high-quality information to serve the Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement. Abstract With increased demand and limited aggregate and binder supply, hot mix asphalt (HMA) producers discovered that reclaimed asphalt pavement (RAP) is a valuable component in HMA. As a result, there has been renewed interest in increasing the amount of RAP used in HMA. While a number of factors drive the use of RAP in asphalt pavements, the two primary factors are economic savings and environmental benefits. RAP is a useful alternative to virgin materials because it reduces the use of virgin aggregate and the amount of virgin asphalt binder required in the production of HMA. Using RAP greatly reduces the amount of construction debris going into landfills, and it does not …
332 citations
"Investigation of the oxidation agei..." refers background in this paper
...…low, and the Chinese Department of Transportation is reluctant to use RAP material in expressways because of the decreased cracking resistance of the mixture caused by the aged RAP binder (Copeland 2011, Al-Qadi et al. 2012, Zaumanis and Mallick 2015, Li et al. 2017, 2018a, Yu et al. 2017)....
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01 Jan 2011
TL;DR: In this article, a laboratory study was conducted to evaluate if there was any potential relationship between asphalt binder properties and non-load related cracking, as part of a research project involving airfield asphalt pavements.
Abstract: A laboratory study was conducted to evaluate if there was any potential relationship between asphalt binder properties and non-load related cracking, as part of a research project involving airfield asphalt pavements. The objective of the research was to identify one or more parameters that could be easily determined by testing that would allow an airport manager to monitor the loss of durability experienced with aging and to use the information to evaluate when the airfield asphalt pavement would need preventative maintenance to minimize the effects of non-load associated cracking. Three asphalt binders were selected representing different expected aging characteristics, in the laboratory study. Testing was conducted on asphalt binders in their unaged condition, as well as on asphalt binders that had undergone long-term aging in the Pressure Aging Vessel (PAV) at 100C and 2.1 MPa pressure for 20, 40, and 80 hours. The purpose of the longer PAV aging times was not to correlate with any expected service life, but simply to create a more highly-aged sample. Past research suggested some relationship between ductility (conducted at an intermediate temperature) and the durability of an asphalt pavement. Using ductility as the hypothesized property related to flexibility, two parameters were identified that related well to ductility and the expected loss of flexibility with aging. The first is a parameter suggested by other researchers—G′/(η′/G′)—as determined using the Dynamic Shear Rheometer (DSR). The second is a parameter that quantifies the difference in continuous grade temperature for stiffness and relaxation properties—referred to in the paper as ΔTc. In both cases, the parameters appear to quantify the loss of relaxation properties as an asphalt binder ages. Limited field testing from three general aviation airports generally confirmed the findings from the lab study, with the newer pavements having values of G′/(η′/G′) and ΔTc that displayed more flexibility and less aging than the older pavements. Based on the study results, values were determined for both parameters that could provide an indication of a loss of durability that could result in a greater risk of non-load associated cracking.
268 citations
TL;DR: In this paper, the state-of-the-art approaches for increasing the amount of reclaimed asphalt pavement (RAP) in asphalt mixtures above 40% are summarized and methods to optimise the mix design as well as production technology in order to allow manufacturing of such sustainable mixtures are described.
Abstract: Asphalt is the most recycled material in the USA at a re-use rate of 99%. However, by average only 10–20% reclaimed asphalt pavement (RAP) is used in a given mix design and large part of the RAP is degraded for use in lower value applications. The amount of RAP in asphalt mixtures can be significantly increased with the application of good RAP management practice, readily available modern production technologies and advanced knowledge of mix design. This paper summarises the state-of-the-art approaches for increasing the amount of RAP in asphalt mixtures above 40%. The production challenges and common pavement distresses of very high RAP content mixtures are identified and methods to optimise the mix design as well as production technology in order to allow manufacturing of such sustainable mixtures are described. The best practices for RAP management and economic benefits of high RAP use are also discussed.
249 citations
TL;DR: The main focus of as mentioned in this paper was to obtain plant produced Reclaimed Asphalt Pavement (RAP) mixtures, to document the mixture production parameters and to evaluate the degree of blending between the virgin and RAP binders.
Abstract: The main focus of this study was to obtain plant produced Reclaimed Asphalt Pavement (RAP) mixtures, to document the mixture production parameters and to evaluate the degree of blending between the virgin and RAP binders. The effect of mixture production parameters on the performance (in terms of stiffness, cracking, rutting, and moisture susceptibility) and workability of the mixtures was evaluated. Eighteen plant produced mixtures were obtained from three locations in the Northeast United States. RAP contents (zero to 40%) were varied and softer binders were used. The data and analysis illustrated that the degree of blending between RAP and virgin binders is a function of production parameters. The stiffness of the mixtures increased as the percentage of RAP increased, but not when the discharge temperatures of the mixtures were inconsistent. The cracking resistance was reduced as the percentage of RAP increased. The rutting and moisture damage resistance improved as the percentage of RAP in the mixture...
246 citations
TL;DR: In this paper, a fracture energy and flexibility index (FI) was proposed to screen asphalt concrete mixtures' cracking resistance using the semi-circular bending test geometry, and the results indicated positive correlation between SCB test results and other independent fatigue tests.
196 citations
"Investigation of the oxidation agei..." refers methods in this paper
...The I-FIT test results were analysed using the FI approach recommended by the Illinois Center for Transportation Research (Ozer et al. 2016a, 2016b)....
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