A review of asphalt and asphalt mixture aging (original) (raw)
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A review of asphalt and asphalt mixtures aging
This paper presents an extensive review of the pertinent literature regarding asphalt and asphalt mixture Aging. Aging affects flexible pavement performance and is produced by intrinsic and extrinsic variables as well as exposure time. Intrinsic variables include asphalt and aggregate properties, a mixture's asphalt content, binder film thickness and air void content; extrinsic variables are associated with production (short-term aging) and exposure to environmental field conditions (long-term aging). Taken together, both variables demonstrate that aging results from three distinct mechanisms: volatilisation, oxidation and steric hardening. Temperature, pressure and photo degradation treatments are used to simulate aging in the laboratory and empirical and semi-empirical models are created to represent and study aging. Aging increases asphalt complex modulus and decreases the phase angle. Mixtures become stiffer while fatigue life becomes reduced. Carbonyl and sulfoxide group formation in asphalt are often studied as such chemical changes show oxidation in aged asphalts. The prevailing models used to predict asphalt aging are discussed, though more comprehensive research into asphalt aging is still needed.
Ph.D. Dissertation Chapter 2 - Literature Review, 2017
Asphalt binder consists mainly of organic materials that react chemically with atmospheric pressure in a process known as oxidative aging. Oxidative aging of asphalt binders in pavements has a pragmatic importance as it generally leads to a significant change in its chemical composition and rheological properties. Since oxidative aging has long been recognized to contribute to pavement embrittlement and loss of fracture resistance, therefore oxidative aging has been considered one of the major distress mechanisms for asphalt concrete pavements. The chemical and physicochemical mechanisms of asphalt oxidative age hardening and changes in the rheological properties of asphalt resulting from oxidation of asphalt binder have been the focus of plentiful research efforts for almost a century. A comprehensive and critical literature review on binder aging can be found in (Petersen 2009, Glover et al. 2008). Petersen (1984) shows the reaction mechanisms of oxidation of asphalt binders and the species naturally occurring in asphalt binders like sulfide and carboxylic acid versus the species that are formed due to oxidation presented like Sulfoxide, Anhydride, and Ketone, taking in consideration that although Carboxylic acid can is naturally occurring in asphalt binders its concentration increases with evolution of oxidation reaction (Petersen 2009).
Long-term ageing of asphalt mixtures
Road Materials and Pavement Design, 2017
Ageing of asphalt mixtures occurs during production and construction and continues throughout the service life of the pavement. Although this topic has been studied extensively, recent changes in asphalt mixture components, production parameters, and plant design have raised a need for a comprehensive evaluation that considers the impacts of climate, aggregate type, recycled materials, WMA technology, plant type, and production temperature. In this study, field cores were acquired from seven field projects at construction and several months afterwards, and raw materials were also collected for fabricating laboratory specimens that were long-term oven aged (LTOA) in accordance with selected protocols. The resilient modulus and Hamburg wheel tracking tests were conducted on both specimen types to evaluate the evolution of mixture stiffness and rutting resistance with ageing. The concepts of cumulative degree days and mixture property ratio were proposed to quantify field ageing and its effect on mixture properties. Test results indicated that the LTOA protocols of two weeks at 140°F (60°C) and five days at 185°F (85°C) produced mixtures with equivalent in-service field ageing of 7-12 months and 12-23 months, respectively, depending on climate. Finally, among the factors investigated in the study, WMA technology, recycled materials, and aggregate absorption exhibited a significant effect on the long-term ageing characteristics of asphalt mixtures, while production temperature and plant type had no effect.
Evaluation of Short-Term Aging Protocol for Asphalt Mixtures
Applied Sciences, 2019
Asphalt mixtures are subjected to short-term aging during the production, placement, and compaction processes. Proper evaluation of asphalt pavement performance relies on the accurate characterization of asphalt mixtures during the design stage. In this study, three different loose asphalt mixtures often used in Qatar were evaluated to develop a laboratory short-term aging procedure. Sample mixtures 1 and 3 were collected from a construction site, while mixture 2 was obtained from an asphalt plant. Virgin aggregates and binders were also collected to reproduce the mixtures in the laboratory. Laboratory-produced mixtures were conditioned at 135 °C using various time durations. The mechanical properties of laboratory-produced mixtures were compared to those of mixtures produced on site. The results of the mechanical and binder testing demonstrated that the proper short-term aging protocol for asphalt mixtures often used in road construction in the State of Qatar would involve heating ...
Laboratory investigation of asphalt mixture aging
Proceedings of 6th Eurasphalt & Eurobitume Congress, 2016
The rheological properties of asphalt binders change with time. Asphalt mixtures get stiffer and more prone to fatigue cracking with aging. This study is a part of a comprehensive study undertaken to develop improved protocol for asphalt mixture conditioning in the laboratory to simulate asphalt mixture aging due to the climate conditions in the State of Qatar. In this study, asphalt mixtures were prepared by mixing Gabbro base aggregate with Pen 60-70 binder. Initially, mixtures were conditioned at short-term aging temperature of 135°C for different time periods (2, 4 and 6 hrs). Long-term aging was completed after compaction of test specimens to the desired air void level of 7 ± 0.5% by using Superpave gyratory compactor. Three different long-term aging temperatures (i.e., 75, 85 and 95°C) and four different aging levels (0, 2, 6, and 10 days) were evaluated in this study. Then, the specimens were tested in an AMPT to determine dynamic modulus and phase angle. Results of this study were presented by plotting a series of mastercurves obtained from performance testing of the aged specimens. The results showed that aging temperature and duration have significant effects on the viscoelastic properties of asphalt mixtures.
Effect of Aging on the Properties of Asphalt and Asphalt Mixtures
Ingenieria y Universidad, 2015
This article presents the results of the analysis of the effect of aging on the properties of asphalt and asphalt mixtures. The objective of this study was to compare the properties of the original asphalt and aged asphalt and the dynamic modulus of asphalt mixtures. The long-term aging was simulated by using Pressure Asphalt Vessel (PAV). Marshall and RAMCODES methodologies were used to determine the formula of work; values of dynamic modulus of designed mixtures were obtained by the indirect tensile test, using the Nottingham Asphalt Tester (NAT). The results showed an increase in the rigidity of the aged asphalt. Also, an increase of the stability and a decreased flow in the mixtures made with this type of binder was found. The dynamic modulus values of the mixtures containing aged asphalt showed an increase up to three times compared with those elaborated with original asphalt mixtures.
Investigation of the asphalt mixture morphology influence on its ageing susceptibility
Materials and Structures, 2013
The main objective of this study is to investigate the influence that asphalt mixture morphology aspects have on its overall ageing behavior. Since mixture morphology is controllable, having insight into how the various morphological parameters influence the mixture's long-term behavior can be of great value to optimize its design, regardless of the individual material properties. To do so, this study is utilizing a new framework to characterize the combined effect of aggregate packing, average air void size, porosity and level of compaction on ageing for a large set of data from different sources of field compacted and laboratory produced asphalt mixtures. The paper also hypothesizes about the mechanisms that lay behind the found influences and how thus mixture design improvements can be made. From all the investigated cases, it was found that the framework can be used to optimize the durability performance of asphalt mixtures. It was also observed that prediction of ageing behavior without considering the influence of mixture morphology may lead to erroneous conclusions and non-optimal mix design.
IAEME, 2019
The phenomenon of aging of asphalt binders and asphalt mixtures impacts directly in the physical-mechanical response and durability of asphalt pavements. Because of such reason, multiple research efforts have been carried out in relation to this topic. By conducting a deep bibliographical review, the most important aspects that the pavement engineer needs to be aware of in relation to the aging of asphalt binders and asphalt mixtures were organized and summarized. This information was summarized and described in two articles. This first one (Titled Part I), introduces and describes the changes that physical-chemical properties of asphalt binders and asphalt mixtures undergo when they age. Additionally, commonplace tests for attempting to evaluate said properties in these materials are introduced.
IAEME, 2019
This the second part of an article written with the purpose of summarizing and describing the most important aspects that the pavement engineer should know about the aging of asphalt binders and asphalt mixtures. The first part presented the changes in physical and chemical properties undergone in asphalt binders and asphalt mixtures when they age. This article shows the most widely used methods for simulating the aging of asphalt materials. Additionally, the most popular and currently used techniques for reducing aging effects in mechanical response and durability of asphalt mixtures in service are presented.