Evaluation of Binder Aging and Its Influence in Aging of Hot Mix Asphalt Concrete: Technical Report (original) (raw)
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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.
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International Journal for Computational Civil and Structural Engineering
The effect of temperature level and its exposure time in hot mix asphalt production stages on the conventional and rheological properties of asphalt cements have been investigated through experimental study. A series of Rolling Thin Film Oven (RTFO) Test was conducted at the temperature/time combinations for 135, 150, 163 ºC and 40, 80, 120 minutes. Dynamic mechanical characteristics of the binders were detected by dynamic shear rheometer tests. The results show that the variations in exposure time and temperature distinctly changed the properties of binders in a wide range. It is recommended that for a better simulation of short term aging in production and construction stages, RTFO test temperature and curing time should be adjusted according to the real individual field conditions. Also, in order to give information about the aging behavior of a specific binder for possible field conditions, the test results should be presented for a number of temperature-time combinations.
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.
Aging of Rejuvenated Asphalt Binders
Advances in Materials Science and Engineering, 2017
An important concern that limits the RAP content in asphalt mixtures is the fact that the aged binder that is present in the RAP can cause premature cracking. Rejuvenators are frequently added to high RAP mixtures to enhance the properties of the binder. There is no existing method to predict the longevity of a rejuvenated asphalt. This study investigated the aging of rejuvenated binders and compared their durability with that of virgin asphalt. Various samples with different types and proportions of RAP, virgin binder, and rejuvenator were aged by RTFO and three cycles of PAV. DSR and BBR tests were conducted to examine the high-temperature and low-temperature rheological properties of binders. Results indicated that the type and dosage of the rejuvenator have a great influence on the aging rate and durability of the binder. Some rejuvenators make the binder age slower, while others accelerate aging. These observations confirm the importance of evaluating the long-term aging of rec...
Empirical Model to Account for the Effect of Mineral Fillers on Aging Rates of Asphalt Mixtures
Ph.D. Dissertation - Chapter 8, 2017
Oxidative aging is a major factor that affects asphalt mixture properties throughout a pavement's service life and is recognized as a major distress mechanism in asphalt concrete pavements. Aging increases the stiffness and brittleness of the material, which leads to a high potential for cracking. Thus, an improved understanding of the oxidative aging phenomenon and its effect on asphalt binder rheology will also improve the feasibility and accuracy of the characterization of asphalt mixture properties as a function of pavement service life. Long-term oxidative aging is a complex and slow process that occurs at ambient temperatures and pressures throughout a pavement's service life. In order to simulate this complex phenomenon in the laboratory, an accelerated aging procedure must be implemented in order to match field aging levels within a practical time frame without altering the oxidative reaction mechanism that may occur in the field throughout the service life of the pavement. 5 This chapter is proposed to be submitted for publication as: Empirical Model to Account for the Effect of Mineral Fillers on Aging Rates of Asphalt Mixtures. Construction and Building Materials. I, Michael D. Elwardany, contributed to this paper by comparing binder thin-film aging rates using USAT and loose mix aging rates and developing an empirical model to account for the effect of mineral fillers on oven aging rates of asphalt mixtures. Elwardany, M. D. (2017). Phenomenological modeling and laboratory simulation of long-term aging of asphalt mixtures-PhD dissertation (NCSU)
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).