Asphaltenes-Modified Binders for High Modulus Asphalt Concrete Applications

• Author / Creator

  Ghasemirad, Amirhossein

• Asphalt pavements are the most common type of pavements in North America. Increasing traffic demand, harsh weather conditions, and the tendency for infrastructure operators to reduce the cost (and, therefore, the frequency) of maintenance are the major reasons for asphalt performance improvement strategies.
  High modulus asphalt concrete (HMAC) is an asphalt mixture of high quality designed to have a high strength, good fatigue life, and excellent rutting resistance. However, despite its superior performance, the application of HMAC is limited in cold climates due to its low flexibility and stress relaxation capacity. HMAC gains its superior mechanical performances from its key elements, which are a hard grade binder in conjunction with a strong continuous mineral skeleton. Polymer modified binders are asphalt binders commonly used in HMAC applications, however, the high cost of polymer modified binders as well as the high tendency of phase separation in these binders are the main concerns limiting their applications. On the other hand, sustainability and reduction in cost are the two main factors, which recently lead to incorporation of waste materials into modification of asphalt binders. Asphaltenes are considered as a waste of minimal value with minimal applications in the industry, with a relatively high rate of production in refineries, with the potential to be used in asphalt binder modification applications.
  The current study mainly investigates the application of asphalt binders from different sources modified with asphaltenes for application as high modulus base courses in cold climates. Furthermore, different hard grade asphalt binders, with potential to be used in HMAC applications, are also studied and compared. Furthermore, in order to achieve a deeper understanding of Alberta oilsands asphalt binders, effects of distillation temperature and source of these binders are investigated on their performance at different temperatures. For this purpose, one crude oil binder and four asphalt binders from different Alberta oilsands bitumen sources were studied. Witczak regression model was used to determine the minimum performance grade to meet the dynamic modulus requirement for HMAC. Asphaltenes were used at different percentages for modification of different asphalt binders. A rolling thin film oven (RTFO), and a pressure aging vessel (PAV) were used to simulate different phases of aging which occurs during asphalt pavement service life. Rheological properties of asphalt binders at high and intermediate temperatures were studied using a dynamic shear rheometer (DSR), while at low temperatures a bending beam rheometer (BBR) was used. The effect of asphaltenes modification on the viscosity of the binders was studied using a rotational viscometer. Also, the chemical composition of the asphaltenes-modified binders was determined by SARA analysis. Comparing common hard grade binders with asphaltenes-modified ones revealed that at in regions with cold climates, asphaltenes-modified binder would perform better. Results from rheological analysis indicated that the improving effects of asphaltenes on the performance of binders at high temperatures were relatively higher than its impact at low temperatures. Additionally, it was determined that binders from Alberta oilsands modified with asphaltenes could achieve the performance grade requirements for HMAC applications. Furthermore, from Alberta oilsands binders investigations, it was found that in spite of crude oil asphalts that require modification to achieve performance grade requirements for high modulus asphalt applications, using the right distillation temperature and source, oilsands bitumens were capable of achieving the binder requirements for HMAC applications without further modification.

• Subjects / Keywords

  • Asphaltenes
  • Pavement
  • Modified Asphalt Binder
  • High Modulus Asphalt Concrete
  • Asphalt
  • Base Course
  • Asphalt Binder

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-s53k-er94

• License

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