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Evaluation of Mechanical Properties of Asphalt Emulsion Base Course Using Reclaimed Asphalt Pavement (RAP) and Asphaltenes

  • Author / Creator
    Jhora, Nusrat
  • Road infrastructure significantly impacts the environment, and sustainability practices aim to
    minimize this impact. This includes reducing air and water pollution, preserving wildlife habitats,
    and reducing the consumption of natural resources. The goal is to minimize the impact of road
    development on the environment and natural resources while ensuring that the roads are safe,
    efficient, and meet the needs of communities. That is why there has been a growing trend toward
    using recycled materials in road construction in recent years. This is primarily driven by a desire
    to reduce road construction's environmental impact and conserve natural resources. Reclaimed
    asphalt pavement (RAP), made from recycled asphalt, can be used instead of traditional asphalt in
    road construction. RAP is created by milling or grinding up existing asphalt pavement that has
    been removed from roads, parking lots, or airport runways and is composed of asphalt binder and
    aggregate. Using RAP in pavement construction as a base course material helps to reduce the need
    for virgin aggregates and conserve natural resources. The use of RAP also offers several benefits,
    including reducing waste and reducing the environmental impact of road construction. But the
    quality of RAP can vary depending on its source and the process used to produce it for new
    pavement, making it essential to ensure proper quality control measures are in place.
    The base layer of a road is one of the layers of the road structure and plays a crucial role in the
    overall performance and longevity of the road. Asphalt emulsions are used in road construction
    and maintenance to provide a more effective, efficient, and sustainable alternative to traditional
    asphalt binders with the possibility of enhancing the properties of the base layer. Therefore, asphalt
    emulsions are workable at low temperatures, making them a good option for road construction in
    cold climates; they can be used in reconstruction and rehabilitation techniques such as cold in place
    recycling (CIR). Using cold in-place recycling process, asphalt emulsion stabilized mixture produced with RAP and asphaltenes, is waste material from Alberta oil sand with no significant
    value and useful application in the pavement industry. Asphaltenes is the most polar component
    since it has a higher molecular weight than the other components and adding asphaltenes to an
    asphalt mixture makes it stiffer.
    The objective of this research is to evaluate and compare the performance properties of the
    stabilized base course materials with different contents of RAP (50% RAP, 75% RAP and 100%
    RAP), asphalt emulsion with Asphaltenes. The impact of asphaltenes on the tensile strength and
    creep compliance performance of the recycled mixtures were investigated at the temperatures of -
    20, -10, and 0oC and compared to the control mixture with no asphaltenes content.
    A mix design was performed to determine the optimum emulsion content (OEC), considering the
    optimum moisture content (OMC) needed for the compaction with the maximum density of the
    samples. For mixture modification, a different proportion of Asphaltenes (0.5% and 1%) was
    added to the mixture to determine physical and mechanical properties. To determine the permanent
    deformation, tensile strength, and low-temperature properties and cracking tolerance of the
    modified mixtures, indirect tensile strength (ITS), and creep compliance, strength tests, Hamburg
    wheel tracking test (HWT) and the indirect tensile asphalt cracking test (IDEAL CT) were
    performed on modified and unmodified mixtures.
    Results from the study indicate that modification of the mixtures with asphaltenes improved the
    performance of mixtures significantly compared to the control samples for mixtures with 50%
    RAP ,75% RAP and 100% RAP.The creep compliance analysis showed that modification of the
    mixture material with asphaltenes resulted in lower creep compliance values at below zero
    temperatures which consequently improves creep resistance in the modified mixtures for 50%
    RAP, 75% RAP . On the other hand, asphaltenes-modified samples had higher tensile strength and fracture energy than the control sample at room temperature. It shows that the samples are more
    resistant to cracking. However, only for the sample with 50% and 75% RAP, the IDEAL CT-Index
    analysis shows that adding asphaltenes will increase the potential for crack propagation of
    asphaltenes-modified mixtures regardless of the RAP content. According to the Hamburg wheel
    tracking test and RRI results, Asphaltenes modified mixture showed a significant improvement in
    the rutting resistance compared to the unmodified mixtures.

  • Subjects / Keywords
  • Graduation date
    Fall 2023
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/r3-zb80-6n73
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.