Evaluation of Mechanical Properties of Asphalt Emulsion Base Course Using Reclaimed  Asphalt Pavement (RAP) and Asphaltenes
Creators: Jhora, Nusrat
Publisher: name: University of Alberta Library
Year: 2023

<p>Road infrastructure significantly impacts the environment, and sustainability practices aim to<br>
minimize this impact. This includes reducing air and water pollution, preserving wildlife habitats,<br>
and reducing the consumption of natural resources. The goal is to minimize the impact of road<br>
development on the environment and natural resources while ensuring that the roads are safe,<br>
efficient, and meet the needs of communities. That is why there has been a growing trend toward<br>
using recycled materials in road construction in recent years. This is primarily driven by a desire<br>
to reduce road construction&#39;s environmental impact and conserve natural resources. Reclaimed<br>
asphalt pavement (RAP), made from recycled asphalt, can be used instead of traditional asphalt in<br>
road construction. RAP is created by milling or grinding up existing asphalt pavement that has<br>
been removed from roads, parking lots, or airport runways and is composed of asphalt binder and<br>
aggregate. Using RAP in pavement construction as a base course material helps to reduce the need<br>
for virgin aggregates and conserve natural resources. The use of RAP also offers several benefits,<br>
including reducing waste and reducing the environmental impact of road construction. But the<br>
quality of RAP can vary depending on its source and the process used to produce it for new<br>
pavement, making it essential to ensure proper quality control measures are in place.<br>
The base layer of a road is one of the layers of the road structure and plays a crucial role in the<br>
overall performance and longevity of the road. Asphalt emulsions are used in road construction<br>
and maintenance to provide a more effective, efficient, and sustainable alternative to traditional<br>
asphalt binders with the possibility of enhancing the properties of the base layer. Therefore, asphalt<br>
emulsions are workable at low temperatures, making them a good option for road construction in<br>
cold climates; they can be used in reconstruction and rehabilitation techniques such as cold in place<br>
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<br>
value and useful application in the pavement industry. Asphaltenes is the most polar component<br>
since it has a higher molecular weight than the other components and adding asphaltenes to an<br>
asphalt mixture makes it stiffer.<br>
The objective of this research is to evaluate and compare the performance properties of the<br>
stabilized base course materials with different contents of RAP (50% RAP, 75% RAP and 100%<br>
RAP), asphalt emulsion with Asphaltenes. The impact of asphaltenes on the tensile strength and<br>
creep compliance performance of the recycled mixtures were investigated at the temperatures of -<br>
20, -10, and 0oC and compared to the control mixture with no asphaltenes content.<br>
A mix design was performed to determine the optimum emulsion content (OEC), considering the<br>
optimum moisture content (OMC) needed for the compaction with the maximum density of the<br>
samples. For mixture modification, a different proportion of Asphaltenes (0.5% and 1%) was<br>
added to the mixture to determine physical and mechanical properties. To determine the permanent<br>
deformation, tensile strength, and low-temperature properties and cracking tolerance of the<br>
modified mixtures, indirect tensile strength (ITS), and creep compliance, strength tests, Hamburg<br>
wheel tracking test (HWT) and the indirect tensile asphalt cracking test (IDEAL CT) were<br>
performed on modified and unmodified mixtures.<br>
Results from the study indicate that modification of the mixtures with asphaltenes improved the<br>
performance of mixtures significantly compared to the control samples for mixtures with 50%<br>
RAP ,75% RAP and 100% RAP.The creep compliance analysis showed that modification of the<br>
mixture material with asphaltenes resulted in lower creep compliance values at below zero<br>
temperatures which consequently improves creep resistance in the modified mixtures for 50%<br>
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<br>
resistant to cracking. However, only for the sample with 50% and 75% RAP, the IDEAL CT-Index<br>
analysis shows that adding asphaltenes will increase the potential for crack propagation of<br>
asphaltenes-modified mixtures regardless of the RAP content. According to the Hamburg wheel<br>
tracking test and RRI results, Asphaltenes modified mixture showed a significant improvement in<br>
the rutting resistance compared to the unmodified mixtures.</p>