Performance Evaluation of Stabilized Base Courses Comprising TSRU Tailings and Bitumen Froth Derived from Alberta Oil Sands
Creators: Sheonty, Sabrina Rashid
Publisher: name: University of Alberta Library
Year: 2022

<p>Sustainable pavement infrastructure is an essential component for the economic development for any country. The quality of materials of pavement layers impacts the long-term performance of pavement structures. Low quality granular materials can result in pavement deformation and reduced pavement life. But due to the unavailability or high cost, it is not always possible to provide good quality granular materials in the flexible pavements. In this context, stabilization have become popular in recent times to enhance the unbound layer properties. However, the commonly used stabilizing agents have some economic constraints and environmental concerns. Hence, researchers are continually seeking alternative and creative materials. <br>
Tailing solvent recovery unit (TSRU) tailings obtained from oil sands bitumen are waste materials with no significant use in current practice. On the other hand, bitumen froth is another by-product produced in oil sand industries. The TSRU tailings stream mainly contains water, asphaltenes, fines, solids, bitumen and residual solvent. Typically, the recovered bitumen froth contains water and solids in it. In terms of economic prospect and composition, TSRU tailings and bitumen froth can be good stabilizing agents. There has been no publicly available study so far about the application of TSRU tailings and bitumen froth in pavement construction. Hence, this study aims to bridge this research gap. <br>
The objective of this research is to investigate the application of TSRU tailings and bitumen froth in pavement construction, and reduce the thickness of granular layer of pavement by improving the layer property with these modifiers. At the initial stage of it, the characteristics of TSRU tailings, bitumen froth and granular materials were evaluated using a number of laboratory testing methods. For mixture preparation, different bitumen froth contents were added to the mixture, and different properties of the mixes were determined. To investigate the tensile strength and moisture sensitivity properties of the modified mixtures, indirect tensile strength (ITS) test was performed on modified mixtures. To estimate the change in thickness before and after TSRU modification, California bearing ratio (CBR) and Marshall stability tests were performed, and the layer thickness change was estimated according to AASHTO 1993. To improve the moisture sensitivity property of the modified samples, cement was added as an additive, then ITS test was conducted, and tensile strength ratios (TSR) were calculated for the cement-treated samples. Additionally, in order to understand the cracking resistance of cement-modified mixtures, cracking tolerance (CT) of the samples was determined using the indirect tensile asphalt cracking test (IDEAL-CT). <br>
Results from the study indicated that TSRU tailings and bitumen froth modification could improve the tensile strength of mixtures, and reduce the thickness of the granular layers significantly. On the other hand, the moisture sensitivity of the TSRU-modified sample was found high. Cement treatment can improve the moisture resistance of the TSRU-modified samples but at the same time, it increases the cracking potential of the modified mixes.</p>