The primary objective of this project is to propose a laboratory setup to test and evaluate an asphalt mixture layer on top of a simulated Cement-Treated Base (CTB) layer against reflective cracking. An in-depth literature review on the experimental studies that were conducted throughout the world to investigate the resistance of asphalt mixtures to reflective cracking was conducted. Texas Transportation Institute (TTI) Overlay Tester (OT) was found to be the most appropriate equipment to study thermally-induced reflective cracking in the laboratory, and thereby was selected to be modified and used to assess the performance of asphalt mixtures on top of a pre-cracked CTB layer. Four different asphalt mixtures and two types of stabilized bases were successfully prepared in this study. The reflective cracking performance of the laboratory-produced asphalt mixtures was evaluated using both the modified and conventional OT setup at two different test temperatures. The attempt to modify the conventional OT setup for better mimicking field reflective cracking was unsuccessful because of the inability to establish a bonding between the top and bottom layers of the composite OT specimens. The repeatability of the collected data was acceptable since COVs were below 30%. Results of the conventional OT testing showed that decreasing the test temperature from room to low temperature resulted in the asphalt mixtures to change their behavior from “soft crack-resistant” mixtures to “tough crack resistant” mixtures. On the other hand, no observable effect of changing binder type and RAP content was found when the specimens were tested in conventional OT setup.
Sadek, H., Hassan, M., Berryman, C., Hossain, M., & Idris, I. (2020). Evaluation of Asphalt Mixtures’ Resistance to Cement-Treated Base (CTB) Reflective Cracking in the Laboratory. Retrieved from https://digitalcommons.lsu.edu/transet_pubs/87