The maintenance and rehabilitation of highway network systems are major road agency expenditures. The combined effects of environmental conditions, traffic loading, moisture, construction quality, and maintenance contribute significantly to rates of pavement deterioration and the length of asphalt pavement life. One of the important performance parameters for asphalt concrete pavements, particularly in cold regions, is the capability to withstand cyclic temperature changes. Such temperature cycles, especially those that alternate above and below freezing, lead to mechanical stresses that can cause failure. This research presents the results and major findings of an experimental investigation performed on rectangular asphalt slab samples extracted from newly constructed pavements of actual highway projects, rather than gyratory-compacted samples that are created in the laboratory. The first phase (Test Series A) studied the effects of temperature cycles and compaction equipment on interlayer bonds by using a custom-made temperature cycling testing machine that allows the reproduction of several temperature cycles over a relatively short time (7-10 days). The second phase (Test Series B) focused on resistance to tensile stresses under cold temperatures. During Test Series B, a custom-made direct tensile strength test was employed to estimate the tensile strength of slab samples at different temperatures (i.e., 0°C, -10°C, or -20°C) for single-and double-layer samples. Test Series B included 171 asphalt samples 300mm long by 100mm wide, with thicknesses of 50mm for single layers and 100mm for double layers. I would like to express my great appreciation to Professor A. O. Abd El Halim for kindly accepting me as his PhD student. His guidance, support and valuable input were treasured throughout my studies at Carleton University. I am very sad that he passed away on September 19, 2019, and that I could not defend my thesis while he was still with us. Special thanks to Professor Yasser Hassan, Chair of the Department of Civil and Environmental Engineering and my current thesis supervisor, for his support, advice, valued comments, and constructive criticisms. I would like to acknowledge Carleton University for their financial support, and RW Tomlinson Limited for providing the asphalt specimens. I also thank Stanley Conley, Jason Arnott, and Stephen Vickers for their participation and assistance in operating the environmental chamber, design and construction of the testing tables and help during the test series; they greatly enabled and supported my work and helped me get results of better quality. The author is grateful to Dr. Bashar Dhahir for his assistance in the modelling and statistical analysis. I would like to acknowledge the experimental works completed jointly with Graziela Girardi, P.Eng at early stages of my studies at Carleton
