Currently, many countries are facing a dangerous challenge due to shortage in the virgin materials used in highway construction. This problem increases with time as a result of constructing new roads as well as maintaining the existing road network. In addition, construction costs, and oil and fuel prices escalates tremendously in the last few decades. Thus, reusing old pavement materials (reclaimed asphalt pavement, RAP) in new construction gains the attention of researchers and practitioners. Although pavement recycling is widely practiced in the advanced countries, it is still relatively new in the developed countries. One of the major advantages of using the recycled asphalt pavement is that it decreases both the quantity of aggregate and the quantity of asphalt required.
The main purpose of this research was to investigate the influence of using reclaimed asphalt pavement (RAP) materials on the performance of asphalt concrete mixtures containing RAP. Another objective of this study was to determine the maximum RAP
Hissan Al-Kandari percentage that can be added to a new Hot-mix asphalt (HMA) mixture without a significant effect on the mixture performance. A total of five asphalt mixtures containing different percentages of RAP from old pavements in Kuwait were investigated. Marshall tests were conducted on these mixtures to determine the optimum asphalt content according to Kuwait specifications. Asphalt concrete specimens were then prepared at the optimum asphalt content resulted from Marshall tests to investigate the influence of the percentage of RAP in the mixtures on the cracking and rutting resistance through the indirect tensile test and the wheel tracking test. Results showed that, using up to 25% RAP yields about 3.6% reduction in the optimum asphalt content as well as saving in the virgin aggregate without a significant influence on the mixture performance. Furthermore, using more than 25% RAP in the asphalt concrete mixture yields a significant reduction in the mixture performance (resistance to rutting, cracking, stability and flow).