FATIGUE CRACK CHARACTERISTICS OF HMA MIXTURES CONTAINING RAP B. Huang, Z. Zhang, W. Kingery and Gang Zuo The University of Tennessee, USA Abstract This paper presents the preliminary findings of a laboratory study, in which the fatigue characteristics of hot-mix asphalt mixtures containing reclaimed asphalt pavement (RAP) were evaluated. A typical surface mixture commonly used in the state of Tennessee was evaluated at 0, 10, 20, and 30 percent of 4.75-mm sieve screened RAP content. Mixtures were subjected to long-term aging after being compacted. Fatigue characteristics of mixtures were evaluated through indirect tensile strength, semi- circular bending (SCB) and semi-circular notched fracture resistance tests. Preliminary test results indicated that the inclusion of RAP generally increased the tensile strength and improved the mixture’s resistance to fracture failure for the mixtures in this study. However, mixture’s properties changed significantly when the RAP content increased to 30 percent. 1. Introduction Reclaimed asphalt pavement (RAP) has been used in pavement construction since 1930s [1]. It was not, however, until the mid to late 1970s, that the use of RAP became popular in the asphalt pavements [2]. In spite of wide application of RAP materials today, the use of RAP in major load carrying and surface layers of asphalt pavements has always been a sensitive issue. Generally, the addition of RAP in the HMA mixtures will blend the long-term aged asphalt cement in the RAP with the fresh asphalt binder. The resulting asphalt cement in the mixtures tends to be stiffer. The main concerns to such mixtures are their resistance to long-term fatigue cracking. For this reason, most state departments of transportation (DOT) in the US either limit or restrict the use of RAP on the surface layer and limit the percentage use of RAP on the structural layers. 2. Objective The objective of this paper was to analyze the fatigue characteristics of hot-mix asphalt mixtures containing RAP through laboratory performance tests. A typical surface mixture commonly used in Tennessee was evaluated at 0, 10, 20, and 30 percent of