The use of warm mix asphalt (WMA) partially mixed with recycled asphalt pavement (RAP) as a base course or a sub-base course is continually gaining interest all over the world, particularly in Europe and North America. The progressive interest and preference of WMA-RAP over hot mixed asphalt (HMA) resides in the exceptional benefits WMA-RAP offers. Those benefits include health benefit to workers, economic benefits, and paving benefits in cold weather condition. Although WMA partially mixed with RAP was originally created to overcome the environmental challenges and the shortages of natural resources, the fact remains that it has shortcomings in performing well against rutting failure, and moisture damage. Therefore, this paper aims to evaluate and to understand the mechanical performances of WMA partially mixed with RAP in terms of fatigue cracking and rutting damage. In order to achieve the aim of this study, the indirect tensile strength test was conducted. Thereafter, the results obtained were used as input data to model the flexible pavement. Furthermore, various scenarios of structural flexible pavements subjected to the effect of load were analysed and modeled using the 3D finite element method (FEM) in ABAQUS and the layered elastic analysis (LEA) as a control. The Results showed that the HMA and the WMA were in close proximity, as the percentage difference between the horizontal strain at the bottom of the asphalt layers 3.7% for the 3D FEM Model and the compressive vertical strain on the top of the sub-grade 1%, which imply that the WMA can perform more or less as the HMA. Overall, the RAP can be incorporated successfully in the WMA which can be applied to new construction and rehabilitation of low to medium traffic volume roads.