This research aimed to study on the characteristics of base course materials and to determine reliable mathematical material models for the improvement in the current pavement design criteria. In this study, there were two relevant factors of both pavement materials which are considered in order to fulfil a lack of understanding in realistic conditions in pavements of the current pavement design. 1) The material strength which indicates the limitation and stability of pavement materials under traffic loads. This study defined the limitation of material implementation and also brought in the resilient modulus of materials to be the significant input parameter for multi-layer finite element analysis. 2) The pavement failure of long term road performance relating to the design life of pavements. The permanent deformation behaviour and the shakedown concept under various stress conditions, simulated from repeated load triaxial (RLT) tests, therefore, were taken into account to investigate such long-term performance. Furthermore, more reliable mathematic models of base course materials during their service life were established.