The Korean Pavement Design Guide (KPDG) has been developed based on the mechanistic-empirical principle. This paper presents the permanent deformation model of asphalt mixtures in the KPDG. The permanent deformation modelhas been developed for various types of asphalt mixtures using the triaxial repeated loading test. This model has been calibrated with Accelerated Pavement Test (APT) and Long Term Pavement Performance (LTPP) database. Through triaxial repeated loading tests, the permanent deformation model of asphalt mixtures has been developed to address the effect of temperature and initial air voids. The model coefficients for the temperature and air void obtained from the triaxial tests do not need to be calibrated. However, the model coefficients for the shift factor and number of load repetition should be calibrated with APT data. It is found from this study that themodel requires a correction factor to consider the effects of total asphalt concrete (AC) layer thicknesses. The correction factor is useful to simulate the distribution of real vertical plastic strain for different AC layer thicknesses. A shift factor has been found by comparing the measured rut depth from the LTPP sections and predicted values from the KPDG program. It is observed from a verification study that the final permanent deformation model developed in this study can predict the field rut depth of various AC pavements quite accurately.
Abstract