Development of a Permanent Deformation Model of Asphalt Mixtures for South Korean Pavement Design Guide

Abstract

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