Comparison of Fundamental and Simulative Test Methods for Evaluating Permanent Deformation of Hot-Mix Asphalt

Rutting has long been a problem in hot-mix asphalt (HMA) pavement. Through the years, researchers have used different kinds of fundamental and simulative test methods to estimate the rutting performance of HMA. It has been recognized that most fundamental tests are very complex and simulative tests are generally easy to perform. A comparative study of two fundamental tests [repeated shear at constant height (RSCH) and repeated load confined creep (RLCC) tests] and one simulative test [asphalt pavement analyzer (APA) rut test] is documented. A comparison and correlation of various parameters (permanent deformation or strain, slopes, and intercepts from linear or power law regressions) from these three test results were conducted. The analysis data indicated that the two fundamental tests had significant correlation with APA rut tests. The relationship between the deformation rates and the correlation between initial deformation from the RSCH and RLCC indicate similar deformation behavior of HMAs under RSCH and APA loading conditions. Based on the observed relationships and the existing guidelines for interpreting RSCH permanent shear strain and RLCC permanent strain, preliminary guidelines were recommended for evaluating rut resistance on the basis of APA rut depth. Compared with the existing APA criteria developed by the Georgia Department of Transportation, the acceptable rut depth criteria generated from this study are reasonable and applicable.