Evaluation of the significance of different mix design variables on asphalt mixtures’ cracking performance measured by laboratory performance tests

Abstract

Cracking is one of the primary distresses for asphalt pavements. This study is motivated to investigate the significance of the various mix design variables in determining the cracking performance of asphalt mixtures including both intermediate and thermal cracking performance, contributing to a better understanding of the mix design to improve the mixture cracking performance and promoting the development and implementation of the performance related specification and performance based specification. Total 20 mixtures were tested and evaluated in this study. The most current state of the practice mixture performance tests, including the Complex Modulus (E*) test, Semi Circular Bending (SCB) test, Disk Shaped Compact Tension (DCT) test and Direct Tension Cyclic Fatigue (DTCF) test were conducted on these mixtures for characterization of their cracking performance. The advanced statistical analysis methods were employed on the generated data base to investigate the significance of the mix design variables on determining the cracking performance parameters measured from the laboratory tests. The correlations between the various cracking performance parameters measured from the tests were also evaluated in this study. The results show that the binder related mix variables play the significant role for determining both the low temperature and durability cracking performance of asphalt mixture. For evaluation of the mixture fatigue cracking performance, several aggregate related variables in addition to binder variables are identified as the significant factors. Correlation analysis shows that mixture rheological based cracking parameter G-Rm does not show the strong correlations with neither the facture indices measured from the DCT and SCB tests nor the fatigue parameters measured from the DTCF test. This study also develops a simplified linear regression model as a predesign tool for evaluation and prediction of mixture cracking performance in general.