Investigation of the fracture performance of reclaimed asphalt mixture at the intermediate temperature using multi-parameters

Abstract

Fracture energy (Gf) and J-integral are two widely used parameters to evaluate the intermediate-temperature fracture performance of hot mix asphalt. Other parameters, such as balanced cracking index (BCI), cracking resistance index (CRI), cracking tolerance index (CTindex) and toughness index (TI), were proposed to characterize the fracture performance subtly. However, these parameters generally could not generate consistent fracture performance. In this study, six indices (Gf, J-integral, BCI, CRI, CTindex and TI) were selected to characterize the intermediate-temperature fracture performance of HMA to address the effects of RAP and rejuvenator on the fracture resistance. The overall fracture performance of all mixtures was evaluated using all these parameters using a scoring method. Pairwise correlation analysis was conducted among the variables. In addition, coefficients of variability (COV) were also measured. The results showed that all facture parameters indicated that a certain amount of RAP could enhance the fracture performance. However, the optimal contents of RAP were inconsistent among different fracture parameters. Rejuvenator could improve the fracture resistance. The fracture score of HMA with 50% RAP was highest, indicating the fracture resistance of HMA with 50% RAP was superior considering all the fracture variables. Pairwise correlation analysis showed that Gf presented poor correlations with all other variables. BCI, CTindex and TI showed large COVs, while Gf, J-integral and CRI showed low COVs.