Fatigue performance of interface bonding between asphalt pavement layers using four-point shear test set-up

This paper aims to study the fatigue performance of interface bonding between asphalt pavement layers. To fulfill this objective, a four-point shear test (4PST) set-up was developed, and a series of fatigue tests were conducted on composite asphalt beam samples made up of stone mastic asphalt (SMA) and asphalt concrete (AC) mixtures. The combined effect of test temperature (3 levels), normal pressure (6 levels), loading frequency (5 levels), and shear stress (6 levels) with single tack coat type and application rate were considered for evaluation. Two interface failure criteria were successfully adopted in this study, and high correlation was relatively found between the fatigue test results and the corresponding fatigue life criteria. Findings of this study revealed that firstly, both the interface fatigue life and shear stiffness increased at all temperatures with increasing normal stress. Secondly, with increasing loading frequency, the interface fatigue life increased at each temperature. Thirdly, shear stiffness decreased with increasing shear stress for each temperature; the decrease was more pronounced at lower temperatures. Power laws were also proposed to characterize interface fatigue life at each temperature. Finally, the results of the analysis of variance (ANOVA) indicated that unlike the fatigue life, all factors had a significant effect on the shear stiffness. A multiple regression model was established successfully to predict the initial shear stiffness.