Experimental investigation of tack coat fatigue performance: Towards an improved lifetime assessment of pavement structure interfaces

This paper focuses on investigating the bonding fatigue performance between two asphalt concrete (AC) layers. For purposes of this experimental campaign, a customised double shear testing device was designed. Two interface conditions have been analysed herein: with and without a tack coat. Moreover, the corresponding fatigue behaviour has been analysed at two temperatures: 10 °C and 20 °C. As expected, the absence of a tack coat leads to a decrease in bonding fatigue performance. Since fatigue tests are highly time-consuming, a method that allows predicting the conventional interface fatigue law from accelerated shear fatigue tests has been proposed. Other novel findings on interface fatigue behaviour will also be discussed. In addition to these fatigue results, an interface failure model is proposed to evaluate the interface lifetime. Incorporating interface fatigue performance into pavement analysis proves to be a key parameter in describing in situ pavement conditions and assessing pavement durability.