Laboratory investigation of interlayer shear fatigue performance between open-graded friction course and underlying layer

The objective of the study was to evaluate the bonding fatigue performance between open-graded friction course (OGFC) and underlying layer through laboratory testing at different tack coat application rates. Direct shear fatigue test was performed to obtain the shear fatigue properties of the composite specimens composed of OGFC and its underlying layer. Two types of dense graded asphalt mixture (named BM and TLD in Tennessee) were selected as the underlying layer. In addition to the fatigue life determined according to the conventional 50% stiffness reduction method, energy approach was also employed to analyze the fatigue behavior of the composite specimens. Results showed that the OGFC-TLD structure gave a better shear fatigue performance than OGFC-BM. With the increase in tack coat application rate, the plateau value (PV) increased and the total cumulative dissipated energy decreased for both combined structures. The contact area between OGFC and the underlying layer was measured and correlated to the fatigue life. The contact area between OGFC and TLD was larger than that between OGFC and BM, leading to a better fatigue performance of OGFC-TLD.