Characterizing the fatigue cracking behaviors of OGFC pavements using the overlay tester

The objective of this study was to evaluate the fatigue performance of the composite specimens combined by OGFC and the underlying dense-graded layer (OGFC-AC) by conducting overlay tester (OT) tests. Other two types of specimens, including single layer OGFC13 and single layer AC20, were fabricated to make comparable analysis with OGFC-AC composites. For OGFC-AC specimens, the effects of tack coat application rate and contaminations (soil and oil) were quantificationally explored. Peak tensile stress, cracking rate index (CRI), and dissipated energy were obtained and analyzed. Meanwhile, the damage propagation during the fatigue tests were analyzed using a damage factor. Results indicated that the peak tensile stresses of OGFC-AC composites were somewhere between OGFC13 and AC20. Contaminations would attenuate the peak tensile stress. There existed a power exponential relation between dissipated energy and the load cycle. CRI and damage factor presented the same development law in demonstrating that the fatigue cracking resistance of OGFC13 was superior, followed by AC20, and the performance of OGFC-AC was inferior. The results of CRI and damage factor showed that an optimum tack coat application rate (0.4 kg/m(2)) existed at which the OGFC-AC composites presented the least cracking potential. The contamination of soil partially increased the cracking resistance, which was probably due to the fact that some sand particles in soil increased the friction and interlock effect between OGFC and the AC layer.