Investigating the Effect of Using Waste Ultra-high-molecular-weight Polyethylene on the Fatigue Life of Asphalt Mixture

One of the effective parameters in the occurrence of fatigue cracking distress is the asphalt binder properties used, which must be controlled by appropriate asphalt binder or additives. In this study, the effect of using Ultra-High-Molecular-Weight Polyethylene (UHMWPE) was investigated on the fatigue cracking potential of asphalt mixtures. Two types of aggregates, asphalt binder performance grade (PG) 64-16, and UHMWPE additive in two percent of the asphalt binder were used in this study, which were tested at two temperatures and five different stress levels. Marshall mix design and indirect tensile fatigue test (ITFT) were used to determine the optimum content of the asphalt binder and the fatigue life of asphalt mixtures, respectively. The results of this study indicated that the application of polymer additives increased the fatigue life of the asphalt mixtures. The fatigue life of specimens made with granite aggregates was longer than those made with limestone aggregates, and the increased life due to the use of UHMWPE was longer in samples made with granite aggregates. As expected, increasing in temperature and stress levels reduced the fatigue life of the asphalt mixtures. This decrease was much lower in samples made of asphalt binder modified with polymeric materials than in control samples

Effect of Nano-Cobalt Oxide on the Rheological Behavior of Asphalt Binder and Mechanical Characteristics of Hot Mix Asphalt

In this study, the effects of nano-cobalt oxide (nano-CoO) (1 and 2% by asphalt binder weight) on the rheological behavior of the asphalt binder and mechanical characteristics of asphalt mixtures were examined. To evaluate the behavior of the asphalt binder at moderate and high temperatures, the dynamic shear rheometer (DSR) test was used. Besides, to study asphalt mixtures’ rutting potential and fatigue cracking, the repeated load axial (RLA) test and the indirect tensile fatigue test (ITFT) were conducted, respectively. Based on the rheological tests, adding 1 and 2% of nano-CoO to asphalt binder increases the complex modulus (G∗) and reduces the phase angle (δ) at high temperatures and significantly improves the modified asphalt binder’s rutting parameter. Also, at moderate temperatures, the addition of nano-CoO reduced the fatigue parameter of the modified asphalt binder compared to the control asphalt binder. It was demonstrated that the permanent strain of the modified specimens was decreased by about 35% compared to that of the control specimens. The fatigue tests at two temperatures and five stress levels also showed that incorporating nano-CoO significantly increased (about 90%) the fatigue life of modified samples compared to controlled samples