Increased environmental regulations and the rising costs of asphalt binder have encouraged researchers to investigate alternative binders that can be used for hot mix asphalt (HMA). This study focused on using bioasphalt as a possible alternative binder to petroleum-based asphalt. To evaluate bioasphalt as a HMA binder, both binder and mixture tests were performed. Bioasphalt was blended with traditional binders at different percentages (0, 10, 30, and 60%) by weight of the base binder. Binder test results, based on constant shear loading tests and multiple stress creep and recovery tests, showed that the addition of bioasphalt decreased the resistance to fatigue and rutting. The HMA mixture performance tests indicated that the addition of bioasphalt to the mix reduced the stiffness of the mix (dynamic modulus) and its resistance to rutting and fatigue cracking, but increased the resistance to thermal cracking. The moisture susceptibility test shows that bioasphalt mixes passed the minimum tensile...

Warm mix asphalt (WMA) is a relatively new and emerging technology for the asphalt industry. It offers potential construction and environmental advantages over traditional hot mix asphalt (HMA). However, WMA must perform at least as well as HMA before it can be used extensively. This study evaluates the performance of WMA mixtures and their corresponding HMA control mixtures obtained from various field sites in the state of Washington. Four WMA technologies are examined, including Sasobit^® and three water-foaming technologies, Gencor^®, Aquablack™ and ALmix Water Injection. Performance tests are conducted on the field cores to evaluate and compare the rutting, moisture susceptibility, fatigue and thermal resistance of WMA and HMA, respectively. Also, the extracted binders from the field cores are evaluated. In addition, the early-age field performance of WMA and HMA control pavements are compared.

Studded tire wear can lead to the severe deterioration of asphalt pavement; therefore, the reduction of studded tire wear is urgently needed to improve asphalt pavement conditions and save repair costs. Steel slag is a coproduct of the steel industry and features high hardness compared to conventional crushed aggregate, such as granite and limestone. This study evaluated the performance of hot-mix asphalt (HMA) that contains steel slag aggregate (SSA) as a surface material to mitigate studded tire wear. The physical properties of the SSA were assessed to determine its suitability in HMA. Four percentages (0, 20, 40, and 60%) of SSA were used in asphalt mixes, and the mix designs for the HMA were conducted in accordance with Superpave mix design. The performance of the mixes was evaluated comprehensively in terms of studded tire wear resistance, thermal cracking resistance, moisture susceptibility, and rutting. The results indicate that the addition of steel slag increased the mixtures’ studded tir...

Bottom-up fatigue cracking, which is a major distress in asphalt pavements, is due to repeated traffic loading that induces tensile stress in the asphalt concrete layers. Fatigue cracks are observed as interconnected cracks in the wheelpath of asphalt pavements. Fatigue cracking can and should be addressed during both the mix design and pavement design. Therefore, a performance indicator is needed during the mix design to select a fatigue-resistant mix. In addition, a fatigue model, which includes the performance indicator, is needed to design the pavement structure. This study is conducted to determine a performance indicator for fatigue and to develop a new fatigue model, based on the Federal Highway Administration's Accelerated Load Facility experiments on fatigue. It is found that the fracture work density (FWD) obtained from indirect tensile testing correlates highly with field fatigue performance, whereas fracture energy fails to correlate with field fatigue performance. A new fatigue model based on FWD is developed herein and is found to be effective in characterising field fatigue performance. Further study is needed to validate the effectiveness of FWD and the new fatigue model.