The price of asphalt binder has increased dramatically due to the increase in oil prices and the increase in traffic volumes occurring worldwide. This situation has prompted calls for greater viscosity, lower‐cost asphalt for pavement construction, and the development of alternative materials that have a good rheological effect, are less expensive, and have a reduced negative impact on human health and the environment. The application of fibers in asphalt mixes has been studied over the past few decades to improve pavement performance around the world. This study was conducted on three types of asphalt binders that were modified with two types of fibers: brown recycled wool fiber (BRWF), available locally in Iraq, and China polyester fiber (CPF), which is considered as waste, to produce fiber‐modified asphalt binders. The samples were conducted using traditional physical testing (penetration, softening point, and rotational viscosity tests) as well as the Dynamic Shear Rheometer (DSR) test. In comparison to the original asphalt binders, the fiber‐enhanced asphalt binders had greater softening point, viscosity, and complex modulus but decreased penetration. The tests revealed that using both kinds of fibers as modifiers for asphalt binders improves their high‐temperature performance by increasing the grade of the control binders (PG). This increase in asphalt binder stiffness is anticipated to enhance pavement rutting resistance. Consequently, these fibers can be used as additives for asphalt binders and asphalt mixtures to enhance their performance.

Enhancing the performance of asphalt binders is essential for ensuring the long-term durability and serviceability of asphalt mixtures, as it can help reduce the frequency of maintenance and repair work, ultimately leading to the development of more sustainable transportation infrastructure. To achieve this goal, this study investigates the effects of incorporating recycled polymer materials, including reclaimed polyvinyl chloride (PVC) and polystyrene (PS) derived from household waste, into hot mix asphalt. The experimental work involved subjecting the polymer-modified asphalt binders to a range of physical tests, such as softening point, penetration, ductility, indirect tensile strength, Marshall stability, and moisture susceptibility, and the results showed that the addition of recycled polymers, with an optimal content of 4%, led to lower penetration values and higher softening point temperatures, indicating improved resistance to temperature changes. Further analysis of the asphalt mixture performance revealed several beneficial outcomes, including a decrease in flow, a boost in the asphalt mixture's resistance to moisture-induced damage, and an improvement in Marshall stability and indirect tensile strength, with the inclusion of 4% recycled polymers yielding increases in Marshall stability of 43.7% and 37.4% for PVC and PS-modified mixes, respectively, and increments in indirect tensile strength of 32.2% and 29.7% for the same mixes. The study concludes that the use of recycled polymers can effectively enhance the performance and durability of asphalt mixtures, contributing to the development of more sustainable asphalt pavement construction practices by utilizing locally available or reused materials, which could lead to the increased knowledge and application of stronger and more weather-resistant asphalt mixes, ultimately promoting the advancement of sustainable transportation infrastructure.

This study investigates the effects of nano-silica, nano-chitosan, and nano-clay as asphalt binder modifiers, focusing on their physical and rheological properties. The nanomaterials were incorporated at concentrations of 2.5%, 5.0%, 7.5%, and 10% by weight. This research was driven by the growing adoption of nanomaterials, many of which are known for their toxicity and environmental impact. The results demonstrated a significant improvement in both physical and rheological properties, particularly in rutting resistance. Nano-silica demonstrated the greatest enhancement, leading to a reduction in permeability values, an increase in softening point, viscosity, and overall resistance to permanent deformation. Nano-chitosan exhibited a similar trend but with slightly lower performance values than nano-silica. Nano-clay provided the least improvement, though it still contributed to increased asphalt binder stiffness and reduced temperature sensitivity. Overall, the findings confirm that nano-silica, nano-chitosan, and nano-clay can improve asphalt binder properties, extending pavement lifespan and performance under increasing traffic demands. Further studies are recommended to explore the long-term aging resistance, fatigue behavior, and field applications of these nanomaterial-modified asphalt binders.

This study examines the environmental performance of asphalt pavement mixtures that incorporate recycled materials in Iraq, using Life Cycle Assessment (LCA) methods. Three pavement scenarios were evaluated: a baseline mix with 0% recycled content (S1), and two alternatives with 30% Recycled Asphalt Material (RAP) (S2) and 30% RAP plus 10% Crumb Rubber (CR) (S3) recycled content. The analysis used two well-known LCA tools, OpenLCA and SimaPro, to evaluate key impact categories: Global Warming Potential (GWP), Fossil Resource Scarcity, Human Toxicity Potential, Freshwater Eutrophication, and Acidification Potential. The results show that increasing the recycled content significantly reduces the environmental impacts across all categories. Scenario S3 had the lowest GWP, human toxicity, and acidification levels, demonstrating that recycled materials can reduce the carbon emissions. Adding CR resulted in reduced material demand, enhanced pavement durability, and lowered future maintenance and environmental impacts. Both OpenLCA and SimaPro showed similar trends, with OpenLCA proposed for future use because of its greater accessibility and cost-effectiveness. Overall, this research highlights the importance of using recycled materials in road construction to support sustainable development, especially in developing regions. It also stresses the need for region-specific Life Cycle Inventory (LCI) data to improve the model accuracy and guide environmentally responsible decisions in pavement engineering.

Incorporating crumbed rubber into asphalt binder or asphalt concrete mixes has become increasingly common in recent years. Researchers have looked into how well this additive can improve both the modified bitumen and the modified asphalt mix. With the growing usage of rubber crumb modifiers in asphalt mixtures, the significance of certain asphalt qualities has been recognized. This has opened up more opportunities for a thorough examination of their rheological and physical properties. The asphalt-rubber binder's performance was often impacted by the amount of crumb rubber and the blending circumstances. In this study, a new method, the Steam Aging Technique (SAT), was utilized to study the attributes of the rubber-enhanced bitumen, which was aged throughout Bitumen’s service. The primary goal of this research was to investigate the influence of traditional aging methods compared to the steam aging method, and the possibility of using the latter as an alternative test to traditional methods. Overall, physical test results showed notable increases in softening point and rotational viscosity and a decrease in penetration value for vapor-aged bitumen contrasted to non-aged bitumen. This research used a dynamic shear rheometer (DSR) and a temperature sweep test (TS) method to study rutting under control strain mode. The effectiveness of the use of steam aging has been observed and the possibility of using it as an alternative to the conventional aging methods available was investigated. It was found that there was a great convergence in the results extracted from the steam aging device with an addition rate of 5, 10, and 15% and an aging time of 45 minutes with the results extracted from the rotary kiln device, except for the 20% addition rate, which gave a difference in values.