The widespread production and consumption of plastics is a pressing global issue that requires multifaceted approaches and solutions. In terms of recycling, one of the ways to repurpose waste plastics in the construction industry would be to utilize them for asphalt pavement-related applications. Although this approach can potentially provide a value-added recycling outlet for plastics, several challenges need to be resolved to maximize its usage to the highest possible extent. Based on this, the present review article provides a comprehensive background on the different pertinent aspects associated with the use of waste plastics in asphalt mixtures. Besides examining the mechanical performance of asphalt mixtures containing waste plastic, the associated environmental concerns and life cycle assessment related attributes are also thoroughly deliberated. In addition, the successful demonstration of this technology through field trials in several countries is also discussed. Some of the main challenges related to the use of plastics in asphalt mixtures include the variability of plastic properties and composition, which can influence its mechanical performance and associated environmental impact. In general, the incorporation of waste plastics using certain tailored approaches can adequately meet and even enhance the typical performance parameters of asphalt mixtures. However, the effect of plastics modified asphalt mixtures on fuming and microplastics release remains unclear and needs further research. Nevertheless, the increasing number of field trials and widespread interest from transportation agencies around the world indicate the likelihood for the adoption of this technique as a sustainable practice in the pavement industry.

Improvement in rheological performance of asphalt binder with the addition of crumb rubber (CR) depends on the interaction between CR and the asphalt binder matrix. Overall, the change in any rheological property of asphalt binder with the addition of CR can be attributed to two factors: the chemical interaction between CR and the asphalt binder matrix, termed the interaction effect (IE); and the filler nature of CR particles, termed the particle effect (PE). The present research was undertaken to quantify the relative contribution of IE and PE to various parameters responsible for changes in mixing and compaction temperature, high-temperature properties, and intermediate-temperature properties through various rheological approaches. Accordingly, viscosity, G*=Sinδ, multiple stress creep recovery (MSCR), and linear amplitude sweep (LAS) were tested using base binder modified with two CR particle sizes (ASTM# 30-40 and ASTM# 60-80) and keeping the amount of CR constant at 15% by base binder weight. In order to understand the contribution of IE and PE on different rheological parameters, three sets of samples for each CR size were prepared: (1) base binder, (2) undrained CR-modified binder, and (3) drained CR-modified binder. The effect of CR particle filler nature (through PE) was found to be significantly greater than the effect of chemical interaction (through IE) on viscosity, G*=Sind, recovery, and fatigue life. On the other hand, along with PE, the chemical interaction between CR and asphalt binder matrix (IE) was found to play a significant role in improving nonrecoverable creep compliance response. Additionally, based on comparative analysis of IE and PE in various performance-related parameters, the filler effect produced with the addition of 30-40CR particles was found to be more than the filler effect produced with the addition of 60-80CR particles. This indicates that increased CR particle size may cause changes in the filler nature of the CR-asphalt binder composite. Additionally, hightemperature storage stability was evaluated. Base binder with 60-80CR particles exhibited better stability than base binder with 30-40CR particles.