The global plastic crisis has generated significant interest in repurposing waste plastics as asphalt modifiers, presenting both environmental and engineering advantages. This study offers a comprehensive review of the applications of waste plastics in asphalt, focusing on their types, modification mechanisms, incorporation techniques, and environmental impacts, alongside proposed mitigation strategies. Commonly utilized plastics include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET), each affecting asphalt performance differently—enhancing high-temperature stability and fatigue resistance while exhibiting varying levels of compatibility and environmental risks. The incorporation techniques, namely wet and dry processes, differ in terms of efficiency, cost, and environmental footprint: the wet process enhances durability but requires more energy, whereas the dry process is more cost-effective but may lead to uneven dispersion. Environmental concerns associated with these practices include toxic emissions (such as polycyclic aromatic hydrocarbons and volatile organic compounds) during production, microplastic generation through abrasion and weathering, and ecological contamination of soil and water. Mitigation strategies encompass optimizing plastic selection, improving pre-treatment and compatibilization methods, controlling high-temperature processing, and monitoring the spread of microplastics. This review highlights the need for balanced adoption of waste plastic-modified asphalt, emphasizing sustainable practices to maximize benefits while minimizing risks.

Epoxy asphalt is a superior polymer-modified asphalt material; however, significant differences in physicochemical properties, such as solubility parameters and dielectric constants, between epoxy resin and asphalt have led to compatibility issues that hinder its development. This study employed molecular dynamics simulations to investigate the effect of maleic anhydride-grafted styrene-butadiene-styrene (MAH-g-SBS) on the compatibility of epoxy asphalt. By analyzing parameters such as cohesive energy density, solubility parameters, energy distribution, interaction energy, radial distribution function, free volume fraction, and mean square displacement, the molecular mechanism underlying the enhanced compatibility was elucidated. The results indicate that the amphiphilic molecular structure of MAH-g-SBS significantly improves the thermodynamic compatibility between asphalt and epoxy resin, enhances interfacial affinity and stability, reduces the system’s total interaction and nonbonded energies, facilitates the dispersion and permeation of epoxy molecules into asphalt, and increases molecular mobility, thereby comprehensively enhancing the compatibility of the epoxy asphalt blend. Segregation tests and fluorescence microscopy further verified the simulation results, demonstrating that MAH-g-SBS improves the storage stability and phase uniformity of the epoxy asphalt system.

Water-based drilling cuttings (WBDCs) are a large-volume solid waste generated during oil and gas drilling. Their weak cementation and loose particle structure limit their direct engineering utilization. In this study, a multi-source solid-waste binder mainly composed of ground granulated blast furnace slag (GGBS) and fly ash (FA) was used to stabilize WBDCs. Portland cement was used as an auxiliary binder, and sodium silicate was used as the alkaline activator. The effects of sodium silicate modulus, sodium silicate dosage, cement dosage, and GGBS-to-FA mass ratio on strength development were investigated. XRD, FTIR, TG, MIP, and SEM-EDS were further employed to clarify the stabilization mechanism. The results showed that binder composition strongly affected the strength level and strength development rate of stabilized WBDCs. At a total binder dosage of 15%, the mixture with a sodium silicate modulus of 1.4, a sodium silicate dosage of 4%, a cement dosage of 10%, and a GGBS-to-FA mass ratio of 6:1 exhibited the best mechanical performance. Its unconfined compressive strengths reached 6.87, 9.74, and 10.17 MPa at 7, 14, and 28 d, respectively. Microstructural analyses indicated that the strength development of stabilized WBDCs was mainly associated with the formation and continued development of poorly crystalline C-S-H/C-(A)-S-H-type gels and a small amount of AFt. From 7 to 28 d, the porosity and total pore volume decreased by 9.5% and 11.0%, respectively, while the average pore diameter decreased by 31.2%. This study provides a basis for the resource utilization of WBDCs and the design of low-cement binders containing multiple industrial solid wastes.