The main objective of this research is to develop a sustainable and environment-friendly asphalt binder based on the reutilization of waste engine oil (WEO) alongside crumb rubber (CR), two major waste materials of the automobile industry. This composite modification eliminates the limitations and the negative effects of solo application of these waste modifiers, including the poor workability and pumpability of the CR-modified binder, as well as compromised rutting resistance of the biobinder modified with WEO. Besides investigating the high-temperature properties of the composite-modified binder with CR and WEO, for the first time, a new method is presented to analyze the influence of the preparation parameters on the performance of the binder and optimize the whole production process. For this purpose, the design of experiment was conducted with the aid of the central composite design (CCD) method, and the rheological properties of the binders were evaluated by rotational viscosity (RV), dynamic shear rheometer (DSR), and multiple stress creep recovery (MSCR) tests. Based on the results of rotational viscosity at 135°C and the unaged and RTFO-aged rutting factor values at 58°C, regression models were established and analysis of variance was carried out on the preparation parameters. Overall, test results indicated that the addition of 5%–10% blending content of WEO in the composite-modified binder could achieve a satisfactory rutting resistance while improving its workability and pumpability. On the other hand, although the content of WEO had the most significant influence on the rheological properties of the binder samples, other parameters including preparation temperature and time also had influence to some extent. Additionally, optimum values of the preparation parameters were determined, and the production process was optimized.

Using waste plastics in pavement construction has been attracting significant attention because of its ability to increase the sustainability of the road infrastructure, economic benefits, and superior performance with regard to resistance against rutting. However, poor compatibility, mainly because of differences between the properties of plastics and asphalt with regard to density, molecular weight, polarity, and solubility, has been one of the major drawbacks that has been limiting their successful application. As a result, this study aims to use a wax-based product, which is a by-product of the pyrolysis of waste polyethylene, to enhance the compatibility between asphalt and two main types of polyolefins: polyethylene and polypropylene. The main objective was to use pyrolysis wax to enhance the compatibility between asphalt and plastics, as well as eliminating two of the primary downsides of plastic-modified asphalt: poor resistance to cold weather and fatigue-related cracks. To achieve this, after the incorporation of pyrolysis wax to plastic-modified asphalt during the wet modification process, the rheological performance of the asphalt containing plastics was evaluated by conducting different laboratory testing. The results indicate that a proper ratio between pyrolysis wax additive and plastic asphalt binder containing 2% polyolefins and 1.5% pyrolysis wax overall can demonstrate a superior performance with regard to the different aspects of performance, including resistance against rutting, thermal cracking, and fatigue, without sacrificing any other aspects of the performance when compared with base PG 58-28 binder and plastic-modified binder.

This paper presents a comprehensive review of the environmentally friendly management and reutilization of electronic waste (e-waste) plastics in flexible pavement construction. The discussion begins with an overview of e-waste management challenges and outlines key recycling approaches for converting plastic waste into asphalt-compatible materials. This review then discusses the types of e-waste plastics used for asphalt modification, their incorporation methods, and compatibility challenges. Physical and chemical treatment techniques, including the use of free radical initiators, are then explored for improving dispersion and performance. Additionally, in situations where advanced pretreatment methods are not applicable due to cost, safety, or technical constraints, the application of alternative approaches, such as the use of low-cost complementary additives, is discussed as a practical solution to enhance compatibility and performance. Finally, the influence of e-waste plastics on the conventional and rheological properties of asphalt binders, as well as the performance of asphalt mixtures, is also evaluated. Findings indicate that e-waste plastics, when combined with appropriate pretreatment methods and complementary additives, can enhance workability, cold-weather cracking resistance, high-temperature anti-rutting performance, and resistance against moisture-induced damage while also offering environmental and economic benefits. This review highlights the potential of e-waste plastics as sustainable asphalt modifiers and provides insights across the full utilization pathway, from recovery to in-field performance.

As the global demand for electronic equipment continues to grow, many devices are being replaced more frequently, resulting in a rapid rise in electronic waste (e-waste), now the fastest growing waste stream worldwide. Motivated by this, the objective of this study is to present an environmentally friendly method to recycle acrylonitrile–butadiene–styrene (ABS), one of the most common e-waste plastics, by using it for asphalt production. In contrast to earlier methods of plastic-modified asphalt production involving complex pretreatments or complimentary additives unsuitable for plant-scale use, this study aims to demonstrate a practical, low-cost solution through the use of carbon black. This approach included physically pretreating ABS plastics for size reduction and incorporating waste tire-derived carbon black to promote effective dispersion in asphalt during wet modification. The rheological properties of the e-waste-modified asphalt were subsequently assessed. The test results indicated that recycling ABS plastics with a blending content of 5% alongside 5% carbon black can enhance cold-weather cracking resistance and high-temperature anti-rutting performance of asphalt. The enhancement can be attributed to the proper preparation procedures of ABS plastics and the addition of carbon black, which can further improve the performance by promoting the proper dispersion of plastic particles in asphalt. The outcome of this study indicates that recycling e-waste plastics through asphalt production can lead to more green and sustainable asphalt construction, reduce total construction costs, and most importantly enhance performance.