A laboratory investigation into the effect of waste non-tire rubber particles on the performance properties of terminal blend rubberized asphalt binders

Non-tire rubber products (e.g. hoses, weather strips, vibration insulators, and miscellaneous parts) are progressively increasing as scrapped and repaired vehicles rise, and are abundantly discarded due to various reasons, such as high-cost recycling, complex rubber components, and poor mechanical properties. The non-tire rubber products have similar chemical components as scrap tires that have been widely applied in the field of road engineering, so it is anticipated that waste non-tire rubber products can be pretreated and used in road engineering as scrap tires. Hence, the purpose of this study was to gain a comprehensive understanding of asphalt binders modified with waste non-tire rubber with or without a microwave and/or waste engineering oil (WEO) treatment by using the terminal blend (TB) process as crumb rubber. A variety of laboratory tests were conducted, including scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric coupled with FTIR (TG-FTIR), storage stability, high-temperature performance, fatigue, and other basic rheological properties. It was found that microwave irradiation and WEO treatment can accelerate the pyrolysis and decomposition of waste non-tire rubber particles while there were no obvious differences between the pyrolysis gaseous products of waste non-tire rubber particles with or without the microwave or/and WEO treatment. Additionally, the microwave or/and WEO treatment enhanced the thermal stability and fatigue resistance of TB rubberized asphalt, especially for that with 100% WEO and 40 mesh of non-tire rubber particles. The microwave or/and WEO treatment reduced the viscosities and high-temperature properties of TB rubberized asphalt, especially for TB rubberized asphalt with fine rubber particles. In general, it is feasible to use waste non tire rubber particles to produce TB asphalt binders and offer a cleaner way of using waste non-tire rubber products. The method of microwave and WEO treatment can be used to prepare TB asphalt with high content of non-tire rubber particles in the future.