Enhancing Effect of Waste Engine Oil Bottom Incorporation on the Performance of CR+SBS Modified Bitumen: A Sustainable and Environmentally-Friendly Solution for Wastes

Waste engine oil bottom (WEOB) is a hazardous waste whose effect as an additive to CR+SBS modified asphalt is rarely studied. In this study, the CR+SBS asphalt binder was modified with WEOB in different concentrations (3, 6, and 9 wt%). The GC–MS and FTIR were performed to evaluate the chemical compositions of WEOB and WEOBCR+SBS asphalt. The results showed that the main constituents of WEOB were similar to the functional groups of asphalt, along with maleic anhydride (MAH). Pavement performance-related rheological tests such as RV, temperature sweep (TS), FS, MSCR, and BBR were carried out. Results show that WEOBCR+SBS-6 exhibited the best high- and low-temperature property, followed by CR+SBS-3 and CR+SBS-9. Fluorescence microscope (FM) test, bar thin layer chromatograph (BTLC) test, FTIR, and AFM tests were carried out to evaluate the micro-morphologies and modification mechanism. The analysis revealed increased trends in resin fraction as opposed to asphaltene fraction with the increase of WEOB content. FTIR analysis revealed that the amide groups in WEOBCR+SBS asphalt bonded to the free radicals of CR. Moreover, a modification mechanism was elaborated. WEOB strengthens the cross-linked structure of CR+SBS polymers, reacting with SBS to graft onto MAH-g-SBS, and the free radical of CR interacts with the amide group in WEOB to form a bond. In addition, the content of lightweight components and surface roughness of SBS specimens were in good correlation, which contributed to the rutting resistance and adhesion and self-healing performance.

Resistance to Ultraviolet Aging of Nano-SiO2 and Rubber Powder Compound Modified Asphalt

Ultraviolet (UV) aging degrades the life span of asphalt pavement, nanomaterials used as modifiers exhibit good shielding function on UV light, but generally degrade the low-temperature property of asphalt, a compound modification was found to be a solution. In this study, nano-SiO2 and rubber powder were blended together with base asphalt to prepare compound modified asphalt. Compound modified asphalt with different blending dosages were subjected to UV light via a self-made UV aging simulation chamber. Basic performance tests and rheological tests were conducted including the UV aging influence. An optimum compound ratio was finally recommended based on the goal to remove the adverse effect of nano-SiO2 on the thermal cracking. Results show that the anti-UV aging property of asphalt is improved obviously due to the blocking function of nano-SiO2 and carbon black in rubber powder, and the enhancing effect of nano-SiO2 is found to be the most significant.