Influence mechanism of crumb rubber pretreatment and antioxidants on aging and cracking behavior of rubberized asphalt

The use of rubberized asphalt technology is continuously increasing because of its sustainability benefits. Incorporating crumb rubber (CR) into asphalt binders enhances their overall performance. However, segregation of CR from asphalt in storage tanks remains a significant challenge. In this study, the solution soaking pretreatment employed potassium permanganate (KMnO₄) and hydrogen peroxide (H₂O₂) solutions. Two antioxidants, lignin and butylated hydroxytoluene (BHT), were incorporated. Three aging methods were applied: pressure aging vessel (PAV) thermal-oxidative aging, ultraviolet (UV) aging, and roof aging for one year. Fourier-transform infrared spectroscopy (FTIR) and thin-layer chromatography with flame ionization detection (TLC-FID) were used to characterize chemical changes. The fatigue performance and stiffness properties of the rubberized asphalt were evaluated using linear amplitude sweep (LAS) and bending beam rheometer (BBR) tests, respectively. Pretreatment with KMnO₄ and H₂O₂ increased the susceptibility of rubberized asphalt to oxidation, altering its chemical composition and aging behavior. Incorporating antioxidants, especially BHT, significantly enhanced the fatigue life, flexibility, and relaxation properties of rubberized asphalt. • Pretreatment increases oxidation susceptibility, causing hardness and elasticity loss. • Antioxidants help reduce aging-related issues, improving fatigue and promoting relaxation. • Realistic aging tests reveal distinct chemical and mechanical changes in asphalt. • KMnO 4 with BHT yields the best fatigue life and reduced stiffness in rubber asphalt.