Influence of characteristics of recycling agent on the early and long-term performance of regenerated SBS modified bitumen

Abstract

The increasing reclaimed asphalt pavement mixture causes environmental pollution and a waste of resource, which could be resolved by the asphalt recycling technology. In this paper, corn oil, waste engine oil, vacuum stream oil and cashew shell oil are used for rejuvenating aged SBS modified asphalt (ASMA), and the effect of composition, structure and thermal-oxidative stability of recycling agents on the early and long-term performance of rejuvenated binder are thoroughly investigated. The results indicate cashew shell oil with nut phenol derivatives has the best rejuvenating effect on ASMA, corn oil containing aliphatic hydrocarbons is more conducive to improving the low temperature performance of rejuvenated ASMA, and vacuum stream oil containing nonpolar alkane compound shows the worst regeneration effect. Meanwhile, simultaneous thermal analysis reveals nonpolar aliphatic hydrocarbons vacuum stream oil has the poorest thermal stability for its lowest initial decomposition temperature 146 °C, while initial decomposition temperature of cashew shell oil and corn oil are all over 200 °C. The changes of physical and rheological properties of cashew shell oil rejuvenated ASMA after aging are much smaller than that of others, which indicates cashew shell oil with excellent thermal-oxidative stability is more conductive to inhibiting the transition from viscosity to elasticity of rejuvenated binder in the aging process. While vacuum stream oil rejuvenated ASMA shows the most serious aging degree, suggesting the poor thermal-oxidative stability of recycling agents has adverse effects on the anti-aging properties of rejuvenated binder. Infrared spectrum analysis indicates the aging index growth rate of cashew shell oil rejuvenated ASMA is the smallest, also demonstrating the best aging resistance of cashew shell oil rejuvenated ASMA. The correlation coefficients between sulfoxide index and physical-rheological properties are almost all higher than 0.90, while that between sulfoxide index and physical-rheological properties are lower than 0.71, therefore sulfoxide index can be a better indicator for estimating the physical-rheological properties of rejuvenated SBS modified bitumen in the service.