Typical climatic environments such as UV radiation, high temperature and strong wind in cold and arid regions have a significant effect on asphalt aging. The intent of this work is to reveal the evolution law of natural aging of SBS-modified asphalt under the complex adverse climate environment in cold and arid regions. Furthermore, the contribution rate of various environmental factors of natural aging of asphalt in cold and arid regions was analyzed. Based on rheological parameters, this paper characterized the influence of natural aging on the viscoelastic properties, rutting resistance at a high temperature, fatigue resistance and cracking resistance at a low temperature of SBS-modified asphalt. The evolution law of natural aging performance of SBS-modified asphalt was revealed. A quantitative evaluation index (CIi) of natural aging contribution rate of asphalt was put forward and the contribution rate of various environmental factors to asphalt natural aging was analyzed. The results showed that the effects of simulated aging and natural aging on asphalt properties were similar. After aging, the viscoelastic properties of asphalt were deteriorated, and the risk of fatigue cracking and low temperature cracking was increased. It also enhanced the deformation resistance of asphalt and increased the rutting resistance at high temperature. The aging contribution index CIi obtained based on rheological parameters such as complex modulus and rutting factor could directly reflect the influence of different natural factors on the performance of asphalt during aging. Among them, the effect of thermal oxygen was more obvious on the natural aging of SBS-modified asphalt.

Accelerated aging methods commonly used in laboratories struggle to replicate the outdoor aging process of asphalt binder. The aim of this study is to elucidate the impact of different environmental factors on the aging of asphalt binder and recreate the exposure process of asphalt binder. To achieve the study’s objectives, the asphalt binder was subjected to various environmental conditions through different aging modes. Three exposure modes (all environmental factors, the effects of light, temperature, oxygen, the effects of temperature, oxygen, and others) were established to assess the impact of various environmental factors on asphalt binder aging behavior. This mode was labeled O+UV-aging, earning it the name O-aging. The aging behaviors were assessed across multiple dimensions, considering apparent morphology, rheological properties, and chemical composition. The study’s findings highlight that factors such as ultraviolet radiation are primarily responsible for the formation of micro-cracks and increased surface roughness in aged asphalt binder. Ultraviolet radiation significantly affected the aging of asphalt binder during outdoor exposure. SBS modifiers increased the risk of fatigue cracking in the virgin asphalt binder but enhanced its aging resistance. After All-aging, the G-R parameter increase of virgin asphalt binder was 2.6 times that of SBS-modified asphalt binder. Throughout the exposure process, the broken molecular chains and the original molecular chains in the asphalt binder underwent polymerization reactions, resulting in longer carbon chains and cycloalkane aromatization. It was discovered that exposure showed less effect on the characteristic functional groups of SBS-modified binder than on virgin binder. After All-aging, the carbonyl index of SBS-modified asphalt binder was 56.4% higher than that of virgin asphalt binder.