Study on the Aging Behavior of Asphalt Binder Exposed to Different Environmental Factors

Abstract

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.