Tuning high- and low-temperature rheological properties of warm-mixing asphalt composites by functionalized waxes

Abstract

Traditional asphalt road construction utilizes hot-mixing asphalt mixtures. High temperatures not only accelerate the aging of asphalt, but also produce large amounts of toxic and greenhouse gases. To alleviate these problems, wax-based warm-mixing agents are applied, and asphalt pavement construction temperatures can be efficiently lowered, resulting in lower energy and gas emissions. To systematically evaluate the effects of composition and structure of warm-mixing agents on rheological properties of asphalt at high and low temperatures, a series of functionalized waxes (i.e., oxygen-containing groups, amide groups, and long-chain aliphatic hydrocarbons) were designed in this work, followed by a melt-mixing process with asphalt. The findings demonstrated that warm-mixing agents with long-chain aliphatic hydrocarbons could significantly improve asphalt composites’ rheological properties at high temperatures, such as good viscosity-reducing effect and superior rutting resistance or permanent deformation resistance; warm-mixing agents with oxygen groups were able to improve the asphalt composites’ resistance to low-temperature cracking; amide group-containing warm-mixing agents could improve the surface roughness of asphalt composites. This work provides a practical guide for the selection of functionalized warm-mixing agents for asphalt pavement under multiple environmental factors.