Performance Evaluation of Warm-Mix Asphalt Binders with an Emphasis on Rutting and Intermediate-Temperature Cracking Resistance

Warm-mix asphalt (WMA) technology is gaining popularity worldwide due to its benefits of considerable emissions reduction and energy savings when compared with hot-mix asphalt (HMA). Currently, there is a wide range of WMA products with considerable variability in the corresponding pavement performances. It has also been difficult to reach a unified conclusion regarding the effects of various WMA additives on asphalt binder properties. In this study, two categories of warm-mix additives, including six organic additives and three chemical additives, were evaluated in terms of their effects on asphalt binder properties, with a focus on rutting and intermediate-temperature cracking. It was found that the viscosity-reducing effect of organic additives was more significant in comparison to chemical additives. In addition, the binders modified with the organic additives obtained enhanced rutting resistance at high temperatures but compromised cracking resistance at intermediate temperatures, as shown by the increasing complex modulus (<i>G*</i>) and non-recoverable creep compliance (<i>J_nr</i>) and decreasing binder fracture energy (BFE). Meanwhile, the very limited effect of chemical additives on rutting resistance was observed while the cracking resistance was slightly improved. The findings will assist in the selection and application of WMA additives for the production of asphalt mixture.