A Nano-Scale Approach to Study the Healing Phenomenon in Warm Mix Asphalt

摘要

During the past decade, new technologies such as warm mix asphalt (WMA) technology have been used to help in reducing the carbon footprint of asphalt pavements. However, there are still unanswered questions and concerns regarding the long-term performance of asphalt material produced using these technologies. One of these questions is the influence of using these technologies on the healing behavior of asphalt binders, which might have a significant impact on their performance. In this paper, a nano-scale approach that uses atomic force microscopy (AFM) was developed and employed to evaluate the effect of different WMA technologies on the healing characteristics of commonly used asphalt binders, namely, PG 64-22, and PG 70-22M. The considered WMA technologies included: Advera®, Evotherm® Ml, Sasobit®, and foamed WMA. The results of this paper indicated that Advera®, Evotherm® Ml, and foamed WMA technologies improved the micro-crack closure rate in the considered asphalt binders. Furthermore, only the Sasobit significantly decreased the cohesive bonding energy in the asphalt binders, which may suggest that it may adversely affect their intrinsic healing. The other WMA technologies improved the hydroxyl cohesive bonding energy with an asphalt binder but did not significantly influence the carboxyl cohesive bonding energy.