Evaluation of chemical and rheological properties of warm mix asphalt binders considering binder source, additive type, and aging

Warm mix asphalt (WMA) technologies have long been used without compromising the performance of asphalt concrete. However, no research has yet investigated the chemo-mechanisms of WMA-modified binders considering the effect of binder source, additive type, and aging. Thus, in this study, the changes in chemical, physical, and rheological properties of four WMA-modified binders produced with two different WMA additives using two different binder sources were comprehensively analyzed experimentally and statistically, compared to the base binders. Initially, the chemical properties of original, short- and long-term aged binders are determined according to polar fractions using the weight-based SARA method and molecular constituents using FTIR spectroscopy to gain insight into the chemo-mechanisms between the additives and binders. Then, these relative changes in chemical properties through aging are related to physical and rheological properties regarding binder source and WMA additives. Consequently, the results show that the chemical properties of the WMA-modified binders strongly depend on the binder source and additive type, which is reasoned based on chemo-mechanisms. Moreover, it is revealed that the relation between asphaltene fraction and rheological properties of WMA-modified binders varies depending on the binder source, unlike base binders. Gastel indices can well represent the aging rate of WMA-modified binders.