Mechanism of low- and intermediate-temperature performance improvement of reclaimed oil-modified asphalt

To better understand oil modifiers' effects on the performance of asphalt binders at low and intermediate temperatures and the mechanisms of the modification, laboratory tests including mechanical property tests and microscopy tests are performed. It is found that oil modifiers can improve the performance of asphalt binders at low and intermediate temperatures significantly. By comparing the absorption peaks of oil modifiers, neat binder and oil-modified asphalt, it is found that the oil modification of asphalt is mainly by physical modification. In addition, a new partition method using gel permeation chromatography spectrum is recommended to investigate the modification mechanism of oil-modified asphalts. With this new method, it is found that the large molecular size (LMS) content correlates well with low-temperature performance; parameter B calculated from fatigue equation correlates well with the content of medium molecular size (MMS), and fatigue life also has a relatively good relationship with LMS. Overall, it is shown that oil modifiers improve the performance of binders at low and intermediate temperatures by decreasing the LMS and MMS of contents.