Effect of modifier on Low-Temperature reversible aging behavior of asphalt binder and its morphology analysis. (10th October 2022) - Ren, Mingkai
Highlights: Rubber powder can alleviate the effect of reversible hardening on asphalt binders. The addition of modifiers can reduce the reversible hardening degree of the asphalt binder. Cone penetration test can be used to characterize the reversible hardening degree of the asphalt binder. With the extension of conditioning time, the average area of asphalt binder "bee" structure increases gradually. Abstract: Reversible aging of asphalt binders is one of the reasons for the premature failure of asphalt pavements. To better understand the effect of modifier types on the reversible aging in asphalt binder, styrene–butadienestyrene (SBS), styrene-butadiene rubber (SBR), crumb rubber (CR), and Nano-CaCO3 were selected to prepare modified asphalt binder. Firstly, an extended bending beam rheometer (Ex-BBR) test and a cone penetration test (CPT) were carried out on base asphalt (BA) and modified asphalt binders under different conditions. Secondly, the reversible aging behavior of asphalt binders was characterized using a logistic regression model. Furthermore, the mechanisms of asphalt reversible aging were analyzed by atomic force microscopy (AFM) and molecular dynamics (MD) simulation. The results show that the addition of modifiers affects the reversible aging behavior of asphalt binders. Compared with SBS, SBR, and nano-CaCO3, CR can improve the mobility of asphalt molecules and mitigate the aggregation of asphalt molecules, thereby alleviating the impact of reversible aging on asphalt binder performance. After 72 h low-temperature conditioning, CR modified asphalt binder has the smallest grade loss of 1.7 °C. The low-temperature conditioning time can greatly affect the microstructure of the asphalt binder. With the increase of low-temperature conditioning time, the average area of the asphalt binder's "bee" structures increases linearly. Furthermore, the reversible aging behavior of asphalt binders can be better understood using MD simulation.