Effect of Crumb Rubber Dissolution on Low Temperature Performance and Aging of Asphalt-Rubber Binder

摘要

Asphalt binder plays a critical role in defining the low temperature performance of the asphalt pavement and therefore, enhancing its low temperature mechanical behavior through modification always has been of a great interest. Crumb rubber modification of asphalt is one of the common practices in the industry. However, the effect of Crumb Rubber Modifier (CRM) on low temperature performance of the binder is not well understood. CRM swells through absorbing the aromatics and light molecular components of asphalt at low interaction temperatures (i.e. 160°C) and dissolves at higher interaction temperatures (i.e. 190°C, 220°C). Each of these activities affects the performance of the CRM asphalt differently. In this research, the activities of CRM in asphalt controlled accurately through regulating the interaction conditions and the effect of each of those activities on low temperature behavior of asphalt was studied using Bending Beam Rheometer (BBR) and Modulated Differential Scanning Calorimetry (MDSC). BBR was used to measure the mechanical behavior of CRM asphalt and its liquid phase at low temperatures as a function of CRM dissolution, and MDSC was utilized to investigate changes in glass transition of the liquid phase of the modified binder. The results indicate that the stiffness and m-value of the modified binder are developed in two different manners and the factors that affect these two parameters are different. The results also show that through certain interaction conditions, it is possible to optimize the low temperature performance of the CRM asphalt.