Low temperature and fatigue characteristics of treated crumb rubber modified asphalt after a long term aging procedure

Abstract

Crumb rubber modified asphalt has been widely applied in highway construction fields for its environmentally friendly characteristics and also to satisfy the demand of asphalt pavement at different application conditions. Rubberized binders achieve the recycling of scrap tires, reduce the consumption of raw materials and act as an economically beneficial construction material to asphalt pavement. However, long term aging adversely affects the low temperature performance characteristics and fatigue resistances of rubberized binders. In order to improve the aging resistance of asphalt rubberized binder, a surface treatment was applied on three crumb rubbers. In addition, two binder sources were used to produce the treated crumb rubber modified asphalts to explore their aged performances. In this research, stiffness values and m-values of pressure-aged vessel (PAV) aged rubberized asphalts were obtained from bending beam rheometer (BBR) test at −6 °C, −12 °C and −18 °C to determine their minimum low temperatures and to evaluate their cracking resistances. Meanwhile, fatigue resistances of all binders were evaluated by the linear amplitude sweep (LAS) test and the fatigue factor referred as G* sin δ at the test temperature of 25°Cthrough the dynamic shear rheometer (DSR) test. Additionally, Thermal Gravity (TG) and Differential Scanning Calorimeter (DSC) test were conducted on all rubbers to explore their thermal stabilities and determine their glass transition temperatures. The results showed that rubbers had good thermal stability at the mixing temperature and the treatment on rubbers promoted the low temperature performance for most rubbers. In addition, positive influences on low temperature properties were observed on the binders produced with medium size rubber in this study. Meanwhile, as expected, binders produced with softer virgin asphalt generally had better cracking resistances regardless of rubber type.