Low temperature performance evaluation indexes of asphalt binder based on EBBR test

Focusing on the evaluation indexes of the low temperature performance of asphalt binders, based on rheological bending beam rheometer (BBR) and extended bending beam rheometer (EBBR) tests, the low temperature rheological properties of the extracted asphalt, aging base asphalt and modified asphalt on actual pavements were analyzed. The low temperature performance evaluations of the asphalts were carried out using the traditional stiffness modulus and modulus changing rate. The equivalent low temperature design temperature index and the temperature difference value index were proposed. Simulations in different curing environments were conducted, and the influencing factors of physical hardening of newly prepared and extracted asphalt at low temperature were studied using low temperature grade loss index. Different sources and types of asphalt test results were used to verify each other, the above indexes were compared and analyzed in terms of anti-interference ability, stability, evaluation accuracy, intuitiveness, and difficulty in obtaining indexes. The abilities of four indexes in distinguishing and evaluating the low temperature performance of asphalt were established. Research results show that the laboratory rheological analysis of the extracted asphalt can reflect the low temperature crack resistance level of the pavement structure. The modulus of the asphalt in the severely cracked section is significantly higher than those in the other sections, and the value difference can reach about 130 MPa. The newly prepared SBS modified asphalt and the extracted asphalt have a high consistency at low temperature loads, and the modulus deviation is lower than 15%. It can effectively establishes the relationship between laboratory research and actual pavement disease treatment needs. The stability of traditional index data is weak, and the confidence is only 64.7%-82.3%, which is difficult to satisfy the research needs. The applications of temperature difference value index and low temperature grade loss index is also restricted, which still needs more in-depth research.. © 2021, Editorial Department of Journal of Traffic and Transportation Engineering. All right reserved.