Published Online: 25 March 2013
Page Count: 8
Assistant Professor, Dept. of Civil and Environmental Engineering, Washington State Univ., Pullman, WA
Student, Dept. of Civil and Environmental Engineering, Washington State Univ., Pullman, WA
(Received 27 January 2012; accepted 6 December 2012)
Thermal cracking is one of the primary distresses in asphalt pavements. Asphalt binder, an important component of asphaltic concrete, plays a significant role in the thermal cracking performance of asphalt pavement and should be characterized accurately for proper binder selection. The current Superpave binder specifications for low-temperature cracking, based on creep stiffness and m-values, are not applicable to modified binders. Fracture-based tests are most promising for the prediction of low-temperature cracking of binders, especially modified binders. This study develops a new performance indicator for low-temperature cracking using properties from monotonic testing at a semi-low temperature, 5°C, based on the dynamic shear rheometer (DSR). It is found that the complex shear modulus of binders does not correlate with field thermal cracking performance. Fracture energy shows a moderate correlation with field thermal cracking performance. The correlation is improved when the shear rate is increased. However, failure strain at 5°C correlates very well with field thermal cracking. In addition, failure strain is not sensitive to the shear rate at 5°C. This new test could significantly reduce the costs associated with the purchase of various types of equipment, such as that needed to conduct bending beam rheometer (BBR) or direct tension tests, and could also reduce the amount of testing time. Further study is needed to validate the findings in this study.
Paper ID: JTE20120001