Estimation of Low-Temperature Performance Grading of Modified Asphalt Binders Using the Critical Stress Intensity Factor

Abstract

Cracking in pavements due to low temperature is the predominant distress in cold climate areas. The bending beam rheometer (BBR) test is typically utilized to determine the low-temperature performance of the asphalt binders. This procedure takes around 24 h because two preliminary tests including the pressure aging vessel test and rolling thin film oven test must be performed. In the current study, as a new methodology, the capability of the single-edge notched bending (SENB) test, which is completed in a shorter period of time, was evaluated to estimate the low-temperature performance grading of the asphalt binders. For this, the fracture toughness in Mode I (KIC) and fracture energy of nine types of asphalt binders were measured at temperatures of 0°C to −40°C. Meanwhile, the m-value (the rate of change of creep stiffness at 60 s) and creep stiffness of the asphalt binders were determined. The test results indicated that asphalt binder type and temperature influence the fracture energy and KIC of the asphalt binders. Furthermore, analysis of the tests results showed that the KIC increased with decreasing temperature, and the temperature corresponding to KIC less than 30 kPa·m0.5 may be a good indicator for estimating the low-temperature performance of the asphalt binders. The bending beam rheometer test is typically utilized to determine the low-temperature performance of the asphalt binders. This test takes around 24 h because two preliminary tests including the pressure aging vessel test and rolling thin film oven test must be performed; meanwhile these tests need special equipment that may be unavailable in the laboratories or projects. According to the findings of this research study, to determine the approximate low-temperature performance of the asphalt binder, instead of performing the bending beam rheometer test, which is time-consuming and needs special equipment, the single-edge notched bending test that is completed in a shorter period of time can be carried out at different temperatures. The minimum temperature at which the value of the fracture toughness in Mode I (KIC) is equal to or less than 30 kPa·m0.5 may be considered as an estimation of the low-temperature performance of the asphalt binder.