Effect of gradations on the final and long-term performance of asphalt emulsion cold recycled mixture

The influence of different gradations on the final and long-term performance of cold recycled mixture with asphalt emulsion (CRME) was investigated. The weight ratio of recycled asphalt pavement (RAP) to virgin aggregate and mineral powder remained 4:1 unchanged, three gradations were selected in a modified grading range which was determined based on the engineering practices of Hunan province and the Chinese specification for cold recycling (JTG F41-2008). The tested performance included mechanical property, moisture susceptibility, high-temperature stability, low-temperature cracking resistance and long-term performance. The long-term performance was simulated using a laboratory accelerated aging test. The results show that CRMEs with the selected three gradations have good above-mentioned performance, manifesting that the modified grading range for guiding the CRME engineering practices is feasible to some extent. As the aging time goes on, the indirect tensile strength (ITS) and freeze-thaw ITS ratio of all CRMEs firstly increase quickly and then increase slowly or even decrease, and the aging of asphalt in CRME becomes more and more serious. Compared with three gradations, the CRME with finer gradation has the better final and long-term performance. Moreover, after long term service, the effect of gradation on mechanical property of CRME becomes more significant.