Evaluation of Complex Shear Modulus of Recycled Asphalt Mortars Based on Euclidean Distance Method in the Mixing Process

The fine aggregate of reclaimed asphalt pavement (RAP) contains a large amount of aged asphalt, but the recovery of aged asphalt performance is unstable during the conventional regeneration processes. In this study, the complex shear modulus (G*) recovery of recycled asphalt mortar was quantified by the Euclidean distance method to determine the process of preparing recycled asphalt mortar from oil-rich RAP fine aggregate. Firstly, recycled asphalt mortars were prepared given different process parameters, such as mixing temperature, mixing rate and mixing time. Then, the dynamic shear rheological test was conducted on the recycled asphalt mortar, and its performance recovery rate was evaluated by the Euclidean distance method. According to the results, all the three process parameters showed a positive correlation with the performance recovery of recycled asphalt mortar. The effect of mixing temperature on the performance recovery of recycled asphalt mortar was more significant compared to mixing rate. The recycled asphalt mortar showed a significant performance recovery when the mixing time was in no excess of 15 min. In addition, the G* of recycled asphalt mortar was quantitatively evaluated and the optimal process parameters were determined. The further preparation of recycled asphalt mortar into mixtures has significantly improved low-temperature crack resistance and water stability performance based on the optimal regeneration process, thereby compensating for the shortcomings of recycled asphalt mixture. This study provides reference both in theory and practice for investigation into the performance recovery of recycled asphalt mortar.