Characterizing blending efficiency of plant produced asphalt paving mixtures containing high RAP

•A method of measuring the blending efficiency of plant-produced mixtures using FTIR.•One warm mix and two hot mixes were used to validate the proposed method.•RAP particles varied in oxidation, virgin binder can reduce this heterogeneity.•Warm mix with foaming technology showed higher blending efficiency than hot mix.

The incorporation of high percentage (>30%) recycled asphalt pavement (RAP) into asphalt mixtures has become more popular. Various methods have been proposed to determine how much of RAP binder can be effectively blended into virgin binder. However, few methods can be used to test the blending efficiency of plant-produced asphalt mixtures. This study proposed a method of measuring the blending efficiency of plant-produced mixtures using Fourier Transform Infrared Spectroscopy (FTIR). Three types of asphalt mixtures, including one warm mix, two hot mixes with or without rejuvenator, were used to validate the proposed method. Results indicate that RAP particles varied in oxidation, but mixing RAP binder with virgin binder could reduce this heterogeneity. Among the three mixtures, warm mix showed the highest blending efficiency, while adding rejuvenator had a limited effect on the blending efficiency. The proposed method was further verified using Gel Permeation Chromatography (GPC).