Evaluating the Degree of Blending and Properties of Recycled Asphalt Mixtures Containing Fine Reclaimed Asphalt Pavement Particles Designed Across Different Methods

Owing to certain inherent deficiencies in their properties, fine reclaimed asphalt pavement (RAP) particles have not yet been widely reused worldwide, resulting in significant environmental pollution and economic waste. Currently, a diverse array of design methods for asphalt mixes has been proposed. These methods can exert a varying influence on the degree of blending (DoB) and the performance of recycled hot-mix asphalt containing fine RAP particles, and some methods may be better suited for recycling fine RAP particles. However, the specific effects and differences among these various methods have yet to be fully revealed. Therefore, this research comprehensively explored these behaviors. Four distinct mix design formulations were investigated: the dense-graded Asphalt Concrete Group (Group AC), the Stone Mastic Asphalt Group (Group SMA), the High-modulus Asphalt Concrete Group (Group HMAC), and the rejuvenator-modified Asphalt Concrete Group (Group AC+Re). It can be found that the DoB and performance varied across different groups. The DoB spanned from 69% to 82%, with Group SMA showing the highest and Group HMAC exhibiting the lowest. The tensile strength ratio (TSR) of Group AC performed only 73.7%, failing to meet the specification threshold; nevertheless, this shortfall can be compensated by employing alternative methods or adding rejuvenator. Group HMAC exhibited the highest splitting-tensile strength and fracture energy. In addition, the incorporation of rejuvenator can enhance most performance of mixes. Some findings may provide a new perspective for the application of fine RAP particles.