ABSTRACT
The recycled asphalt pavement material RAP is affected by the aging asphalt wrapped on the aggregate surface during the hot mixing process, and cannot be completely dispersed during the mixing process, resulting in the difference between the actual gradation and the design gradation, which affects the accuracy of mineral aggregate gradation. To solve this problem, this paper studies the influence of the direct screening method and combustion furnace method on the gradation difference of RAP with different particle sizes. And through the orthogonal test, the influence law of different combinations of dispersion coefficients on the voids of recycled asphalt mixture is studied. On this basis, the best dispersion coefficient combination is used to modify RAP gradation to prepare the asphalt mixture, then the road performance of the asphalt mixture is measured and evaluated. The research results show that the gradation results obtained by the direct screening method and combustion furnace method are quite different, and RAP with different particle sizes will produce gradation variation in different situations. The orthogonal test results show that the Type III square of RAP-2 (0 ~ 5mm) is smaller, which is 1.327, indicating that the gradation composition of RAP in this particle size range is a more important factor affecting the gradation design of the mixture. The best-modified dispersion coefficients of RAP-1 (5 ~ 10mm) and RAP-2 are 0.4 and 0.8 respectively. The porosity, Marshall stability, dynamic stability, and low-temperature bending strain of recycled asphalt mixture prepared by the combination of these dispersion coefficients are 3.8%, 14.81kN, 5650 times/mm, and 2911.8 με respectively.
